THE USE OF SUBSTITUTED NITRO AND CYANOGUANIDINES FOR INCREASING CROP YIELD

Abstract: Novel substituted phenyl and benzyl nitro-guanidine and phenyl and benzyl cyanoguanidine compounds. Methods for increasing crop yield, inhibiting lodging of graminaceous crops, and inducing cytokinin-like responses in crop plants with said novel guanidine compounds and derivatives thereof, as well as methods for inhibiting deterioration and/or extending the shelf life of harvested fruit, vegetables, and ornamentals are disclosed.

Description: SUBSTITUTED NITRO AND CYANOGUANIDINES AND THEIR USE FOR INCREASING CROP YIELDS The present invention relates to certain novel nitro and cyanoguanidine compounds. Additionally, the invention relates to the use of certain guanidines useful in a variety of plant-growth regulating activities. The guanidine compounds of the present invention include novel substituted phenyl and benzyl nitroguanidines and novel phenyl and benzyl cyanoguanidines. Although nitro and cyanoguanidines are disclosed in the art, the presently-described compounds are novel. In addition to the novel compounds of the present invention, it has been unexpectedly discovered that certain guanidines possess heretofore undisclosed plant growth regulating activities. These plant growth regulating actions include increases of certain crop yields, as well as inhibition in deterioration of harvested crops and ornamentals. It is an object of the present invention, therefore, to provide the novel nitro and cyanoguanidines described more fully below. It is a further object of this invention to disclose methods of using certain guanidines as plant growth regulants. Furthermore, these guanidines exhibit growth regulating activities in such fashion as increasing crop yields and inhibiting deterioration of harvested crops and ornamentals. These and other objects of the present invention will become clearer by the more detailed description of the invention which follows. The invention described herein relates to novel nitro and cyanoguanidine compounds represented by the following structural formulae (I-IV): EMI2.1 wherein X1 is COCH3, halogen, CN, CH2CN, C(OH)2CF3, OCHF2, OCF3 CH3, SCH3, CF3, NO2, OCF2CHF2, OCH3, N(CH3)2, COOCH3 or CH20R3, where R3 is H or CH3 Y1 is H, halogen, or CH3; Z1 is H, CH3, halogen, OCH3 or CF3; R1 is H or CH3; with the provisos that when X1 is CH3, OCH3, F, C1 or Br and R is H, then Y1 and Zl cannot both be hydrpgen; and when X1 is C1 and Z1 and R are each hydrogen then Y1 cannot be methyl; and the salts or tautomers thereof; EMI2.2 wherein X2 is H, OH, straight or branched C1-C4 alkoxy, SCH3, halogen, OCF3, CF3, straight or branched C1-C4 alkyl or EMI2.3 tetrahydro-2H-pyran-2-yl; Y2 is H or F; Z2 is F, H, CH3 or OCH3; W2 is H or F; mis an integer of O, 1 or 2; R2 is H, CH3, C2H5 or CF3; with the provisos that when m is 0 and R2 is H or CH3, then W2, X2, Y2 and Z2 cannot all be hydrogen; and when m is 1, then R2, W2, X2, Y2 and Z2 cannot all be hydrogen; and the salts or tautomers thereof; EMI3.1 wherein X3 is OCH3, CH3, halogen or CF3; Y3 is H, OH or halogen and Z3 is H or C1; with the provisos that Y3 and Z3 can both be hydrogen only when X3 is OCH3; and when X3 and Y3 are each C1, Br or I, then Z3 cannot be hydrogen; and when X3 is CH3 and Z3 is H, then Y3 cannot be C1; and the salts or tautomers thereof; and EMI3.2 wherein W4 is H or F; X4 is straight or branched C1-C4 alkoxy, straight or branched C1-C4 alkyl or F; with the provisos that when W4 is F, X4 is H; and the salts or tautomers thereof. Among the salt preparations of the present substituted guanidines are included the inorganic alkali metal, alkaline earth metal, Co, Cu, Zn, and Ag salts, along with the organic amine salts represented by the structure, NRaRbRCRd, wherein Ra, Rb, Rc, and Rd are each selected from hydrogen and alkyl C1-C30 straight or branched chain and optionally substituted with one or two -OH, C3-C6 alkenyl or C3-C6 alkynyl groups. Preferred salts of these compounds include the sodium, calcium, magnesium, potassium, ammonium, methylamine, trimethylamine, dodecylamine, tributylamine, diisopropylamine, triethylamine, tetrabutylamine, and tallow-amine salts. The substituted phenylnitroguanidines of the present invention depicted by formula (I) above can be prepared by reaction of an appropriately-substituted aniline with approximately an equimolar amount of an Nalkyl-N-nitroso-N'-nitroguanidine in the presence of an aqueous alcoholic solution. The mixture is then heated to about 400C, treated with a strong base such as sodium hydroxide, and the alcohol removed from the mixture by evaporation. The remaining liquid is then filtered, and the filtrate acidified with a strong mineral acid (i.e., hydrochloric acid) to yield the desired formula (I) substituted phenylnitroguanidine. This reaction is graphically illustrated as follows: EMI4.1 wherein R' is C1-C4 alkyl; R is hydrogen and X1, Y1, and Z1 are as described above. (See McKay and Wright [Journal American Chemical Society, 71:1968 (1949)]). Conversion of the above-identified formula (I) substituted phenylnitroguanidine to the corresponding 2methyl derivative can.be achieved by reaction of the substituted phenylnitroguanidine in which R is hydrogen, with methyl iodide and silver oxide or sodium hydroxide at an elevated temperature. The reaction is graphically illustrated as follows: EMI5.1 wherein X1, Y1, and Z1 are as described above. The formula (II) substituted benzylnitroguanidines may be prepared in the same manner as described for the preparation of the formula (I) substituted phenyl-. nitroguanidines excepting that the appropriatelysubstituted benzylamine is substituted for the aniline. Alternatively, the compounds of formula (II) can be prepared by reacting the benzylamine with nitroguanidine as shown. The product is collected by filtration and recrystallized from the appropriate solvent. EMI5.2 wherein X2, Y2, Z2 and W2 are as described above. (See Davis and Abrams [Proc. Am. Acad. Arts Sci., 61:437 (1926)]). The formula (II) benzylnitroguanidines may also be prepared by reaction of the appropriately-substituted benzylamine with an essentially equivalent amount of a 2alkyl-l(or 3)-nitro-2-thiopseudourea to produce the formula (II) substituted benzylnitroguanidines. Use of a solvent such as ethanol in this reaction is optional. (See Fishbein and Gallahan [Journal American Chemical Society, 76:1877 (1954)] which is illustrated as follows:) EMI6.1 wherein X24 Y2, Z2 and W2 are as described above. Preparation of the substituted phenyl and bentyl cyanoguanidines (III and IV) is readily accomplished by dissolving or dispersing the appropriatelysubstituted aniline or benzylamine in hydrochloric acid and admixing the thus-formed solution or dispersion with an equimolar amount of sodium dicyanamide. In practice, it is generally desirable to disperse the sodium dicyanamide in water prior to admixture with the aniline solution or to disperse the sodium dicyanamide in ethoxyethanol for reaction with the benzylamine. This reaction is illustrated as follows: EMI6.2 wherein R4, Xs, Y5, Z5, W5, m, and n are as previously described. The present invention also relates to methods for regulating plant growth and in particular, for increasing crop yield of underground stem crops, underground stem ornamentals, root crops, graminaceous crops, forage crops, tomatoes, tobacco, sunflowers, cotton, cucurbits, and fruit. This method involves application to the foliage of subject plants or to soil containing the seeds or other propagating organs thereof of a cropyield-enhancing amount of a compound having the following structural formula (V): EMI7.1 wherein W5 is H, F or C1; X5 is H, straight or branched C1-C4 alkyl, halogen, ON, NO2, CH2CH. OCHF2, OCF2CHF2, OCF3, CF3, C1-C4 alkoxy, EMI7.2 tetrahydro-2Hpyran-2-yl, OH, C(OH)2CF3, SCH3, COCH3, N(CH3)2, COOCH3 or CH2OR3, where R3 is H or CH3; Y5 is H, OH, OCH3, CH3 or halogen; Z5, is H, CH3, halogen, OCH3 or CF3 ; R4 is H, CH3, C2H5 or CF3; R5 is H or CH3 ; R6 is NO2 or CN; m is an integer of 0, 1 or 2; n is an integer of 0 or 1; and the salts or tautomers thereof. Compounds depicted by formula (V) above in which X5 is a substituent other than hydrogen; Y5, Zs, n, Rs, and R6 are as described above; m is 0 or 1; R4 is H; and W5 is H, represent preferred crop-yield-enhancing compounds of the present invention. Especially preferred compounds which enhance crop yields are the phenyl compounds depicted by formula (V), wherein n is 0; X5 is CH3, halogen, CF3, OCF3, OCHF2, C(OH)2CF3, or COCH3; Y5 is H, halogen, or CH3; Zs is H, CH3, OCH3, or halogen; R5 is H; R6 is NO2; and W5 is H; provided that when X5 is chloro and Z5 is hydrogen, Y5 cannot be methyl; and the pharmaceutically-acceptable salts or tautomers thereof. Yet another preferred group of crop-yieldenhancing compounds of the invention includes the benzyl compounds depicted by formula (V), wherein n is 1; X5 is H, OCH3, CH3 or halogen; Y5 is H, F or OCH3; Z5 is hydrogen; R5 is H; R6 is NO2; m is 0; R4 is H or CH3; and W5 is H. In addition to the plant-growth-regulating and crop-yield-enhancing actions of the formula (V) compounds, these compounds surprisingly are found to be useful for preserving the freshness and/or inhibiting deterioration of harvested crops, particularly recentlyharvested green fruit, vegetables, and leafy ornamentals, especially recently-harvested edible leafy vegetables such as lettuce, spinach, beet greens, endive, swiss chard, escarole, and chickory. The above-described procedures for the preparation of the formula (I) substituted phenylnitroguanidines and formula (II) substituted benzylnitroguanidines are likewise useful for the preparation of the variously substituted formula (V) nitroguanidines using the appropriate aniline or amine. The reaction may be illustrated as follows: EMI8.1 wherein R6 is NO2; R5 is H; and R4, m, n, Ws, Xg, Ys, and Z5 are as described above. In practice, it has been found that the formula (V) substituted guanidines of the present invention are highly effective crop-yield-enhancing agents when applied in effective amounts to the foliage of crops or to soil containing seeds or other propagating organs, such as corms, rhizomes, bulbs, or seed pieces thereof. Moreover, it has been found that the formula (V) compounds of this invention are especially effective for increasing crop yield of underground stem crops, underground stem ornamentals, root crops, graminaceous crops, forage crops, tomatoes, tobacco, sunflowers, cotton, cucurbits, and fruit; and, further, that crop-yield enhancement can be achieved with both solid and liquid formulations containing the biologically-active formula (V) substituted guanidine. Surprisingly, it has also been discovered that the application of a formula (V) substituted guanidine to the foliage of the above-said crops or to soil containing seeds or other propagating organs thereof, in an amount sufficient to provide about 0.06 to 5.0 kg/hectare (preferably about 0.125 to 2.0 kg/hectare), causes the treated plants to increase the size and/or the number of the tubers, corms, rhizomes, bulbs, kernels, gourds, bolls, or fruit produced thereby. Additionally, it is noted that treatment of underground stem crops, underground stem ornamentals, or root crops with the formula (V) guanidine compounds of the present invention markedly improves uniformity in size and shape of the tubers, corms, rhizomes or bulbs produced by the treated plants. These results ar especially noticeable in potato crops (e.g., white potatoes) wherein treated plants are found to produce: (1) a greater number of potatoes, (2) a substantially increased total weight of potatoes, (3) more superior grade Number 1 potatoes, and (4) fewer Number 2 potatoes. When the formula (V) substituted guanidines are to be applied to harvested fruit, vegetables, or ornamentals to inhibit their deterioration and improve their freshness and shelf life, the formula (V) substituted guanidine is dissolved in water, about 0.01 to 800.0 ppm, and applied as an aqueous solution in the form of a dip or a spray to the fruit, vegetable, or ornamental which is to be protected. For best results, the fruit, vegetables, or ornamentals which are to be protected against rapid deterioration may be sprayed with the aqueous solution containing from 0.01 to 800.0 ppm of the formula (V) substituted guanidine about one to two days before harvest and then either sprayed or dipped in the aqueous solution of the formula (V) guanidine again within about 24 hours following harvest. If multiple applications are impractical, the harvested crop may be dipped or sprayed with an aqueous solution of active ingredient shortly after harvest (preferably within 24 hours following harvest). It has also been found that application of the formula (V) substituted guanidines to the foliage of graminaceous crops such as rice, at the panicle development stage, inhibits lodging of the rice due to adverse weather conditions. The remarkably unique plant-growth-regulant activity of the formula (V) compounds of the present invention is further demonstrated by the physiological alterations noted in tobacco plants that have been treated prior to maturation, preferably between the early seedling stage and plant topping, with a formula (V) substituted guanidine compound. When tobacco plants, approximately 5 to 125 centimeters in height, are treated with about 0.025 to 2.50 kg/hectare (preferably 0.1 to 0.3 kg/hectare) of a formula (V) substituted nitro or cyanoguanidine, senescence in the lower, more mature, tobacco leaves is delayed or retarded until senescence in essentially all of the leaves of the treated plant begins. Thus, harvesting of the mature tobacco leaves can be completed in a single, or in at most, two cuttings, whereas, it had not been uncommon in the past to require three or four cuttings. In addition to these advantages, it is also noted that tobacco plants treated with the formula (V) nitro or cyanoguanidine provide an increased yield of tobacco compared to untreated plants. Although Applicants do not want to be limited by theory, it is seen through experimentation that, as suggested by the preceding discussion, compounds of this invention are true plant-growth regulators, as measured by a number of criteria. Not only are they able to increase crop yields, they are also able to induce regulator effects in laboratory tests. These effects fall into at least three classes of responses, all of which are consistent with the conclusion that these compounds represent a novel class of cytokinins. The observed responses include enhanced growth effects on translocation, as well as enhanced chlorophyll biosynthesis in some tissues with decreased chlorophyll degradation (senescence) in others. These responses suggest that the present class of compounds would be expected to elicit other known cytokinin plant tissue responses in addition to those described below and that a number of uses of these compounds pertaining to translocation of metabolites to storage organs or to temporary storage sites in the tissues or pertaining to delaying senescence and enhancing growth of certain plant tissues are implied from the mode of action of the compounds. The compounds of the present invention have been found to substitute for a well-investigated cytokinin, N6-benzyladenine, in promoting growth of cytokinin-dependent soybean callus in tissue culture. The cucumber cotyledon bioassay, described below, was used to define the compounds which possess cytokinin-like activity. As with many hormone-type bioassays, the response is log-linear with respect to concentration of compound required to elicit a response. The results the present compound had are two-fold, enhanced growth and enhanced rate of chlorophyll biosynthesis. Growth promotive effects also were shown in two other systems as well. The growth of cotyledons could be stimulated in young, whole, radish seedlings with little effect on the growth of the rest of the seedling, that the length of the radicle may be reduced, and a more rapid enlargement in isolated leaf disks from lima bean could be effected. Furthermore, the present compounds also direct the translocation of sucrose within the potato plant from one site to another. Whole potato plants receiving early hydroponic treatment with the present compounds were also found effective in early tuber development in that a greater proportion and weight of larger tubers were evident about half-way through tuber development. Another property of the compounds was observed in senescence retardation of various plant systems. This was manifest by chlorophyll retention in tissues which were otherwise becoming yellow, indicating degrading of chlorophyll. This occurred with application to the foliage in spots or streaks (e.g., potato leaves), in leaf disks of cocklebur or of Romaine leaf lettuce, and in very young potato plants under adverse conditions. The above-identified formula (V) guanidine compounds are highly effective for beneficially altering the growth and/or enhancing the yield of a wide variety of crops, such as: Underground Stem Crops, including: Solanum tuberosum L. - white potato, Helianthus tuberosus - Jerusalem artichoke, Coloeasia antiguorum - Taro, Coloeasia esculenta - dasheen, Allium cepa - onion, Allium sativum - garlic, Allium porrum - leek, Allium schoenoprasum - chive, and Allium ascalowicum - shallot; Underground Stem Ornamentals, including: Corms such as crocus or gladiolus, Bulbs such as tulips and hyacinths, and Rhizomes such as iris, canna or Solomon's seal; Root Crops, including: : Beta vulgaris - common beat, mangels and/or chard, Daucus carota - carrot, Tragopogon porrifolius - salsify, Pastinaca sativa - parsnip Raphanus sativus - radish, Brassica rapa - turnip Brassica napobrassica - rutabaga, Ipomoea batatus - sweet potato, yam, Pioscroa alata - true yam, Manihot esculenta - cassava, and Beta vulgaris - sugar beet; Graminaceous Crops, including: Hordeum vulgare - barley Triticum aestivum - wheat, and Oryza sativa - rice; Cucurbits, including: Cucumis sativus, L. --cucumber, and Cucurbita pepo, L. - pumpkin Fruit, including: Pyrus malus L.- apple; Malvaceae, including: Gossypium hirsutum - cotton, and Lycopersicon esculeutum - tomatoes. Surprisingly, it has also been found that certain of the formula (V) nitroguanidines and cyanoguanidines, for example, those in which Y5 and W5 are hydrogen; Z5 and X5 are halogen; and R4, Rs, R6, m, and n are as described above, are effective for increasing crop yields of rice (Oryza sativa), sunflowers (Helianthus annus, L.), alfalfa (Medicago sativa, L.), forage grasses (such as Agrostis spp., Bromus spp., Dactylis spp., and Pheleum spp.) and tobacco (Nicotiana tobacum, L.). When applied to tobacco plants prior to plant topping, and preferably when the plants are between about 5 cm and 140 cm in height, it has been found that the above-said nitroguanidines or cyanoguanidines retard senescence of the lower, more mature, tobacco leaves until younger leaves at the top of the treated plant are ready for harvest. This treatment represents a great advantage for the tobacco farmers because the number of pickings required for harvesting the crop are reduced. The tobacco from these treated plants is also more uniform than untreated tobacco. These formula (V) compounds have the further advantage, when applied to rice or sunflowers, of increasing stem stiffness and/or stem diameter, thereby inhibiting the incidence of lodging of these crops. Among the most effective compounds found to induce the above-mentioned desirable improvements in crops and crop yields are: l-Nitro-3- (a, a,a-trifluoro-m-tolyl) guanidine; 1- (3, 4-Dichlorophenyl) -3-nitroguanidine; l-(m-Chlorophenyl)-3-nitroguanidine; 1- (3, 5-Dichlorophenyl) -3-nitroguanidine; 1-(4-Chloro-&alpha;,&alpha;,&alpha;-trifluoro-m-tolyl)-3-nitro- guanidine ; l-Nitro-3-(3,5-xylyl)guanidine; 1-(4-Bromo-m-tolyl)-3-nitroguanidine ; 1-Nitro-3-(&alpha;, &alpha;, &alpha;, 4-tetrafluoro-m-tolyl) guanidine ; 1-(3-Chloro-4-fluorophenyl)-3-nitroguanidine ; l-(m-Acetylphenyl)-3-nitroguanidine; -(m-Methoxybenzyl)-3-nitroguanidine; 1-(3,5-Dichlorophenyl)-l-methyl-3-nitroguanidine; 1-Cyano-3-(&alpha;,&alpha;,&alpha;,-4-tetrafluoro-m-tolyl) guanidine ; l-(3-Chloro-4-fluorophenyl)-3-cyanoguanidine; l-Cyano-3-(3,5-dichlorophenyl)guanidine; 1- (3-Chloro-4-hydroxyphenyl) -3-nitroguanidine; l-(m-Methylbenzyl)-3-nitroguanidine; l-Cyano-3-(m-methoxybenzyl)guanidine; l-Nitro-3-veratrylguanidine; l-(m-Fluorobenzyl)-3-nitroguanidine; l-(E-Fluorobenzyl)-3-nitroguanidine; l-(m-Bromophenyl)-3-nitroguanidine; l-Nitro-3-(3 ,4, 5-trichlorophenyl)guanidine; l-(m-Bromophenyl)-3-cyanoguanidine; l-Cyano-3-(a,a,a-trifluoro-m-tolyl)guanidine; l-Benzyl-3-cyanoguanidine; 1- (m-Iodophenyl) -3-nitroguanidine; 1-Nitro-3-[m-(2,2,2-trifluoro-1,1-dihydroxyethyl) phenyl]guanidine; 1- (4-Fluoro-m-tolyl) -3-nitroguanidine; l-Nitro-3-(3,4-xylyl)guanidine; l-(a-Methoxy-m-tolyl)-3-nitroguanidine; l-Benzyl-3-nitroguanidine; 1- (4-Chloro-m-tolyl)-3-nitroguanidine; l-[m-(Difluoromethoxy)phenyl]-3-nitroguanidine; l-Nitro-3-(m-propoxybenzyl)guanidine; 1-(&alpha;-Methylbenzyl)-3-nitroguanidine; 1--(2-Fluoro-5-methylbenzyl)-3-nitroguanidine; l-(2-Fluoro-5-methoxybenzyl)-3-nitroguanidine; and l-Nitro-3-[m-(trifluoromethoxy)phenyl]guanidine. Advantageously, the compounds of the present invention can be formulated as solid or liquid compositions which may be dispersed in a liquid or solid diluent for application to the foliage of plants or to the soil in which they are grown. The substituted guanidines of the invention may be formulated as flowable concentrates, emulsifiable concentrates, wettable powders, dusts, dust concentrates, and granular formulations. A typical flowable liquid concentrate can be prepared by milling together, on a weight basis, about 46% of the substituted guanidine with about 0.4% colloidal magnesium aluminum silicate, about 1.5% naphthalene formaldehyde condensate, about 8% polyethylene glycol, about 0.1% nonylphenol ethylene oxide condensate (9-11 moles ethylene oxide), about 0.1% of a dispersing agent (i.e., sodium lignosulfonate), about 0.07% citric acid, about 46% water, and about 0.06% xanthan gum. This concentrate is dispersed in water for application as a liquid spray. Another flowable liquid concentrate is prepared by admixing or milling together about 40%, by weight, of the substituted nitro or cyanoguanidine, about 0.40% colloidal magnesium aluminum silicate, about 1.50% sodium salts of polymerized alkyl naphthalene sulfonic acids, about 8.0% propylene glycol, about 0.1% ethoxylated octylphenol, about 0.1% nonylphenoxy polyethoxy ethanol, about 0.07% citric acid, about 0.06% xanthan gum, about 0.10% paraformaldehyde and about 49.77% water. Emulsifiable concentrates can be prepared by dissolving, on a weight basis, about 10% of the active guanidine in about 38% of N-methylpyrrolidone, about 35% of a mixture of substituted benzenes, and about 10% of a spreader activator, having ingredients alkylarylpolyoxyethylene glycol, free-fatty acid and propanol, with about 7% by weight of a nonionic surfactant, such as octylphenoxy polyethoxy ethanol, nonylphenoxy polyethoxy ethanol, or the like. This concentrate is dispersed in water for application as a liquid spray. It may also be applied, undiluted to granular carriers, such as corncob grits, kaolin or attapulgite, to provide a granular formulation useful for application to soil in which any of the above-mentioned crops are grown. Emulsifiable concentrates can also be prepared by dissolving, on a weight basis, about 11% of the active guanidine in about 57% of N-methylpyrrolidone, about 24% octyl alcohol, and about 8% polyoxyethylated castor oil. A typical wettable powder can be prepared by grinding together, on a weight basis, about 20 to 45% of a finely-divided carrier (i.e., kaolin, bentonite, diatomaceous earth, attapulgite, or the like), about 45 to 80% of the active compound, about 2 to 5% of a dispersing agent (i.e., sodium lignosulfonate), and about 2 to 5% of a nonionic surfactant (i.e., octylphenoxy polyethoxy ethanol, nonylphenoxy polyethoxy ethanol, or the like). This formulation is generally dispersed in water for application as a liquid spray. Advantageously, the guanidines of this invention may also be prepared as aqueous sprays or dips containing about 0.01 to 800.0 ppm of said guanidine. Said formulations are useful, as such, for treatment of harvested fruit, vegetables, and leafy ornamentals to inhibit their deterioration. To facilitate understanding of the invention, the following nonlimitating examples are presented for the purpose of illustrating the present invention. Unless otherwise noted, all parts are by weight. EXAMPLE 1 Preparation of 1-nitro-3-(3,4,5-trichlorophenyl)guanidine To a slurry of N-methyl-N-nitroso-N'-nitroguanidine 3.3 g (0.0225 mol) in 200 ml of a 50% aqueous ethanol mixture is added 5.0 g (0.025 mol) of 3,4,5trichloroaniline. This mixture is heated to 400C for 72 hours and then treated with one equivalent of NaOH to decompose excess N-methyl-N-nitroso-N'-nitroguanidine. The mixture is then filtered and acidified with concentrated HC1 to give 1.6 g of a yellow solid which, when recrystallized, gives 1.4 g of the desired product. The melting point of the product is 209.50C dec. The above procedure can be repeated except that the appropriate aniline is substituted for 3,4,5trichloroaniline, and the period of heating is adjusted to yield the substituted nitroguanidines reported in Table I below. The reaction may be illustrated as follows: EMI18.1 TABLE 1 EMI19.1 X1 Y1 Z1 Melting Point ( C) F H H 172 - 174 Cl H H 162 - 163 Br H H 180 - 181 I H H 183 - 186 CF3 H H 154.5 - 155.5 CH3 H H 122 - 124 CH2CN H H 165 - 167 CH2OCH3 H H 106 - 107.5 CH2OH H H 138 - 140 COCH3 H H 158 - 160 COCF3.H20 H H 172 - 174 SOH3 H H 155 - 157 OCHF2 H H 122 - 124 OCF3 H H 135 - 136.5 OCF2CHF2 H H 158 - 160 OCH3 H H 151.5 - 153.5 OC2H5 H H 137.5 - 139 TABLE I (Continued) X1 Y1 Z1 Melting Point ( C) CN H H 207 - 208 NO2 H H 194 - 196 H H H N(GH3)2 H H 158 - 159.5 COOCH3 H H 173 - 175 C1 F H 171 - 173 C1 C1 H 155 - 156.5 Cl CH3 H 176 - 177 CF3 F H 168 - 170 CF3 Cl H 212 - 213 CH3 F H 182 - 183.5 CH3 Br H 182 - 183 CH3 Cl H 196.5 - 198 CH3 CH3 H 161 - 162.5 Cl H Cl 218 - 219 Br H Br 243 dec. Br H CH3 201 - 203 CH3 H CH3 188 - 189 OCH3 H CF3 152 - 154 CF3 H CF3 224 - 226 OCH3 H OCH3 208 - 209 Cl Cl Cl 210 dec. TABLE I (Continued) X1 Y1 Z1 Melting Point ( C) COOH H H 245 - 47 OC6H5 H H 138 - 39.5 H Br H 189 - 191 H CF3 H 170 - 72 H CH2COOH H 199 - 200.5 H OCF2CHF2 H 152 - 53.5 N02 F H 171 - 72 Cl CH30 H 185.5 - 86.5 NH2 CH3 H 170.5 - 72.5 CH3 CH3 CH3 207 - 09 EXAMPLE 2 Preparation of 1-(3,5-dichlorophenyl)-2-methyl-3-nitro guanidine PART A EMI22.1 Methyl iodide (10 ml) is added to the nitroguanidine (2 g, 0.008 mol) and silver oxide (0.92 g, 0.004 mol), and the suspension refluxed. After two hours, the black suspension gradually becomes a yellow suspension. It is cooled to room temperature and filtered through diatomaceous earth. After concentration in vacuo, the crude product is recrystallized from Et20/THF to give 1.6 g (76%) of-a white solid with melting point 13600. - 13800. This procedure is also effective for preparing l-methyl-3-nitro-1-(a,a,a,4-tetrafluoro-m- tolyl)guanidine, melting point 16900 - 17100. PART B Preparation of 1-(4-Bromo-m-tolyl)-l-methyl-3-nitro- guanid ine EMI22.2 Sodium hydroxide (50% aq, 0.94 ml, 0.012 mol) is added in one portion to a homogeneous mixture of phenylnitroguanidine (3.00 g, 0.011 mol) and aqueous ethanol (5:1 ethanol:water, v/v). Methyl iodide (4.79 ml, 10.9 g, 0.077 mol) is added and the resultant mixture is stirred for 22 hours at 250C. The white precipitate is filtered with water wash and recrystallized from ethanol to afford pure product (2.35 g, 74.6%, melting point 16200 - 1640C). PART C Preparation of l-benzyl-l-methyl-3-nitroguanidine EMI23.1 N-Methylbenzylamine (9.89 g, 0.082 mol) is added dropwise to a suspension of MNNG (10.0 g, 0.068 mol) in aqueous ethanol (1:1 ethanol:water, v/v) at 250C. A gradual exotherm to 440C occurs over the next 15 minutes. After stirring for 42 hours at ambient temperature, the white slurry is filtered. The resultant white solid (7.13 g) is recrystallized from hexanes:ethanol to-afford pure product (white crystals, 6.06 g, 43.0%, melting point 1030C - 1070C). EXAMPLE 3 Preparation of l-(m-fluorobenzyl)-3-nitroguanidine The compound m-fluorobenzylamine (7.5 g, 0.06 mol) is added to a slurry of N-methyl-N-nitroso-N' nitroguanidine (8.33 g, 0.056 mol) in a 50% aqueous ethanol mixture. The thus-formed mixture is stirred for 18 hours, then treated with 1N NaOH (150 ml), and the mixture filtered. The filtrate is acidified with concentrated HC1, and the reaction mixture is then filtered to obtain the desired fluffy white solid product (10.6 g) having a melting point of 17700 - 17900. The above procedure is repeated using the appropriately substituted amine and 2-methyl-l(or 3)-nitro2-thiopseudourea to obtain the compounds illustrated in Table II below. The reaction is graphically illustrated as follows: EMI24.1 wherein m, R2, W2, X2, Y2, and Z2 are as defined above. TABLE II EMI25.1 EMI25.2 <tb> W2 <SEP> X2 <SEP> Y2 <SEP> Z2 <SEP> R2 <SEP> m <SEP> Melting <SEP> Point <SEP> (OC) <tb> H <SEP> H <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 179 <SEP> - <SEP> 180.5 <tb> F <SEP> H <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 181 <SEP> - <SEP> 183 <tb> H <SEP> OH <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 122 <SEP> - <SEP> 125 <tb> H <SEP> OCH3 <SEP> . <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 134 <SEP> - <SEP> 136 <tb> H <SEP> OC2H5 <SEP> k <SEP> H <SEP> H <SEP> 0 <SEP> 125 <SEP> - <SEP> 128 <tb> H <SEP> C3H7-n <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 140.5 <SEP> - <SEP> 141.5 <tb> H <SEP> OC4Hg-s <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 93 <SEP> - <SEP> 98 <tb> <SEP> X)- <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 110.5 <SEP> - <SEP> 113 <tb> H <SEP> oyD <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> lI0.5 <SEP> - <SEP> 113 <tb> H <SEP> OCF3 <SEP> H <SEP> H <SEP> H <SEP> O <SEP> 138 <SEP> - <SEP> 139 <tb> H <SEP> SCH3 <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 149 <SEP> - <SEP> 152 <tb> H <SEP> F <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 177 <SEP> - <SEP> 179 <tb> H <SEP> C1 <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 166 <SEP> - <SEP> 167 <tb> H <SEP> Br <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 157 <SEP> - <SEP> 159 <tb> H <SEP> I <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 167 <SEP> - <SEP> 169 <tb> H <SEP> CH3 <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 151 <SEP> - <SEP> 153 <tb> H <SEP> 02115 <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 119 <SEP> - <SEP> 120.5 <tb> H <SEP> CF3 <SEP> H <SEP> H <SEP> H <SEP> 0 <SEP> 164 <SEP> - <SEP> 165 <tb> H <SEP> H <SEP> F <SEP> H <SEP> ' <SEP> H <SEP> O <SEP> 205 <SEP> - <SEP> 206 <tb> H <SEP> H <SEP> C1 <SEP> H <SEP> . <SEP> H <SEP> 0 <SEP> 195 <SEP> - <SEP> 197 <tb> H <SEP> H <SEP> Br <SEP> H <SEP> H <SEP> 0 <SEP> 172 <SEP> - <SEP> 174 <tb> TABLE II (continued) W2 X2 Y2 Z2 R2 m Melting Point ( C) H H CH3 H H 0 181 - 183 Cl Cl H H H 0 220 - 222 F CH3 H H H 0 198 - 198.5 F OCH3 H H H 0 162 - 165 Cl H Cl H H 0 200 - 202 F H F H H 0 209 - 211 F H H CH3 H 0 171.5 - 173 F H H F H 0 186 - 188 F H H OCH3 H 0 149 - 151 F H H H H 1 153.5 - 154.5 H OCH3 H H H 1 88 - 89 H OCH3 H H H 2 122 - 123 H H H H CH3 0 115 - 116.5 H H H H CF3 0 149 - 151 H H H H C2H5 0 129.5 - 130.5 F H H H CH3 0 99 - 102 H H H H CH3 O (+) isomer 126 - 127 H H H H CH3 O (-) isomer 127.5 - 128 H CH3 H H CH3 0 140 - 143 H OCH3 H H CH3 0 126 - 130 H H F H CH3 0 133 - 136 TABLE II (Continued) w2 X2 Y2 Z2 R2 m MElting Point ( C) C1 H H H H 0 168 - 170 OCH3 H H H H 0 202 - 205 H CN H H H 0 206 dec. H OC6H5 H H H 0 145 - 147 H COOCH3 H H H 0 158 - 162 H CH2CH2COOC2H5 H H H 0 77 - 79 H OSO2CH3 H H H 0 134 - 137 H H OCH3 H H 0 191.5 - 192.5 H H N(CH3)2 H H 0 211 - 213 H H CH2N(CH3)2 H H 0 136 - 144 H H CH2NH2 H H 0 2600 H H CH2CH2COOC2H5 H H 0 124 - 126 H H ON H H 0 166 - 168 OCH3 H OCH3 H H 0 200 - 201 H H H H C6H5 0 236 - 237 H F H H CH3 0 135 - 138 H OCH3 OCH3 H H 0 152.5 - 153.5 H Cl Cl H H 0 208 - 210 H -O-CH2-O- H H 0 207.5 - 209 H OCH3 H OCH3 H 0 166 - 168 H CH3 H CH3 H 0 178 - 180 H Cl H Cl H 0 218 - 219 H H H H CH3 1 178 - 180 H H H H CH2C6H5 0 199.5 - 201 OCH3 H H H CH3 0 188 - 192 EXAMPLE 4 Preparation of l-cyano-3-(3,5-dichlorophenyl)guanidine To a solution of 4.45 g (0.05 mol) of sodium dicyanamide in 50 ml of 1N HC1 is added 8.1 g (0.05 mol) of 3,5-dichloroaniline in 50 ml of H20. The mixture is heated to about 800C to 1000C for two hours. The mixture is then cooled, and the precipitated solids are recovered by filtration, washed and dried to give 8.75 g of the desired product having a melting point of 19600 - 19800. Following the above procedure, but substituting the appropriately substituted aniline for 3,5-dichloroaniline, provides the compounds reported in Table III below. The reaction may be graphically illustrated as follows: EMI28.1 wherein X3, Y3, and Z3 are as described above. TABLE III EMI29.1 X3 Y3 Z3 Melting Point ( C) H H H 195 - 196 CF3 H H 203 - 206 Cl H H Br H H 236 - 237 NO2 H H 234 - 236 OCH3 H H 182 - 184 CH3 H H CN H H 234 - 235.5 Cl OH H Cl F H 214.5 - 216 CF3 Cl H 194 - 196 CF3 F H 146 - 148 CH3 Br H 223 - 225 Cl CH3 H 232 - 234 Cl Cl H 226 - 229 Cl H Cl 196 - 198 TABLE III (Continued) X3 Y3 Z3 Melting Point ( C) COCH3 H H 175 - 178 COOH H H N(CH3)2 H H 163.5 - 164.5 COOCH3 H H 212 - 213 H Cl H H OCH3 H H NHCOCH3 H H CH3 H H N(CH3)2 H H OH H H COOH H H COCH3 H H # N(C2H5)2 H CH3 CH3 H CH3 H CH3 224 - 227 CF3 H CF3 263 - 265 Following the procedure of Example 4, but substituting the appropriately-substituted benzylamine for 3,5-dichloroaniline, provides the compounds reported in Table IV below. The reaction may be illustrated as follows: EMI31.1 wherein W4 and X4 are as described above. TABLE IV EMI31.2 W4 # m X4 Y4 Z4 R2 Melting Point ( C) H O H H H H 100 - 101 F O H H H H 129 - 130 H O OCH3 H H H 112 - 114 H O CH3 H H H 97 - 98.5 H O F H H H 134 - 136 H O H Cl H H 153 - 155 H O H F H H 134 - 135 F O H H CH3 H 123 - 124 F O H H OCH3 H 129 - 131 H O H Cl H CH3 171 - 174 H O H H H CH3 156 - 158 EXAMPLE 5 Cucumber cotyledon greening bioassay for cytok in ins To evaluate test compounds for cytokinin stimulation in cucumber plants, plant cucumber seeds (Na tional Pickling variety), placed in covered plastic trays, were soaked in moist vermiculite and were exposed to a green safelight. The trays were then placed in a dark environment for six days at 300C, Test solutions of compounds were prepared according to a 1 to 8 dilution series including 0.0156 ppm, 0.125 ppm, 1.0 ppm, 8 ppm, and 64 ppm of test compound. The solutions all contained 40 mM KC1, glassdistilled H20, and up to 1.25% acetone. (The compounds were initially dissolved in 100% acetone). Ten ml of diluted compound were placed in a 10 cm petri dish containing three layers of Whatman i1 cellulose filter papers. Again using dim green light, the cotyledons from the seedlings were excised using great care to discard the hook region, and eight pairs (16 cotyledons) were placed in each dish with the inner (upper) cotyledon surfaces downward. These were then incubated in the dark at 300C overnight (17 to 21 hours). These were placed in the dishes under fluorescent light, with an intensity of 12-14W per square meter, for a period of three hours. The dishes were kept at 200C or less in the dark while the cotyledons were sequentially collected and put into lots in large test tubes containing 5 ml of dimethylformamide. The tubes were sealed with Parafilm and placed at 40C in the dark, overnight, or at 300C in the dark for four hours to extract the chlorophyll. The leachate was analyzed for absorbance at 663 nanometers (nm). The cotyledons were removed and their surface areas were measured with a leaf-area meter. Data obtained with N6-benzyladenine, a known cytokinin, were used to establish conditions for the test and to depict the cytokinin-like responses of the test compounds. Graphic curves were drawn to show (1) the increase in rate of chlorophyll biosynthesis (absorbance of leachate at 663nm), and (2) the increase in cotyledon surface area (expansion). These data are presented below in graphs I and II. . A compound of the present invention, l-nitro-3 (a,a,a,4-tetrafluoro-m-tolyl)guanidine, is also evaluated in this test. A curve of the two responses obtained is compared with N6-benzyladenine (a "Standard Cytokinin" against which other compounds can be compared). Graph I reports greening data obtained in this test with the above-said compounds. Graph II shows the expansion of the surface area of the cotyledon obtained with said compounds. The following dose-response curves show that both N6-benzyladenine and l-nitro-3-(a,a,a14-tetrafluoro- m-tolyl)guanidine are active in this bioassay. * These procedures are similar to those described by "Fletcher et al, 1982 Plant Physiology, 69:675-677 and Moran and Porath, 1980 Plant Physiology." GRAPH I Dose-response increase in rate of chlorophyll biosynthesis (absorbance of leachate at 663 nm@) obtained with N6-benzyladenine and a compound of the invention 1-nitro-3-(&alpha;,&alpha;,&alpha;,4-tetrafluoro-m-tolyl)- guanidine EMI34.1 Greening = chlorophyll biosynthesis nm = nanometer GRAPH II Dose-response increase in cotyledon surface area obtained with N6-benzyladenine and 1-nitro-3 (&alpha;,&alpha;,&alpha;,4-tetrafluoro-m-tolyl) guanidine. EMI35.1 N6-BA = N6-benzyladenine Guanidien = 1-nitro-3-(&alpha;,&alpha;,&alpha;,4-tetrafluoro-m-tolyl) guanid ine ANALOG TEST RESULTS-CUCUMBER COTYLEDON BIOASSAY Compounds with moderate to excellent activity are listed below, along with the concentration of the compound, in parts per million, which is required to achieve 50% of the maximum response. CUCUMBER COTYLEDON BIOASSAY FOR CYTOKININS Compound ED50, PPM 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4-tetra fluoro-m-tolyl)guanidine 0.48 l-(m-Methoxybenzyl)-3nitroguanidine 1.8 l-(3, 5-Dichlorophenyl)- 3-nitroguanidine 0.125 l-Nitro-3-(a, a, a-tri- fluoro-m-tolyl)guanidine O,f25 l-Cyano-3-(a, a, a'-tri- fluoro-m-tolyl) guanidine 0.22 l-Nitro-3-phenylguanidine 8.0 l-Benzyl-3-nitroguanidine 5.7 l-(m-Chlorobenzyl)-3- nitroguanidine 3.8 l-Cyano-3-(a,a,a,4-tetrafluoro-m-tolyl)guanidine 2.5 l-(m-Methoxyphenyl) -3- nitroguanidine 1.0 l-(m-Iodophenyl)-3nitroguanidine 0.125 l-(m-Bromophenyl)-3nitroguanidine 0.48 Compound ED50, PPM l-(m-Bromophenyl)-3- cyanoguanidine 1.0 l-(m-Chlorophenyl)-3nitroguanidine 1.8 l-(m-Chlorophenyl)-3 cyanoguanid ine 1.8 1-(m-Fluorophenyl)-3nitroguanidine 8.0 l-Nitro-3-m-tolylguanidine 1.0 l-Cyano-3-m-tolylguanidine 1.0 l-Cyano-3-(a, a, a-trifluoro- m-tolyl)guanidine 0.22 1-(m-Methoxyphenyl)-3nitroguanidine 1.0 l-[m-(Difluoromethoxy)- phenyl3-3-nitroguanidine 0.06 1-Nitro-3- [m-(trifluoro- methoxy)phenyl]guanidine 3.8 l-[m-(Methylthio)phenyl]3-nitroguanidine 1.0 l-(m-Ethoxyphenyl)-3nitroguanidine 3.8 1-Nitro-3-[m-(1,1,2,2tetrafluoroethoxy) phenyl]guanidine 0.48 l-(-Hydroxy-m-tolyl)- 3-nitroguanidine 2.5 Compound ED50, PPM 1- (a-Methoxy-m-tolyl) - 3-nitroguanidine 1.8 1-Nitro-3-[m-(2,2,2trifluoro-l,l-dihydroxyethyl) phenyl guanidine 0.48 Methyl-m-(3-nitroguanidine)benzoate 3.8 l-(m-Acetylphenyl) -3- nitroguanidine 3.8 l-(m-Cyanophenyl)-3nitroguanidine 1.0 l-(m-Cyanophenyl)-3- cyanoguanidine 8.0 1-[m-(Cyanomethyl)phenyl]-3-nitroguanidien 3.8 1-(m-Nitrophenyl)-3nitroguanidine 8.0 l-[m-(Dimethylamino)- pbenyl]-3-nitroguanidine 3.8 l-Cyano-3-(m-methoxyphenyl)guanidine 2.5 1- (3-Chloro-4-fluoro- phenyl)-3-nitroguanidine 1.8 1- (3-Chloro-4-fluoro- phenyl)-3-cyanoguanidine 14.0 l-(3, 4-Dichlorophenyl)- 3-nitroguanidine 1.0 1-(4-Bromo-m-tolyl)3-nitroguanidine 1.0 Compound ED5O, PPM 1-(4-Chloro-m-tolyl)3-nitroguanidine 1.8 l-(4-Fluoro-m-tolyl)- 3-nitroguanidine 3.8 1-Nitro-3-(3,4-xylyl) guanid ine 3.8 1-(4-Chloro-&alpha;,&alpha;,&alpha;-tri- fluoro-m-tolyl)-3-nitro guanid ine 1.0 1-(3,5-Dibromophenyl)3-nitroguanidine 0.125 1-(3,5-Dichlorophenyl)3-nitroguanidine 0.125 l-(3, 5-Dichlorophenyl)-l- methyl-3-nitr9guanidine 3.8 l-Cyano-3-(3,5-dichlorophenyl)guanidine 0.48 1-(3,5-Dimethoxyphenyl)- 3-nitroguanidine 14.0 I-(5-Bromo-m-tolyl)-3nitroguanidine 0.48 l-Nitro-3-(3,5-xylyl) guanid ine 3.8 1-(&alpha;,&alpha; ;,&alpha;,&alpha;', &alpha;',&alpha;'-Hexa- fluoro)-3,5-xylyl)-3nitroguanidine 3.8 1-(2-Fluoro-3-methoxybenzyl)-3-nitroguanidine 2.5 1-Nitro-3-(3,4,5-tri chlorophenyl)guanidine 3.8 1-(4-Chloro-&alpha;,&alpha;,&alpha;-tri- fluoro-m-tolyl)-3 cyanoguanid ine 2.5 Compound ED50, PPM l-(o-Fluorobenzyl)-3 nitroguanid ine 3.8 l-(m-Iodobenzyl)-3nitroguanidine 14.0 l-(m-Chlorobenzyl)- 3-nitroguanidine 3.8 l-(m-Bromobenzyl) 3-nitroguanid ine 5.7 l-(m-Fluorobenzyl)3-nitroguanidine 8.0 l-(m-Methylbenzyl)- 3-nitroguanidine 8.0 l-Cyano-3-(m-methylbenzyl) guanidine 8.0 l-(Nitro-3-[m-(trifluoro- methyl)benzyl]guanidine 8.0 l-(m-Methoxybenzyl)-3- nitroguanidine 1.8 l-Cyano-3-(m-methoxy benzylOguanidine 2.5 1-(m-Hydroxybenzyl)3-nitroguanidine 1.0 1-(m-Ethoxybenzyl)3-nitroguanidine 8.0 l-Nitro-3-(m-propoxybenzyl)guanidine 1.3 1-(m-sec-Butoxybenzyl)3-nitroguanidine 0.31 l-(2-Fluorobenzyl)-3- nitroguanidine 8.0 Compound ED50, PPM 1-Nitro-3-(m[(tetra hydro-2H-pyran-2-yl)oxyj - benzyl] guanidine 1.0 1-(2, 5-Difluorobenzyl) - 3-nitroguanidine 5.7 l-(2-Fluoro-5-methoxy- benzyl)-3-nitroguanidine 2.5 1-(2-Fluoro-5-methylbenzyl)-3-nitroguanidine 8.0 1-(2,4-Difluorobenzyl)3-nitroguanidine 10.6 1-(2,4-Dichlorobenzyl)3-nitroguanidine 8.0 l-(a-Methylbenzyl)-3nitroguanidine 1.8 l-(m-a-Dimethylbenzyl)3-nitroguanidine 14.0 l-(o-Fluorophenethyl)3-nitroguanidine 14.0 l-(m-Methoxyphenethyl) - 3-nitroguanidine 14.0 l-Nitro-3-[a-(trifluoromethyl)benzyllguanidine 2.5 l-(a-Ethylbenzyl)-3- nitroguanidine 0.22 EXAMPLE 6 Tissue culture test to establish cytokinin mode of action Cytokinins are involved with plant cell division. To specifically test for cytokinin-like activity of an unknown compound, said compounds must be able to substitute for a known cytokinin by allowing a cytokinindependent tissue culture to grow on a defined medium. Callus cultures derived from cotyledon tissue of soybeans (variety Acme) require a cytokinin in order to grow on agar media. These callus cultures are used in this evaluation to determine whether the compounds of the invention promote cell division. Callus is prepared by subculturing on a basal medium containing vitamins, mineral salts, 3% sucrose, 0.95 agar, and naphthalene acetic acid at 2 ppm (PNAS 54:1052-8 (1965)). The addition of 10-7M N6-benzyladenine is normally required for callus to grow. Test media is prepared by omitting the known cytokinin (N6-BA) and substituting test compounds at various concentrations. Four replicate dishes are used per test solution. Into 15 x 60 mm plastic Petri dishes is poured 6 ml of agar media containing test compounds. Callus is scraped from subculture plates, gently broken into small pieces and mixed with dilute agar in basal medium. Then, 2 ml of this is layered onto each test medium. After eight days at 250C, in the dark, the dishes are examined for growth of the callus on the various èst media. The data obtained are reported in Table IV below. TABLE IV GROWTH PROMOTION OF A CYTOKININ-DEPENDENT TISSUE CULTURE ON A DEFINED MEDIUM Concentration Percent of Callusa Compound (PPM) ¯ Which Is Growing Untreated control 0 0.3 1-(3,5-Dichloro- 0.1 4.0 phenyl)-3-nitro- 0.3 100.0 guanid ine 1.0 100.0 l-Nitro-3-(a,a,a,4- .0.3 8.0 tetrafluoro-m-tolyl)- 1.0 100.0 guanidine 3.0 100.0 10.0 100.0 l-(m-Methoxybenzyl)- 3.0 15.0 3-nitroguanidine 10.0 100.0 30.0 100.0 100.0 100.0 N6-benzyladenine 10-7 M 100.0 a = Growth is measured visually by comparing small brown cell clusters (not growing) to those which are large and white (growing). It is seen that the compounds of the present invention do replace N6-benzyladenine, thereby, indicating cytokinin-like activity. EXAMPLE 7 Antisenescence properties on disks of leaf lettuce Leaf disks are prepared from locally-purchased Romaine lettuce. The disks (4 per treatment) are placed in Petri dishes containing Whatman &num;1 filter papers and test solutions containing 10 ppm of test compound (with 0.2% acetone) or 100 ppm of test compound (with 2% acetone) in H2O. After five days at room temperature in the dark, the disks are extracted with dimethylformamide, and absorbance of chlorophyll is measured at A 663 nm. Data obtained are reported in Table V. TABLE V ANTI SENESCENCE PROPERTIES OF TEST COMPOUNDS APPLIED TO LEAF DISKS OF LEAF LETTUCE Percent Increase In Concentration Chlorophyl Retention Treatment (PPM) Over Untreated Controls m-Trifluoromethylphenyldicyandiamide 100 18 l-Benzyl-3-nitro- 10 18 guanidine 100 17 l-Nitro-3- (a, a, a-tri- fluoro-m-tolyl)guanidine 100 16 1(3, 5-Dichlorophenyl) - 3-nitroguanidine 10 14 l-Nitro-3-(a,a,a,4-tetra- fluoro-m-tolyl)guanidine 10 40 l-(m-Methoxybenzyl)-3- 10 11 nitroguanidine 100 15 l-Oyano-3-(a,a,a,4-tetra- 10 33 fluoro-m-tolyl)guanidine 100 17 l-(m-Methoxyphenyl)-3- 10 17 nitroguanidine 100 3.4 l-Cyano-3-(m-Methoxy- 10 40 benzyl)guanidine 100 26 l-Nitro-3-[m-(trifluoro- methyl)benzyl]guanidine 10 26 l-Nitro-3-phenylguanidine 10 10 Lettuce leaf disks treated with the present compounds enhance chlorophyll retention about 10% to 40% over untreated controls. EXAMPLE 8 Enlargement of leaf disks of lima bean In this evaluation, lima bean leaf disks are found to respond to various compounds of this invention by increasing the growth of the disks when exposed to aqueous solutions of test compounds. Five or six leaf disks (combined area of 2.2 sq. cm) are placed in 15 x 100 mm Petri dishes with three layers of Whatman &num;1 filter paper and-12 ml of 40 mM KC1, plus various concentrations of test compounds. The dishes are kept in the light for six days, then disk area is measured with an area meter. Several of the test compounds are found to increase the mount of growth exhibited by the lima bean leaf disks. These data are reported in Table VI below. TABLE VI ENHANCED ENLARGEMENT OF LEAF DISKS OF LIMA BEANS Concentration Percent Increase Treatment (PPM) in Leaf Disk Area Control 0 54 1-Cin-Methoxyphenyl)- 0.12 87 3-nitroguanidine 1.0 103 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4- tetrafluoro-m-tolyl)- 1.0 92 guanid ine 8.0 107 EXAMPLE 9 Determination of growth-promoting effects of nitroguanidines and cyanoguanidines on radish seedlings in liquid culture In this evaluation, surface-sterilized radish seeds, variety Cherry Belle, are asceptically placed in 125 ml Erlenmeyer flasks containing 20 ml autoclaved medium. The medium contains distilled water, mineral salts such as those used for plant tissue cultures (300 mg/l KH2P04, 65 mg/l KC1, 4.9 mg/l MnS04 H20; 2.7 mg/l ZnSO4; 7H20; 1.8 mg/l H3B03; 0.8 mg/l; 0.35 mg/l CuS04 5H20; 0.1 mg/l (NH4)6M07024 4H2O; 499 mg/l Ca(N03)2. 04H20; 1 g/l KN03; lg/l NH4NO3; 71 mg/l MgS04 7H2O; and 42 mg/l commercial 10% iron chelate), and an appropriate dilution of test compound prepared from a stock solution of 5000 ppm (technical compound) in acetone. The medium pH is adjusted to 5.8 before autoclaving, and the test compound is added after autoclaving of the medium, just prior to adding the 10 to 20 seeds per flask. Flasks are incubated on a reciprocating shaker for six days under dim fluorescent light at room temperature. At this time, seedlings are removed, blotted, and dissected into various organs which are weighed (fresh weight) and/or assessed for chlorophyll content. Data obtained are reported in Table VII. TABLE VII GROWTH PROMOTING EFFECTS OF NITROGUANIDINES AND CYANOGUANIDINES ON RADISH SEEDLINGS Percent Change In Fresh Concentration Weight of Radish Cotyledons Treatment (PPM) Over Untreated Controls Untreated controls 0 l-(3,5-Dichloro- 0.001 v - 4 phenyl)-3-nitro- 0.003 - 4 guanidine 0.01 +24 0.03 +64 0.1 +92 0.3 +151 It can be seen that there is a 20% to 150% increase in radish cotyledon weights in comparison to untreated controls when 0.01 to 0.5 ppm 1-(3,5-dichlorophenyl)-3nitroguanidine is used to treat said radish cotyledons. EXAMPLE 10 Early increase in development of tubers of potato, Solanum tuberosum, variety Superior In greenhouse tests, young potato plants whose roots have-been exposed to test compounds of the inventin via hydroponic treatment for 48 hours have larger tubers early in tuber development than do untreated plants. This suggests that under field conditions, treated plants could produce.more tubers that would reach the status of U. S. No. l's. In these tests, potato plants, variety Superior, are grown in vermiculite until they are 7 cm tall. They are then treated hydroponically with aqueous solutions of test compound at various concentrations for 48 hours. Thereafter, the potato plants are planted in greenhouse soil and grown for two months before evaluation. Four plants are used per treatment. In plants treated with test compounds, more tubers with weights above 2 oz. are in evidence early in tuber development. In untreated plants, 20% (w/w) of the young tubers are in this weight class while in treated plants, 29 to 81% (w/w) of the tubers are in this class. For perspective, the tubers weighing over 2 oz. have probably reached 40 to 60% of their expected weight, were they to become U. S. &num;l's. Data obtained are reported in Table VIII below. TABLE VIII EARLY INCREASE IN SIZE OF DEVELOPING TUBERS OF POTATO, VARIETY SUPERIOR Tubers Weighing Over 2 oz. (55 g) Treatment Concentration Total Weight Percent Increase (PPM) (g) Over Untreated Percent of Total Controls Tuber Weight Untreated control 0 77 0 20 1-(3,5-Dichlorophenyl)- 0.1 175 127 52 3-nitroguanidine 1.0 240 217 57 1-Nitro-3-(&alpha;,&alpha;,&alpha;-tri- 0.1 102 32 29 fluoro-m-tolyl)guanidine 1.0 140 82 41 10.0 419 184 81 1-(m-Methoxybenzyl)- 1.0 107 39 32 3-nitroguanidine 10.0 108 40 29 100.0 182 136 64 EXAMPLE 11 Evaluation of test compounds for inhibiting lodging of paddy rice In this evaluation, IR-36 paddy rice is transplanted into 12 m2 plots in four replicates at the rate of three seedlings per hill. Hill spacing is 25 x 25 cm. A basal application of fertilizer N,P,K at 60, 40, and 40 kg/ha is made and followed by an additional application of nitrogen (30 kg/ha) 30 and 50 days after the plots are sprayed with an aqueous-acetone mixture (20/80) of test compound containing 0.25% of a nonionic wetting agent (i.e., nonylphenol containing 9 mols of ethylene oxide, oleic acid, and isopropanol). Application of test compound is made at the panicle development stage approximately equivalent to Zadok's stage Z31/32. These evaluations are conducted in an area where lodging pressure is normally severe. During the growing season, water is maintained in the paddies at a depth of about 3 to 5 Four months after transplanting, the plots are examined, and the rice harvested from 6 m2 sampling areas. Data obtained are reported below. Concentration Percent Treatment ¯ kg/ha Lodging Untreated control 0 100 l-(3,5-Dichlorophenyl)- 1 20 3-nitroguanidine 2 10 4 5 EXAMPLE 12 Evaluation of test compounds for increasing yield in paddy rice The procedure of Example 11 is repeated except that the aqueous-acetone mixture containing test compound is applied to transplanted IR-36 paddy rice when it reaches the maximum tillering stage. Also, the aqueous-acetone (20/80) mixture containing test compound and nonionic wetting agent is applied to the tillered rice at rates sufficient to provide 11, 33, or 100 g/ha of test compound. About four months after transplanting, the rice is harvested, with the resultant data reported below. RICE YIELD ENHANCEMENT Yield Rate Yield,* . Percent Treatment g/ha Ton/ha of Control Untreated control - 4.46 100 l-Potassium-3-(3,5- 11 5.21 117 dichlorophenyl)-l- 33 4.70 105 nitroguanidine 100 4.58 103 *at 14% moisture EXAMPLE 13 Evaluation of test compounds for increasing grain yield in wheat and barley Surprisingly, it is also noted that these compounds are effective for inducing early maturation of grains such as wheat and barley. During the third week of May, fields previously plowed, harrowed, and fertilized with 896 kilograms/hectare of a 9:9:9 chemical fertilizer are seeded in one section with 2.44 hectoliters/hectare of Spring wheat (variety Sinton). In another section, the field is seeded with 2.09 hectoliters/hectare of Spring barley (variety Herta). Each field is staked out in 12 square meter plots. When the plants reach the 230/231 Zodak's stage, the plots are then sprayed with an 80:20 acetone/water mixture containing 0.25I of a nonionic wetting agent (i.e., nonylphenol containing 9 mols of ethylene oxide, oleic acid, and isopropanol) and a sufficient amount of test compound to provide 0 (untreated control), 0.22, 0.67, or 2.0 kg/ha of said test compound. Each treatment is replicated five times. Seven weeks after planting, the plots are harvested. The harvested grain is then normalized to 15% moisture content and weighed. Data obtained are reported in Table IX below. TABLE IX EVALUATION OF TEST COMPOUNDS FOR INCREASING GRAIN YIELD IN WHEAT AND BARLEY Rate Grain Yield Compound Crop Kg/Ha Hectoliters/Hectare Percent of Control 1-(3,5-dichlorophenyl) - Spring O (control) 25.84 3-nitroguanidine Wheat 0.22 29.84 115 0.67 30.80 119 2.0 29.32 113 1-(3,5-Dichlorophenyl- Spring 0 (control) 22.62 2-methyl-3-nitro- Wheat 0.22 25.14 111 guanidine 0.67 26.19 116 2.0 24.80 110 1-(3,5-Dichlorophenyl)- Spring o (control) 30.10 3-nitroguanidine barley 0.22 32.90 108 0.67 33.20 109 2.0 34.80 114 EXAMPLE 14 Evaluation of test compounds as yield-enhancing agents for cotton (Gossypium hirsutum cv Acala) In this evaluation, a field, previously plowed, harrowed, and fertilized, is seeded with cotton (Gossypium hirsutum cv Acala) during the third week of April. Plantings are made to provide approximately one meter spacing between rows and an average of about 12 plants per meter. Each plot is four meters in length, and three replicates per treatment are used. Four weeks after planting, when the cotton plants have reached the two- to three-leaf stage, the plants are sprayed with a 50:50 acetone/wa-ter-mixture containing 0;25% of a nonionic, modified phthalic glycerol alkyl resin, emulsifier-spreader, and a sufficient amount of test compound to provide 0.0 (untreated control), 0.062, 0.125, or 0.25 kg/ha of test compound. About seven weeks after planting, when the cotton plants have reached the stage of first flowering, different plots (previously untreated), but in the same field, are sprayed with solutions of test compound prepared as described above. All plants are then permitted to grow to maturity using normal cultural practices. During the second week of October, the cotton from each plot is hand harvested, and the weight of the seed cotton determined for each plot. The results obtained from all treatments are reported in Tables X and XI below as the average weight in kg/ha of seed cotton obtained from the three replicates of each treatment. TABLE X EVALUATION OF l-NITRO-3-(a, a,a, 4-TETRAFLUORO-m TOLYL)GUANIDINE FOR YIELD ENHANCEMENT OF COTTON Average Yield Time of Rate of Seed Cotton Application kg/ha (kg)/Plot 2-3 leaf 0.0 (control) 1.57 0.062 1.72 2-3 leaf 0.0 (control) 1.70 0.125 1.85 2-3 leaf 0.0 (control) 1.97 0.25 2.22 First flowering 0.0 (control) 1.73 0.062 2.25 First flowering 0.0 (control) 1.61 0.125 2.20 First flowering 0.0 (control) 1.85 0.25 2.45 EXAMPLE 15 Evaluation of test compounds to determine their efficacy for increasing the number of U. S. No. 1 potatoes and the total weight of potatoes produced per plant In this evaluation, white potatoes (Solanum tuberosum Superior) (2016 kg/ha) are planted during the first week of April. Approximately five weeks after planting, when more than 80% of the potato plants have emerged, plots comprising two 9.6 meter rows, spaced 0.9 meters apart, are sprayed with a 50:50 acetone/water mixture containing 0.25% by weight of a modified phthalic glycerol alkyl resin, nonionic emulsifier-spreader, and sufficient test compound to provide 0.0 (untreated control), 0.25, 0.50, or 1.0 kg/ha of test compound. Six replicates per treatment are used. At one-week intervals, additional plots are sprayed in the same manner and at the same rates as described above. The treated plants are cared for in accordance with normal cultural practices utilized in the growing of potatoes. When said plants reach maturity, about 20 weeks after planting,. they are harvested. The total number of U. S. No. 1 potatoes per plot and total weight of all potatoes per plot are determined. Data obtained are reported in Tables XI and XII below. TABLE XI EVALUATION OF TEST COMPOUNDS FOR INCREASING THE NUMBER OF U. S. NO. 1 POTATOES PER PLANT USING WHITE POTATOES (SOLANUM TUBEROSUM CV. SUPERIOR) Rate % (#) Untreated Control of U. S. No. 1 Potatoes Compound kg/ha E1 E2 E3 1-Nitro-3-(&alpha;,&alpha;,&alpha;-4-tetrafluoro 1.0 +21 +27 +15 m-tolyl) guanidine 0.50 +23 +28 +14 0.25 +21 +30 +19 1-(3-Chloro-4-fluorophenyl) - 1,0 +19 +24 +19 3-nitroguanidine 0.50 +25 +20 + 7 0.25 +21 +24 +14 1-(m-methoxybenzyl)-3- 1.0 +10 +36 +19 nitroguanidine 0.50 +18 +32 +20 0.25 +23 +34 +18 1-(3,5-Dichlorophenyl-3- 1.0 +12 +38 +13 nitroguanidine 0.50 +14 +35 + 8 0.25 +15 +34 +10 E1, E2, E3 = Application of test compound one, two, or three weeks after plant emergence of the potato plants. (#) = Increase or decrease over untreated controls. TABLE XII EVALUATION OF TEST COMPOUNDS FOR INCREASING THE TOTAL WEICHT OF POTATOES (SOLANUM TUBEROSUM SUPERIOR) [WHITE POTATOES] COMPARED TO UNTREATED CONTROLS YIELDING 188 POUND/PLOT (380 CWT/ACRE, 42.6 METRIC TONS/HA) OF SAID POTATOES Total Potato Yield Per Treatment Rate % (#) Untreated Control Compound kg/ha E1 E2 E3 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4-tetrafluoro- 1.0 +17 +23 +13 m-tolyl) nitroguanidine 0.50 +19 +24 +12 0.25 +18 +26 +16 1-(3-Chloro-4-fluorophenyl)- 1,0 +15 +20 +17 3-nitroguanidine 0.50 +21 +16 + 5 0.25 +18 +20 +11 1-(m=Methoxyhenzyl)- 1.0 + 7 +35 +16 3-nitroguanidine 0.50 +15 +38 +17 0.25 +20 +30 +14 1-(3,5-Dichlorophenyl)- 1.0 +11 +32 +11 3-nitroguanidine 0.50 +12 +30 + 6 0.25 + 9 +28 + 7 E1, E2, and E3 indicate the time of application of test compound one, two, or three weeks, resectively, after emergence of the potato plants. (#) = Increase or decrease over untreated controls. EXAMPLE 16 Evaluation of test compounds to determine their efficacy for increasing the total weight of potatoes produced The procedure of Example 15 is repeated except that a variety of compounds is evaluated. The compounds are applied two weeks after the seedling plants have emerged, at application rates from 0.25 kg/ha to 2.0 kg/ha. The potatoes are harvested about 20 weeks after planting, and data obtained are reported in Table XIII below where the total fresh weight of potatoes from treated plots is compared with the total fresh weight of potatoes obtained from untreated plots. The same procedure as described above is employed except that the test compounds are prepared as a 30% liquid flowable formulation which is dispersed in water and applied as an aqueous spray. Data obtained with these flowable formulations is reported in Table XIII-A. The flowable concentrates used in this evaluation comprise: Percent W/W Test compound (90% pure) 30.00 Colloidal magnesium aluminum silicate 0.40 Sodium salts of polymerized alkyl naphthalene sulfonic acids 1.50 Propylene glycol/dipropylene glycol 8.00 Ethoxylated octylphenol 0.10 Nonylphenoxy polyethoxyethanol 0.10 Citric acid 0.07 Xanthan gum 0.06 Paraformaldehyde 0.10 Tap water 59.67 100.00 TABLE XIII EVALUATION OF TEST COMPOUNDS TO DETERMINE THEIR EFFICACY FOR INCREASING THE TOTAL WEIGHT OF POTATOES PRODUCED Total Tuber Fresh Rate Weight Percent (+) Treatment kg/ha Untreated Controls Untreated controls = 151 cwt/A* l-Benzyl-3-nitroguanidine 2.0 +12 0.5 +13 l-Nitro-3-(: a,a-trifluoro- m-tolyl)guanidine 0.5 + 9 l-(m-acetylphenyl)-3- 1.0 +18 nitroguanidine 0.25 + 6 l-(m-Methoxyphenethyl)- 2.0 + 5 3-nitroguanidine 0.5 +10 1- (4-Chloro-m-tolyl) - 3-nitroguanidine 0.5 + 4 l-(m-Methoxyphenyl) - 3-nitroguanidine 0.5 + 3 l-(m-Fluorobenzyl)3-nitroguanidine 2.0 + 6 l-(m-Bromophenyl)- 2.0 + 2 3-nitroguanidine 0.5 +17 1-Nitro-3-(3,4-xylyl)guanidine 0.5 + 3 l-[m-(Difluoromethoxy)- 2.0 + 2 phenyl]-3-nitroguanidine 0.5 +20 l-Nitro-3-(m-propoxybenzyl)guanidine 2.0 +25 l-(a-Methylbenzyl)- 2.0 + 9 3-nitroguanidine 0.5 +16 * Cwt/A 2 Hundred weight per acre TABLE XIII-A EVALUATION OF TEST COMPOUNDS FORMULATED AS FLOWABLE CONCENTRATES TO DETERMINE THEIR EFFICACY FOR INCREASING THE TOTAL WEIGHT OF POTATOES PRODUCED Total Tuber Fresh Rate Weight Percent Ct) Treatment kg/ha Untreated Controls 1-Nitro-3-(a,a,a-tri- 0.5 +11 fluoro-m-tolyl)guanidine 0.25 +11 0.125 +11 l-(3,5-Dichlorophenyl)- 0.5 + 8 3-nitroguanidine 0.25 + 8 0.125 +11 l-Nitro-3-(a,a,a,4- 0.5 + 8 tetrafluoro-m-tolyl)- 0.25 + 8 guan id ine 0.125 + 4 l-(m-Methoxybenzyl)- 0.5 + 6 3-nitroguanidine 0.25 +13 0.125 + 5 Untreated control average total yield 202 cwt/A. EXAMPLE 17 Evaluation of test compounds to determine their efficacy for increasing the total weight of Kennebec variety potatoes produced The procedure of Example 15 is again repeated except that Kennebec variety potatoes are used for the evaluations. Test compounds are applied as aqueous/ acetone mixtures per Example 15 but at rates sufficient to provide from 0.5 kg/ha to 2.0 kg/ha. The potatoes are harvested at maturity, about 20 weeks after planting, and data obtained are reported in Table XIV. Data are reported as total fresh weight of potatoes compared with the total fresh weight of potatoes obtained from untreated controls. TABLE XIV EVALUATION OF TEST COMPOUNDS TO DETERMINE THEIR EFFICACY FOR INCREASING THE TOTAL WEIGHT OF KENNEBEC VARIETY POTATOES Total Tuber Fresh Rate Weight Percent (+) Treatment kg/ha Untreated Controls 1-Cyano-3-(a,a,a-tri- 2.0 +14 fluoro-m-tolyl)guanidine 0.5 + 7 l-Benzyl-3-cyanoguanidine 0.5 +16 l-(m-Chlorophenyl)-3nitroguanidine 2.0 + 9 l-Nitro-3-(3,5-xylyl) guanid ine 2.0 + 9 l-(m-Methoxybenzyl)-3- 2.0 +15 nitroguanidine 0.5 + 6 l-(m-Methylbenzyl)3- nitroguanidine 2.0 + 6 l-Cyano-3-(m-Methoxybenzyl)guanidine 2.0 + 5 l-(p-Fluorobenzyl)-3- 2.0 + 8 nitroguanidine 0.5 + 4 EXAMPLE 18 Evaluation of test compounds for increasing total potato yield and increasing production of U. S. No. 1 potatoes on different potato varieties The procedure of Example 15 is employed with the following exceptions: (1) test compounds are applied at two rates, 0.25 and'l.0 kg/ha, (2) several different varieties of white potatoes (Solanum tuberosum) are used, and (3) the compounds are applied one or two weeks after the potato plants have emerged from the soil. The several varieties of potatoes employed in this evaluation are Katahdin, Kennebec, Norchip, and Superior. Data obtained are reported in Table XV below. TABLE XV EVALUATION OF TEST COMPOUNDS FOR INCREASING THE TOTAL WEIGHT OF POTATOES AND THE NUMBER OF U.S. NO. 1 POTATOES PRODUCED PER PLANT VARIETY KATAHDIN Tuber Fresh Weight % (#) Untreated Controls Rate E 1 E 2 Compound kg/ha U. S. No. 1 Total U. S. No. 1 Total 1-Nitro-3-(a,a,a,4-tetra- 1.0 +13 +14 +12 +15 fluoro-m-tolyl) guanidine 0.25 +13 +12 +15 +18 1-(m-Methoxybenzyl)-3- 1.0 +21 +21 +11 +13 nitroguanidine 0.25 +18 +18 + 4 + 6 Untreated controls : Average yield - 207 cwt/A, U.S. No. 1; 232 cw/A total. E 1 = Test compound applied one week after emergence of potato plants. E 2 = Test compound applied two weeks after emergenceof potato plants. Cwt/A = Hundred weight per acre. (#) = Increase or decrease over untreated controls. TABLE XV (Continued) VARIETY NORCHIP Tuber Fresh Weight % (#) Untreated Controls Rate E1 E 2 Compound kg/ha U. S. No. 1 Total U. S. No. 1 Total 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4-tetra- 1.0 -11 -8 +16 +17 fluoro-m-tolyl) nitro- 0.25 + 6 +5 + 9 +10 guanidine 1.0 - 3 -2 + 3 + 4 1-(m-Methoxybenzyl)-3- 0.25 0 +1 + 4 + 6 nitroguanidine Untreated controls : Average yield - 257 cwt/A, U. S. No. 1 ; 307 cwt/A total. (#) = Increase or decrease over untreated controls. TABLE XV (Continued) VARIETY NORCHIP Tuber Fresh Weight % (#) Untreated Controls Rate E1 E 2 Compound kg/ha U. S. No. 1 Total U. S. No. 1 Total 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4-tetra- 1.0 +12 +11 +1 +4 fluoro-m-tolyl) guanidine 0.25 + 7 + 7 +7 +7 1-(m-Methoxybenzyl)-3- 1.0 + 7 + 7 +3 +5 nitroguanidine 0.25 +10 +10 +4 +3 Untreated controls : Average yield - 302 cwt/A, U. S. No. 1 ; 368 cwt/A total. (#) = Increase or decrease over untreated controls. TABLE XV (Continued) VARIETY SUPERIOR Tuber Fresh Weight % (#) Untreated Controls Rate E1 E 2 Compound kg/ha U. S. No. 1 Total U. S. No. 1 Total 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4-tetra- 1.0 +16 +14 +19 +19 fluoro-m-tolyl) guanidine 0.25 +14 +14 +22 +21 1-(m-Methoxybenzyl)-3- 1.0 +14 +13 +16 +14 nitroguanidine 0.25 +17 +15 +27 +22 Untreated controls : Average yield 283 cwt/A, U. S. No. 1 ; 322 cwt/A total. (#) = Increase or decrease over untreated controls. EXAMPLE 19 Evaluation of test compounds for increasing total fresh weight of potatoes (Solanum tuberosum Superior) The procedure of Example 15 is repeated except that a variety of compounds is evaluated at rates of from 0.125 kg/ha to 1.0 kg/ha, and the 50/50 aqueous/acetone mixture containing 0.25% of the nonionic surfactant and the test compound is applied to the potato plants three weeks after they have emerged from the soil. The potatoes are harvested about 20 weeks after planting, and the total weight of potatoes from treated plants is compared to the total weight of potatoes from the untreated controls. Data obtained are reported in Table XVI below. TABLE XVI EVALUATION OF TEST COMPOUNDS APPLIED THREE WEEKS AFTER EMERGENCE OF THE POTATO PLANTS (VARIETY SUPERIOR) Rate Total Tuber Fresh Weight Compound kg/ha % (t) Untreated Controls l-Benzyl-3- 1.0 + 9 nitroguanidine 0.5 + 8 0.25 + 5 0.125 + 2 Untreated controls average total yield: 402 cwt/A 1-Nitro-3-(a,a,a- 1.0 +11 trifluoro-m-tolyl)- 0.5 +15 guanidine 0.25 + 9 0.125 + 1 Untreated controls average total yield: 389 cwt/A l-Cyano-3-(a,a,a- 1.0 + 7 trifluoro-m-tolyl)- 0.5 + 2 guanidine 0.25 - 5 0.125 - 4 Untreated controls average total yield: 398 cwt/A l-(m-chlorophenyl)- 1.0 +10 3-nitroguanidine 0.5 + 6 0.25 + 3 0.125 + 7 Untreated controls average total yield: 392 cwt/A (+) = Increase or decrease over untreated controls. TABLE XVI (Continued) Rate Total Tuber Fresh Weight Compound kg/ha % (+) Untreated Controls 1-(4-Chloro-a,a,a- 1.0 +10 trifluoro-m-tolyl)- 0.5 + 5 3-nitroguanidine 0.25 + 8 0.125 + 4 Untreated controls average total yield: 391 cwt/A 1-(4-Bromo-m-tolyl)- 1.0 + 2 3-nitroguanidine 0.5 + 4 0.25 + 4 0.125 + 6 Untreated controls-a-verage total yield: 410 cwt/A l-(3-Chloro-4- 1.0 + 8 fluorophenyl)-3- 0.5 + 6 nitroguanidine 0.25 + 5 0.125 0 Untreated controls average total yield: 412 cwt/A Cwt/A = Hundred Weight/Acre. (+) = Increase or decrease over untreated controls. EXAMPLE 20 Evaluation of test compounds for increasing the total potato yield and the number of U. S. No. 1 potatoes per plant using white potatoes (Solanum tuberosum Superior) The procedures of Example 15 is repeated except that test compounds are applied at rates of from 0.0625 kg/ha to 1.0 kg/ha three weeks after planting, two weeks pre-emergence or three weeks post-emergence. The test compounds are applied- li-n 50/50 aqueous/acetone mixture-containing 0.25% of the nonionic surfactant and sufficient test compound to provide from 0.0625 kg/ha to 1.0 kg/ha. The potatoes are harvested when they reach maturity, about 20 weeks after planting. Data obtained are reported in Table XVII below. TABLE XVII EVALUATIONOF TEST COMPOUND FOR INCREASING. THE TOTAL WEIGHT OF POTATOES AND THE NUMBER OF U.S. NO. 1 POTATOES PRODUCED PER PLANT WHEN THE TEST COMPOUND IS APPLIED THREE WEEKS POST PLANTING - TWO WEEKS PRE-EMERGENCE Rate Tuber Fresh Weight % #) Untreated Controls Compound kg/ha U. S. No. 1 Total 1-(3-5-Dichlorophenyl)-3-nitroguanidine 1.0 +13 +14 0.5 + 7 + 8 0.25 + 4 + 7 Untreated controls average yield ; 0.125 + 1 + 3 364 cwt/A U.S. No. 1, 394 cwt/A total 0.0625 + 9 +11 1-Nitro-3-(&alpha;,&alpha;,&alpha;,-4-tetrafluoro-m- 1.0 +13 + 4 tolyl) guanidine 0.5 + 5 + 4 0.25 + 1 + 1 Untreated controls average yield : 0.125 + 2 + 4 382 cwt/A U.S. No. 1, 412 cwt/A total 0.0625 + 5 + 5 1-(m-Methoxybenzyl)-3-nitroguanidine 1.0 +10 +11 0.5 + 6 + 6 0.25 + 4 + 5 Untreated controls average yield : 0.125 + 4 + 5 362 cwt/A U.S. No. 1, 394 cwt/A total 0.0625 + 4 + 5 (#) = Increase or decrease over untreated controls. TABLE XVII (Continued) Rate Tuber Fresh Weight % #) Untreated Controls Compound kg/ha U. S. No. 1 Total 1-(3,5-Dichlorophenyl(-3-nitro- 1.0 +11 + 7 guanidine 0.5 +19 +18 0.25 +10 +12 Untreated controls average yield : 0.125 +12 +10 364 cwt/A U.S. No. 1, 394 cwt/A total 0.0625 +19 +18 1-Nitro-3-(&alpha;&alpha;&alpha;,4-tetrafluoro-m- 1.0 +16 +12 tolyl) guanidine 0.5 +17 +17 0.25 +11 +12 Untreated controls average yield : 0.125 + 4 + 4 382 cwt/A U.S. No. 1, 412 cwt/A total 0.0625 +14 +13 1-(m-Methoxybenzyl)-3-nitro- 1.0 + 5 + 3 guanidine 0.5 +10 + 9 0.5 + 8 + 8 Untreated controls average yield : 0.125 + 9 + 8 331 cwt/A U.S. No. 1,366 cwt/A total 0.0625 + 7 + 7 (#) = Increase or devrease over untreated controls. EXAMPLE 21 Evaluation of test compounds formulated as emulsifiable concentrates or aqueous dispersions to determine their efficacy for increasing the number of U.S. No. 1 potatoes and the total weight of potatoes produced per plant. In this evaluation, white potatoes, variety Superior, are planted during mid-April. Three weeks after the plants have emerged; plots, comprising two 9.6 meter rows, spaced 0.9 meters apart, are sprayed with an aqueous dispersion of one of the following formulations: 1) Compound Percent W/V l-(3,5-Dichlorophenyl)-3-nitroguanidine . 11.0 N-Methyl pyrrol idone 38.0 Tenneco 500/100 aromatic solvent 35.0 Anionic-nonionic surfactant T-Mulz 339 emulsifier 6.0 Multifilm X-77 spreader-activator 10.0 100.0 Tenneco 500/100 aromatic solvent is a product of Tenneco Oil Company, Houston, Texas; having the following characteristics: Specific gravity 15.56/15.560C 0.860-0.875 Acidity No free acid Flash, TCC min. oF 100 Kouri-Butanol value - min. 92 Aromatics, Vol. % - min. 95 Distillation range temp. Not below 2900F Multifilm X-77 is a product of Colloidal Products Corporation, Sausalito, California; having the following characteristics: Specific gravity 20/200C 0.98 Density lb./gal. at 200C 8.20 Surface tension, Dynes/cm at 200C 31 T-Mulz 339 is a product of the Thompson-Hayward Chemical Company, Kansas City, Kansas, and is a blend of anionic-nonionic emulsifying agents. 2) Compound Percent W/V l-Nitro-3-(a, a, a,4-tetrafluoro m-tolyl)guanidine 11.0 NaOH 2.3 H20 86.7 100.0 3) Compound Percent W/V l-(m-Methoxybenzyl)-3-nitroguanidine 11.0 N-Methylpyrrolidone 57.0 Cg-C10 alcohol 24.0 Emulphor EL 620 8.0 100.0 Emulphor EL 620 is a polyoxyethylated vegetable oil marketed by GAF Corporation, New York, N. Y. The treated plants are cared for in accordance with normal cultural practices utilized in the growing of potatoes until they reach maturity. When said plants reach maturity, about 20 weeks after planting, they are harvested. The total number of U. S. No. I potatoes per plot and total weight of all potatoes per plot are determined. Data obtained are reported in Table XVI II below. TABLE XVIII EVALUATION OF FORMULATED TEST COMPOUNDS TO DETERMINE THEIR EFFECTIVENESS FOR INCREASING PRODUCTION OF U.S. NO. 1 POTATOES AND TOTAL WEIGHT OF POTATOES PRODUCED PER PLANT PERCENT INCREASE OR DECREASE OVER UNTREATED CONTROLS POTATOES RATE KG/HA FORMULATION PER PLANT 0.5 0.25 0.125 0.0625 &num; 1 1-(3,5-Dichlorophenyl-3- U.S. No. 1 + 4 + 5 + 6 + 6 nitroguanidine Total + 4 + 5 + 6 + 6 &num; 2 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4-tetra- U.S. No. 1 + 6 + 2 0 + 6 fluoro-m-tolyl) guanidine Total + 8 + 3 0 + 6 &num; 3 1-(m-Methoxybenzyl)-3- U.S. No. 1 +11 +16 + 7 + 9 nitroguanidine Total +11 +17 + 7 +10 Untreated controls - U.S. No. 1 = 360 cwt/A ; Total = 390 cwt/A. EXAMPLE 22 Evaluation of formulated test compounds for increasing the total weight of potatoes produced per plant (Variety Russett-Burbank) Following the procedure of Example 21, except that the evaluations are conducted in the north-western United States using white potatoes, Variety - Russett Burbank, the formulations &num;2 and &num;3 described in Example 21 are evaluated. Data obtained are reported in Table XIX below. TABLE XIX EVALUATION OF FORMULATED TEST COMPOUNDS FOR INCREASING THE TOTAL WEIGHT OF POTATOES PER PLANT (VARIETY - RUSSETT-BURBANK) PERCENT INCREASE OR DECREASE OVER UNTREATED CONTROLS WEEK OF POST RATE KG/HA FORMULATION APPLICATION 0.5 0.25 0.125 0.0625 &num; 2 1-Nitro-3-(&alpha;, &alpha;, &alpha;,4-tetra- 1 - 3 0 +14 + 6 fluoro-m-tolyl) guanidine 2 + 8 +10 + 9 +11 &num; 3 1-(m-Methoxybenzyl)-3- 1 - 1 -2 + 2 +11 nitroguanidine 2 + 6 +14 + 4 + 2 Untreated controls = U.S. No. 1 = 465 cwt/A, Total = 494 cwt/A. EXAMPLE 23 Evaluation of test compounds for increasing total potato yield and increasing production of U. S. No. 1 potatoes The following evaluations are conducted to evaluate a variety of test compounds as plant growth regulants effective for increasing the total weight of potatoes produced by potato plants and also for increasing the production of U. S. No. 1 potatoes produced by said plants. In these tests, potato plants, Superior variety, are grown in tubs in the greenhouse. The tubs, 2 ft. x 1 ft. x 1 ft., each contain two plants, and two tubs per treatment are--us¯ed¯¯for evaluation. Two weekspost-emergence the plants are sprayed with an aqueousacetone (50/50) mixture containing 0.25% of a nonionic wetting agent (nonylphenol containing 9 mols of ethylene oxide, oleic acid, and isopropanol) and sufficient test compound to provide 1 kg/ha of test compound. The plants are grown to maturity and harvested. Results obtained are reported in Table XX below. TABLE XX EVALUATION OF TEST COMPOUNDS FOR INCREASING TOTAL POTATO YIELD AND INCREASING PRODUCTION OF U.S. NO. 1 POTATOES Total Tuber Total U.S. No. 1 Fresh Weight Tuber Fresh Weight Treatment Percent (t) Untreated Controls l-(m-Cyanophenyl)-3nitroguanidine + 4 Methyl m-(3-nitroguanidine)benzoate + 5 +14 l-(m-Ethoxyphenyl)3-nitroguanidine + 1 + 8 1-(4-Fluoro-m-tolyl)3-nitroguanidine + 3 l-[m-(Difluoromethoxy) phenyl] -3-nitroguanidine +31 l-Nitro-3-[m-(2, 2, 2-tri- fluoro-l,l-dihydroxyethyl) phenyl]guanidine +9 l-(2-Fluoro-5-methylbenzyl)- 3-nitroguanidine +17 +30 1- (2-Fluoro-5-methoxy- benzyl)-3-nitroguanidine + 9 +26 l-(2-Fluoro-3-methylbenzyl)-3-nitroguanidine +13 +22 l-Nitro-3-[m-(trifluoromethoxy)phenyl]guanidine + 7 +13 Untreated control average total yield: 337 Cwt/A. EXAMPLE 24 Evaluation of test compounds for increasing sugar yield from sugar beets In the following tests, sugar beets (Beta vulgaris, L.) are planted during the third week of March in field plots. The plants are cared for in accordance with normal practices employed in the raising of sugar beet crops, except that evaluation plots are sprayed, either 120 days or 60days prior to harvest, with aqueous dispersions of test compound formulated as emulsifiable concentrates. When the plants reach maturity, the beets are harvested, and the sugar yield and raw juice purity -- determined for all treatments. The formulated compositions evaluated in these tests are as follows: Compound Percent W/V 1) l-Nitro-3-(a, a, a,4-tetrafluoro- m- tolyl) guanidine 11.0 N-Methylpyrrolidine 38.0 Substituted benzenes (aromatic solvent) 35.0 Alkylarylpolyoxyethylene glycol, fatty acid and propanol 10.0 Octylphenoxy polyethoxy ethanol (nonionic-surfactant) 6.0 100.0 Compound Percent W/V 2) l-(m-Methoxybenzyl)-3-nitroguanidine 11.0 N-Methylpyrrolidone 38.0 Alkylarylpolyoxyethylene glycol fatty acid and propanol 10.0 Substituted benzenes (aromatic solvent) 35.0 Octylphenoxy polyethoxy ethanol (nonionic-surfactant) 6.0 100.0 Data obtained are reported in Tables XXI and XXII below. In these evaluations, test compounds were found to be effective on sugar beets for increasing recoverable sugar yields. For example, the compound l-(m-methoxybenzyl)-3-nitroguanidine applied at 1.0-0.25 lb/A 60 days before harvest gave 611 lbs/A more recoverable sugar than the untreated controls which yielded 6,130 Ibs/A of sugar. TABLE XXI EVALUATION OF TEST COMPOUNDS APPLIED 12O DAYS BEFORE HARVEST FOR INCREASING SUGAR YIELD FROM SUGAR BEETS (BETA VULGARIS, L.) RATE PERCENT INCREASE OVER UNTREATED CONTROLS FORMULATION KG/HA PERCENT RAW JUICE RECOVERABLE 1) SUGAR PERCENT PURITY SUGAR 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4-tetrafluoro- 1.0 + 5 0 + 1 m-tolyl) guanidine 0.25 + 4 + 1 + 6 0.0625 + 5 + 1 + 4 2) 1-(m-Methoxybenzyl0-3- 1.0 + 3 0 + 7 nitroguanidine 0.25 + 3 + 1 + 4 0.0625 + 4 0 + 5 Untreated controls - 14.49 90.25 18.37 (6,130 1bs/A) TABLE XXII EVALUATION OF TEST COMPOUNDS APPLIED 6O DAYS BEFORE HARVEST FOR INCREASING SUGAR YIELD FROM SUGAR BEETS (BETA VULGARIS, L.) PERCENT INCREASE OVER UNTREATED CONTROLS RATE PERCENT RAW JUICE RECOVERABLE FORMULATION KG/HA SUGAR PERCENT PURITY SUGAR 1) 1-Nitro-3-(&alpha;,&alpha;,&alpha; ;,4-tetrafluoro- 1.0 + 2 + 1 + 8 m-tolyl) guanidine 0.25 + 2 + 1 + 2 0.625 + 2 + 1 + 4 2) 1-(m-Methoxybenzyl)-3- 1.0 + 3 + 1 +10 nitroguanidine 0.25 + 1 0 +10 0.625 + 1 0 + 3 Untreated controls - 14.62 90.17 18.22 (6,183 1bs/A) EXAMPLE 25 Evaluation of test compounds as yield-enhancing agents for garlic (Allium sativum cv Balady) In this evaluation, garlic bulbs are planted in the field at a seeding rate of 475 kg/ha. Test plots include two ridges, 0.6 meters wide and 10 meters in length. Thirty-one days after planting, the seedling plants are sprayed with an aqueous suspension of test compound which provides from 0.063 to 0.5 kg/ha of compound being evaluated. The aqueous suspension is prepared by dispersing an emulsifiable concentrate containing the test compound in water. The emulsifiable concentrate has the following composition: Compound Percent W/W Nitroguanidine test compound 11.0 N-Methylpyrrolidone 38.0 Tenneco 500/100 aromatic solvent 35.0 Anionic-nonionic surfactant T-Mulz 339 emulsifier 6.0 Multifilm X-77 spreader-activator 10.0 100.0 Six months after planting, the garlic is harvested, and the results obtained are reported in Table XXIII below. TABLE XXII I EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR GARLIC Fresh Weight of Bulbs Compound kg/ha % (+) Untreated Control l-(3,5-Dichlorophenyl)- 0.5 + 8 3-nitroguanidine 0.125 + 5 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4- 0.125 +13 tetrafluoro-m-tolyl)- 0.063 + 4 guanid ine l-(m-Methoxybenzyl)- 0.5 + 9 3-nitroguanidine 0.125 + 8 Untreated control average yield: 17.3m Ton/ha EXAMPLE 26 Evaluation of test compounds as yield-enhancing agents for carrots (Daucus carota cv chantenay) In this evaluation, carrots are planted in fields at a seeding rate of 9 kgfhectare. Forty-six days after planting, the seedling plants are sprayed with aqueousacetone (50/50) dispersion containing test compound and 0.25% of Multifilm X-77 spreader-activator. Plots used for evaluation include two ridges 0.6 meters wide and 10 meters in length. About four months after planting, the carrots are harvested, and the results obtained reported in Table XXIV below. TABLE XXIV EVALUATION OF NITROGUANIDINE TEST COMPOUNDS AS YIELD-ENHANCINr AGENTS FOR CARROTS Rate Fresh Weight of Roots Compound kg/ha % (+) Untreated Control 1-(3,5-Dichlorophenyl)- 0.5 + 1 3-nitroguanidine 0.125 + 6 l-Nitro-3-(a,a,a,4- 0.125 tetrafluoro-m-tolyl)- 0.063 +26 guanidine l-(m-Methoxybenzyl)- 0.5 +20 3-nitroguanidine 0.125 +19 Untreated control average yield 26.Om ton/ha EXAMPLE 27 Evaluation of test compounds as yield-enhancing agents for turnips (Brassica rapa cv white purple top globe) In this evaluation, test compound is dissolved in an acetone/water (50/50) mixture containing test compound and 0.25% of Multifilm X-77 spreader-activator. The test composition is applied post-emergently to the foliage of turnips eight or twelve weeks after planting. Plots used for evaluation are single rows, 10 feet long, arranged on 100 centimeter centers. Six replicates per treatment are used, and the turnips are harvested about four months after planting. Data obtained are reported in Table XXV below. TABLE XXV EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR TURNIPS Rate Fresh Weight of Roots Treatment kg/ha % (+) Untreated Controls l-(m-Methoxybenzyl)- 2.0 + 5 3-nitroguanidine 0.5 + 3 Applied eight weeks post planting (Root thickness 1.25-2.5 cm) l-(m-Methoxybenzyl)- 2.0 +29 3-nitroguanidine 0.5 + 5 Applied twelve weeks post planting (Root thickness 3.8-7.5 cm) Untreated control average yield: 332cwt/acre. EXAMPLE 28 Evaluation of test compounds as yield-enhancing agents for red table beets (Beta vulgaris cv green top bunching Following the procedure of Example 27 above, but substituting red table beets for turnips, demonstrates the yield-enhancing effects of the compounds of the invention on red table beets. Data obtained are reported in Table XXVI below. TABLE XXVI EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR RED TABLE BEETS Rate Fresh Weight of Roots Treatment kg/ha % (+) Untreated Controls l-(m-Methoxybenzyl) 2.0 +13 3-nitroguanidine 0.5 + 5 Applied eight weeks post planting (Plant height 7.5-15 cm) l-(m-Methoxybenzyl)- 2.0 +14 3-nitroguanidine 0.5 - 2 Applied 12 weeks post planting (Plant height 20-40 cm) EXAMPLE 29 Evaluation of test compounds as yield-enhancing agents for tulips [(Tulipa sylvestris cv Iverson (albino)] In this evaluation, field-grown tulips are treated when about 100% of the tulips are in bud or when all are in late bloom. The plants are sprayed with an aqueous/acetone mixture (20/80) containing test compound and 0.25% Multifilm X-77 spreader-activator. Plot sizes utilized in this evaluation are 1 row x 5 ft. long with each treatment replicated six times. Bulbs are harvested six weeks after the late bloom treatment. Data obtained are reported in Table XXVII below. TABLE XXVI I EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR TULIPS Large Bulbs Percent of Rate Fresh Weight Large Bulbs Treatment kg/ha % (+) Untreated Controls l-(m-Methoxybenzyl)- 2.0 +26 +35 3-nitroguanidine 0.5 +80 +81 (100% in bud) l-(m-Methoxybenzyl)- 2.0 0 + 5 3-nitroguanidine 0.5 +53 +49 (Full bloom) EXAMPLE 30 Evaluation of test compounds as yield-enhancing agents for sunflowers (Helianthus annus cv Dohlgren D0164) In this evaluation, sunflowers growing in 18 cm pots, spaced in rows 75 cm apart, are treated at the V8, Vll-12, V16, V20 (R1) or V22 (R2-5) stage of growth with aqueous dispersion of test compound. Test compounds are dispersed in acetone/water mixtures (2:1 ratio) containing 0.25% of a nonionic wetting agent (i.e., nonylphenol containing 9 moles of ethylene oxide, oleic acid, and isopropanol). The dispersions are applied as aqueous sprays in sufficient amounts to provide 0.31 kg/ha thereof to the test pots. Five months after planting, the seed heads are harvested, and the weight of seeds from each plant is determined. Data obtained are reported in Table XXVI II below. TABLE XXVIII EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR SUNFLOWERS Rate Fresh Weight of Seeds Treatment kg/ha(+) Untreated Controls 1(3, 5-Dichlorophenyl) - 3-nitroguanidine Applied at the following vegetative stages: V8 0.31 +17 Vll-12 0.31 +37 V16 0.31 +26 V20 (R1) 0.31 +29 V22 (R2-5) 0.31 + 5 EXAMPLE 31 Evaluation of test compounds as yield-enhancing agents for tobacco (Nicotiana tabacum cv Coker 319) In this evaluation, Coker 319 variety tobacco plants are grown in 22.5 cm plastic pots, one plant per pot. The pots are placed in rows 50 cm apart, and four to six replicates per treatment are used for evaluation. When the plants are 5, 45 or 115 centimeters in height, they are. sprayed with an aqueous dispersion of test compound previously formulated as a liquid flowable formulation. The liquid flowable formulation contains, on a percent w/w basis, 30% l-(3,5-dichlorophenyl)-3nitroguanidine, 0.4% colloidal magnesium aluminum silicate, 1.5% naphthalene formaldehyde condensate, 8% polyethylene glycol, 0.1% nonylphenol ethylene oxide condensate (9-11 moles ethylene oxide), 0.1% sodium lignosulfonate, 0.07% citric acid, 0.06% xanthan gum, 59.67% water and 0.10% paraformaldehyde. The liquid flowable formulation is diluted with water and 0.25 of the Multifilm X-77 spreader-activator (alkylarylpolyoxyethylene glycols, free fatty acids and isopropanol) in the spray tank. The dispersion is sprayed on the plants in sufficient amounts to provide 0.25 kg/ha of test compound. The plants are grown to maturity and then harvested. Data obtained are reported in Table XXIX below. It is also noted that treatment of the tobacco plants retards senescence of the lower tobacco leaves and permits harvesting of all leaves in a single cutting. TABLE XXIX EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR TOBACCO Rate Dry Weight 6f Leaves Treatment kg/ha % (+) Untreated Controls 1- (3, 5-Dichlorophenyl) - 3-nitroguanidine Applied at the following plant heights: 5 cm 0.25 +38 45 cm 0.25 +64 115 cm 0.25 +112 EXAMPLE 32 Evaluation of test compounds as yield-enhancing agents for onions (Allium cepa cv Italian Red) In this evaluation, onions (Italian Red variety) are field planted, one plant per 10 centimeters. Threat7 ment plots used for evaluation include two ridges 0.6 meters wide and 10 meters in length. Thirty-seven days after planting, test plots are sprayed with an aqueous dispersion of one of the following formulations: Percent W/W 1) 1-(3,5-Dichlorophenyl)-3-nitroguanidine 11 Tenneco 500/100 aromatic solvent 35 Anionic-nonionic surfactant T-Mulz 339 emulsifier 6 Multifilm X-77 spreader-activator 10 N-Methylpyrrolidone 38 100 2) l-(m-Methoxybenzyl)-3-nitroguanidine 11 Tenneco 500/100 aromatic solvent 35 Anionic-nonionic surfactant T-Mulz 339 emulsifier 6 Multifilm X-77 spreader-activator 10 N-M.ethylpyrrol idone 38 100 3) 1-Nitro-3-(a,a,a,4-tetrafluoro-m- tolyl)guanidine 11 Tenneco 500/100 aromatic solvent 35 Anionic-nonionic surfactant T-Mulz 339 emulsifier 6 Multifilm X-77 spreader-activator 10 Tetrahydrofuran 38 100 Four months after treatment, the onions are harvested and the results obtained are reported in Table XXX below. TABLE XXX EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR ONIONS Rate Fresh Weight Per Bulb Compound kg/ha % (#) Untreated Controls 1- (3, 5-Dichloro- phenyl)-3-nitro- 0.5 +32 guanidine 0.125 +22 l-Nitro-3- (a, a, a,4- tetrafluoro-m-tolyl) 0.125 +25 guanidine 0.063 +32 1- (m-Methoxybenzyl) - 0.5 +21 3-nitroguanidine 0.125 +23 Untreated control average yield: 177 grams/bulb. EXAMPLE 33 Evaluation of test compounds as yield-enhancing agents for rutabaga (Brassica napus, variety napobrassica) The test procedure employed for evaluation of test compounds as yield-enhancing agents for rutabagas is as follows: The rutabagas are planted in early May; two months thereafter they are sprayed with an aqueous suspension of test compounds formulated as liquid flowable formulations described in Example 31. The rutabagas are harvested about four months after planting, and the data are reported in Table XXXI below. TABLE XXXI EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR RUTABAGAS Rate Fresh Weight Per Tuber Compound kg/ha % (+) Untreated Controls l-Nitro-3-(a, a, a- trifluoro-m-tolyl)- 0.125 +54 guanidine 0.5 + 3 1- (3, 5-Dichloro- phenyl)-3-nitro- 0.125 +39 guanid ine 0.5 + 3 l-(m-Methoxybenzyl)- 0.125 +19 3-nitroguanidine 0.5 + 8 Untreated control average yield: 510g/tuber EXAMPLE 34 Evaluation of test compounds as yield-enhancing agents for alfalfa (Medicago sativa, cv Saranoc) In this evaluation, aqueous dispersions of test compounds are sprayed pre-emergently on 12.5 x 12.5 cm fiber pots planted with alfalfa seeds. Each pot contains four plants, and each treatment is replicated five times. The evaluation test compounds are dispersed in acetone/ water (50/50) mixtures with 0.25% w/w of a nonionic wetting agent (nonylphenol containing 9 mols of ethylene oxide, oleic acid, and isopropanol) added. Six weeks after spraying at the first bloom stage of growth, the alfalfa is clipped, and the number of alfalfa stems per pot is determined. Data obtained are reported in Table XXXII below. TABLE XXXI I EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR ALFALFA Rate Number of Stems Compound kg/ha Per Pot 1-(3,5-Dichloro- 0.06 11.8 phenyl)-3-nitro- 0.03 12.4 guanidine 0.015 14.4 0.0075 14.8 Untreated control - 11.2 EXAMPLE 35 Evaluation of test compounds as yield-enhancing agents for tomatoes (Lycopersicon esculentum) To evaluate test compounds as yield-enhancing agents for tomatoes, process tomatoes are planted in two-row beds with 45 centimeters between rows. Each plot consists of two rows, six meters in length, and plots are sprayed with aqueous dispersions of test compound when the plants reach first bloom. Compounds being evaluated are formulated as described in Example 32. Aqueous dispersions are applied in sufficient amount to provide about 1.0 kg/ha of test compound to the treated plots, and data are taken when the tomatoes begin to ripen. Data obtained are reported in Table XXXIII below. TABLE XXXI II EVALUATION OF TEST COMPOUNDS AS YIELD-ENHANCING AGENTS FOR TOMATOES Rate Kg.Tomatoes/Six Meter Compound kg/ha Row for Two-Row Beds Untreated control - 106.8 1- (m-Methoxybenzyl) - 3-nitroguanidine 1.0 113.8 EXAMPLE 36 Evaluation of test compounds for extending the shelf life of cut flowers, i.e., daffodils (Narcissus pseudonarcissus) Daffodils are picked with fully-opened flower buds on the morning of the experiment. Stems are re-cut to 30 cm lengths and, within one-half hour of harvest, flower stems are immersed to a depth of 10 cm in 2,000 ml of the treating solution. The treating solution contains the test compound at 100 ppm. It is prepared by dissolving 100 mg of 1-nitro-3-Ca,a,a,4-tetrafluoro-m- tolyl)guanidine in 100 ml acetone and bringing the volume to 2,000 ml with deionized water. Control solutions consist of 5% acetone in water and water alone. After immersion in the test solution for three minutes, 30 minutes, 90 minutes, 270 minutes, or 24 hours, three specimens, selected at random, are transferred to 450 ml deionized water in 0.5-liter, wide-mouth amber jars and held there until the experiment is terminated; three specimens remain in the treating solution for the duration of the test. Stems of control flowers are held in 5% acetone for 30 minutes and 24 hours (three specimens for each immersion time) before transferring to deionized water while three specimens remain in water for the duration of the experiment. Treatments are distributed randomly in the laboratory maintained at about 21 C-25 C. Normal daylight is supplemented with flourescent lighting to provide 12-hour periods of light and dark. Flowers are rated for decorative value two days and four days post-treatment. Each specimen is separately rated for appearance of perianth and corona according to the scale shown below wherein increasing numerical value indicates increasing senescence. An unweighted mean value representing the overall appearance of the flower is then assigned to the treatment. Decorative Numerical Acceptability Rating Description A. Perianth Acceptable 1 Fresh appearance, perianth smooth and flat, no visual evidence of senescence Acceptable 2 Slight curling at margin Acceptable 3 Slight wilting Acceptable 4 Marginal discoloration (browning) and increased wilt Unacceptable 5 Pigment loss (translucence) in less than half perianth Unacceptable 6 Pigment loss (translucence) in more than half perianth Unacceptable 7 Completely desiccated and/or brown. B. Corona Acceptable 1 Erect and firm Acceptable 2 Expanding and flattening Acceptable 3 Slight wilt, margin discolored (brown) Unacceptable 4 Less than half wilted and/or brown, desiccated Unacceptable 5 More than half wilted and/or brown, desiccated. TABLE XXX IV EXTENDED VASE LIFE OF DAFFODILS TREATED FOR VARIOUS LENGTHS OF TIME IN 100 PPM of 1-NITRO-3-(a ,4-TETRAFLUORO-m-TOLYL)GUANIDINE Flower Freshness At Indicated Immersion Time Post Treatment Treatment Time Two Days Four Days l-Nitro-3- 3 minutes 1.8 2.5 (a, a, a,4-tetra- 30 minutes 1.7 2.5 fluoro-m-tolyl)- 90 minutes 1.7 2.7 guanidine 270 minutes 1.3 2.2 " 24 hours 1.3 2.2 " Duration 1.5 2.7 Acetone Control 30 minutes 2.2 3.5 Acetone Control 24 hours 2.3 3.8 Water Control Duration 2.2 3.3 The test is continued after the flowers have lost fresh-flower decorative value in order to continue observations on the stems. (J. L. Stoddart in British Plant Growth Regulator Group, Monograph No. 8, page 1, in part defines senescence in plants as follows: "More precisely, in leaves, it relates to the loss of structural integrity and photosynthetic competence in the chloroplast.") Retention of chlorophyll in daffodil flower stem (or scape) treated with the subject compound after untreated stems are depleted of chlorophyll, i.e., have-turned yellow or brown, is indicative of delayed senescence. In this test, the flower stem is rated for color and general appearance at 17 days and 25 days post treatment. Flower stems (scapes) are rated individually for color and turgidity and assigned numerical ratings as shown in the following Table XXXV. Increasing numerical value denotes progressive loss of photosynthetic competence, depletion of chlorophyll, and loss of structural integrity; in sum, increasing senescence terminating in death. RATING SYSTEM SENESCENCE RATING OF DAFFODIL CUT FLOWER STEMS (SCAPES) Numerical Rating ¯ Predominant Color and Appearance 1 Green, turgid, i.e., little or no visual evidence of senescence 2 Gray-green, turgid, i.e., slight senescence 3 Yellow-green, turgid 4 Yellow, turgid 5 Yellow-brown, turgid, i.e., advanced senescence 6 Brown, erect, i.e., complete senescence 7 Brown, collapsed, death TABLE XXXV DELAYED SENESCENCE OF DAFFODIL CUT FLOWER STEMS (SCAPES) TREATED WITH 100 PPM of 1-NITRO-3-(&alpha;,&alpha;,&alpha; ;,4-TETRAFLUORO-m-TOLYL) GUANIDINE Stem Color and Appearance At Immersion Indicated Time Post Treatment Treatment Time 17 Days 25 Days l-Nitro-3- 3 minutes 1.3 1.3 (a,a,a,4-tetra- 30 minutes 1.0 2.0 fluoro-m-tolyl)- 90 minutes 1.3 4.0 guanidine 270 minutes Not Rated 1.0 24 hours 1.3 5.3 11 Duration 4.0 7.0 5% Acetone Control 30 minutes 4.7 7.0 5% Acetone Control 24 hours 5.7 7.0 Water Control Duration 5.3 7.0 EXAMPLE 37 Evaluation of test compounds as yield-enhancing agents for alfalfa The procedure of Example 34 is repeated except that l-(3,5-dichlorophenyl)-3-nitroguanidine is applied at rates of from 3.5 g/ha to 20 g/ha with the results of the tests reported as alfalfa dry weight (t) percent of control. Data are reported in Table XXXVI below. TABLE XXXV I EVALUATION OF TEST COMPOUNDS AS YIELD ENHANCING AGENTS FOR ALFALFA Alfalfa dry weight Compound (+) % of control Untreated control 1-(3,5-Dichlorophenyl)- 3-nitroguanidine 20 g/ha + 8.0 15 g/ha +20.0 7.5 g/ha +39.0 3.5 g/ha +25.0 EXAMPLE 38 Evaluation of test compounds as yield enhancing agents for apples In this evaluation test compounds are dispersed in 50/50 acetone/water mixtures in sufficient quantity to provide dispersions or solutions containing 0, 10, 100 or 1000 ppm of active ingredient and about 0.25% by volume of a nonionic wetting agent (nonylphenol containing 9 mols of ethylene oxide, oleic acid and isopropanol). Test dispersions are applied to apple (Malus sylvestris Mill. cv. Oregon Spur Delicious) trees in the spring at the time of peak bloom. All test solutions are sprayed to run off. Each treat ment utilizes two trees selected at random from a block of uniformly blossoming individuals. During the growing season, the orchard in which the experiment is conducted is sprayed with normal fungicides and insecticides. Treatments are consistent with recommended cultural practices. At the end of the season, fruit from each tree is harvested, weighed and the average weight of fruit per tree determined. The results are reported in Table XXXVI I below. TABLE XXXVI I EVALUATION OF TEST COMPOUNDS AS YIELD ENHANCING AGENTS FOR APPLES Rate Average yield tree Compound (ppm) (lb. of fruit) !-(3,5-Dichloro- 1000 57.5 phenyl)-3-nitro- 100 61.5 guanidie 10 62.3 Control 0 39.3 1 (m-Methoxybenzyl) - 1000 36.3 3-nitroguanidine 100 62.8 10 58.5 Control 0 47.5 EXAMPLE 39 Extended shelf life of swiss chard The deterioration of cut leaves of swiss chard is slowed following a brief dip of the leaves in a solution containing l-Cm-methoxybenzyl)-3-nitroguanidine in acetone to produce concentrations of test compound in the range of 8 to 512 ppm. Leaves are cut from field-grown swiss chard plants and each leaf is cut in half lengthwise, with one piece being dipped for 60 seconds in test solution and the second for 60 seconds in a solution of H20 and the appropriate control level of acetone (no separate acetone effect is observed). The leaf pieces are drained and then laid in trays with moist toweling. After four days at 200C, the trays are exposed to 300C for another four days. Senescence is monitored by visual observation of the loss of chlorophyll and/or progression of necrosis of the leaves. The effective concentration range is above 8 or 64 ppm. Treatment (ppm) Retardation of l-(m-methoxybenzyl-3- Senescence, % nitroguanidine of control 1 0 8 25 64 70 512 75 EXAMPLE 40 Extending vase life of cut gladiolus flowers by treating with substituted nitroguanidines The vase life of cut flowers is the length of time that the flower retains its decorative value. Vase life is, in part, determined by the cut stem's ability to continue to conduct nutrients and water to, and provide support for the flower. The ability is especially impor tant for flowers whose stems bear many florets, such as, for example, the gladiolus. When such flowers are cut with closed buds which eventually open while in the vase and when bud-opening is acropretally with time, maximum vase life is especially dependent upon a functioning stem. Gladiolus flowers are obtained from a local nursery distributor and transported to the laboratory wrapped and boxed as customary in the trade. Stems are recut to 30 cm lengths in a cold-room maintained at 40C and 60% rh and immersed in a solution, hereafter referred to as the treating solution of the following composition: Component Sucrose 20.00 Citric acid, monohydrate 4.20 8-Hydroxyquinoline citrate 0.20 Deionize-d water ca.900 ml Reaction adjusted to pH 4.6 with 10 molar solution of potassium hydroxide (about 3.9 mL/l of medium). Deionized water qs 1000 ml Jars are distributed at random around the laboratory which is maintained at 2100 to 250C. Normal daylight is supplemented with fluorescent lighting to provide 12 hour periods of light. Appropriate holding solution is replenished as needed. Flowers are rated for decorative value five days post-treatment. The overall appearance of all open florets on each of the five stems per replicate (two replicates per treatment) is assigned a single rating based on the scale shown below in which increasing numerical value indicates increasing senescence. The rating provides a single value which reflects the range of the severity of wilting or senescence shown by the individual florets on each stem. Freshness rating of cut gladiolus Flower: Severity of floret wilt and browning Decorative Numerical Acceptability Score Description Acceptable 1 Fresh, no wilt 1.5 Trace wilt (curl) &commat; margin 2 Slight wilt extending beyond margin 2.5 Moderate wilt with slight marginal browning Unacceptable 3 Pronounced wilt and browning 3.5 Severe wilt, browning with areas of desiccation 4 Complete wilt and desiccation An additional rating, based on the scale shown below, is assigned to reflect the extent of the wilting, i.e., the proportion of wilted florets. Freshness rating of cut gladiolus Flowers: Extent of wilting Decorative Proportion of Acceptability wilted florets % Acceptable 0 O - 10 10 - 25 25 - 50 Unacceptable 50 - 75 75 - 100 100 The numbers of open florets and healthy opening buds, i.e,, buds exposing at least 1 cm length of petal with no visible discoloration, step color and turgor, and bud color, are also recorded. Color changes accompanying senescence are shown in the rating system below. Freshness rating of cut gladiolus stem by color EMI108.1 <tb> <SEP> Increasing <tb> Rating <SEP> Color <SEP> Senescence <tb> Dk <SEP> gn <SEP> Dark <SEP> green <tb> Gn <SEP> Green <tb> YG <SEP> Yellow-green <tb> Y <SEP> Yellow <tb> Br <SEP> Brown <tb> The results of this experiment are shown below in Table XXXVIII. TABLE XXXVIII Extended vase life of cut gladiolus flowers treated with 100 ppm solutions of several substitution nitroquanidines Number of Floret wilt Open Opening Extent Stem Color of Treatment Florets Buds % Severity wilt Stem Bud Untreated (DIW) 19 5 50 - 75 3.0 sh/med Y6 Y6/Br Control (DIW) 25 9 10 - 25 2.5 slt YG/Gn YG/Gn Control (Ac) 21 11 10 - 25 2.5 slt YG/Gn Y6 1-Nitro-3-(&alpha;,&alpha;,&alpha; ;-tri- 23 42 0 1.0 nil Dk Gn Gn fluoro-m-tolyl) guanidine 1-(3,5-dichlorophenyl)- 49 15 0 1.0 nil Dk Gn Gn 3-nitroguanidine 1-Nitro-3-(&alpha;,&alpha;,&alpha;,4- 17 37 0 1.0 nil Dk Gn Gn tetrafluoro-m-tolyl)guanidine 1-(m-methoxybenzyl)-3- 42 21 0 1.0 mL Dk Gn Gn nitroguanidine AOAA 18 35 0 - 10 1.5 nil Dk Gn Gn It is seen that treating cut gladiolus flowers by immersing stems for 30 minutes in solutions of substituted nitroguanidines substantially extends the vase life of such flowers as compared to the vase life of flowers not so treated. The extension so obtained is based on several criteria including, increased number of acceptable open florets, increased number of healthy opening buds, reduction in both severity and extent of floret wilt, superior retention of green color in stems and buds, and superior retention of stem turgor. EXAMPLE 41 Delayed senescence in leafy green vegetables Kale and collard greens are bought at local farmers market and refrigerated in plastic bags until needed. The outermost leaves are discarded, and young, healthy, undamaged leaves are used for the experiment. Leaves are removed from the stalk by cutting with a sharp scalpel at the point of attachment. Immediately after removal, the petiole is inserted into the treating solutions contained in 4 ounce wide-mouth amber jars. In order to provide support for the leaf and to minimize loss of solution by evaporation, the jars are stoppered with plastic foam plugs which previously had a radial cut made with a scalpel to accommodate the leaf petiole. A treating solution with the experimental compound at 100 ppm is prepared by dissolving 200 mg of 1 nitro-3&num;a, cur, a,4-tetrafluoro-m-tolyl)guanidine in 100 ml acetone and bringing to a final volume of 2000 ml with deionized water. Treating solutions with the experimental compound at 10 ppm and 1 ppm are made by 10 fold serial dilution using 5% aqueous acetone as the diluent. Control solutions consisting of 5% aqueous acetone and water alone are included in the experiment. All treatments, with both kale and collard greens, are replicated four times, each replicate leaf deriving from a different plant. The jars are randomly distributed throughout the laboratory maintained at 2100 to 250C. Normal daylight is supplemented by fluorescent lighting to provide 12 hour periods of light and dark. The treating solutions are replenished as needed using a funnel with its stem inserted through the radial cut of the foam stopper. Leaves are rated for retention of green color at one, three and seven days after initiation of treatment. Color changes accompanying advancing senescence are shown in the rating system below. EMI111.1 <tb> Color <SEP> Increasing <tb> Code <SEP> Color <SEP> Senescence <tb> <SEP> 1 <SEP> Dark <SEP> Green <tb> <SEP> 2 <SEP> Green <tb> <SEP> 3 <SEP> Light <SEP> Green <tb> <SEP> 4 <SEP> Yellow.Green <tb> <SEP> 5 <SEP> Yellow <tb> <SEP> 6 <SEP> Brown <tb> The average ratings for the treatments on each of the observation days are shown in Table XL. TABLE XL RETENTION OF CHLOROPHYL AND DELAY OF SENESCENCE IN ISOLATED KALE AND COLLARD LEAVES TREATED WITH SOLUTIONS 1-NITRO-3- (a, a, a,4-TETRAFLUORO-M-TOLYL)GUANIDINE Concentration of l-nitro-3-(a,a,a,4-tetrafluoro-m- Leaf color after 1,3 and 7 tolyl)guanidine days after treatment PPM Kale Collard 1 3 7 1 3 7 100 1.0 1.0 1.8 1.0 1.1 2.8 10 1.0 1.0 1.0 1.0 1.0 3.5 1 1.0 1.0 2.0 1.0 1.3 3.7 0 (5% acetone) 1.0 1.0 5.3 1.0 2.3 4.5 0 (DIW) 1.0 2.0 5.3 .1.0 3.3 3.8 These results demonstrate the delay of onset and progress of senescence in treated leaves.

Claims: WHAT IS CLAIMED IS: 1. Guanidine compounds characterized by the following formulae: EMI113.1 wherein X1 is COCH3, halogen, CN, CH2CN, C(OH)2CF3, OCHF2, OCF3, CH3, SCH3, CF3, NO2, OCF2CHF2, OCH3, N(CH3)2, COOCH3 or CH20R3 where R3 is H or CH3; Y1 is H, halogen, CH3; Z1 is H, CH3, halogen, OCH3 or CF3; R is H or CH3; with the provisos that when X1 is CH3, OCH3, F, C1 or Br and R is H, then Y1 and Z1 cannot both be hydrogen; and when X1 is C1 and Z1 and R are each hydrogen, then Y1 cannot be methyl; and the salts or tautomers thereof; EMI113.2 wherein X2 is H, OH, straight or branched C1-C4 alkoxy, SCH3, halogen, OCF3, CF3, straight or branched C1-C4 alkyl EMI113.3 tetrahydro-2H-pyran-2-yl; Y2 is H or F; Z2 is F, H, CH3 or OCH3; W2 is H or F; m is an integer of 0, 1 or 2; R2 is H, CH3, 02H5 or CF3; with the provisos that when m is 0 and R2 is H or CH3, then W2, X2, Y2 and Z2 cannot all be hydrogen; and when m is 1, then R2, W2, X2, Y2 and Z2 cannot all be hydrogen; and the salts or tautomers thereof; EMI114.1 wherein X3 is OCH3, CH3, halogen or CF3; Y3 is H, OH or halogen and Z3 is H or C1; with the provisos that Y3 and Z3 can both be hydrogen only when X3 is OCH3; and when X3 and Y3 are each C1, Br or I, then Z3 cannot be hydrogen; and when X3 is CH3 and Z3 is H, then Y3 cannot be C1; and the salts or tautomers thereof; EMI114.2 wherein W4 is H or F and X4 is straight or branched C1-C4 alkoxy, straight or branched C1-C4 alkyl or F; with the provisos that when W4 is F, X4 is H; and the salts or tautomers thereof. 2. Guanidine compounds according to Claim 1, said compounds represented by formula, EMI114.3 wherein X1, Y1, Z1, and R are as described in Claim 1; and the salts or tautomers thereof. 3. Guanidine compounds according to Claim 1, said compounds represented by formula, EMI115.1 wherein W2, X2, Y2, Z2, R2, and m are as described in Claim 1; and the salts or tautomers thereof. 4. Guanidine compounds according to Claim 1, said compounds represented by formula, EMI115.2 wherein X3, Y3, and Z3 are as described in Claim 1; and the salts or tautomers thereof. 5. Guanidine compounds according to Claim 1, said compounds represented by formula, EMI115.3 wherein W4 and X4 are as described in Claim 1, and the salts or tautomers thereof. 6. Guanidine compounds according to Claim 2, wherein said compounds are l-nitro-3-Ca,a,a,4-tetrafluoro- m-tolyl) guanidine, 1-(3,5-dichlorophenyl)-3-nitro guanidine, l-nitro-(a,a,a-trifluoro-m-tolyl)guanidine, l-(m-acetylphenyl)-3-nitroguanidine, I-[m-(difluoromethoxy)phenyl]-3-nitroguanidine, or mixtures thereof. 7. Guanidine compounds according to Claim 3, wherein said compounds are l-(m-methoxybenzyl)-3-nitroguanidine, 1-(o-fluorobenzyl)-3-nitroguanidine, 1-(2fluoro-5-methoxybenzyl)-3-nitroguanidine, 1-(p fluorohenzyl)-3-nitroguanidine, or mixtures thereof. 8. A method for increasing crop yield of underground stem crops, underground stem ornamentals, root crops, graminaceous crops, forage crops, tomatoes, tobacco, sunflowers, cucurbits, cotton, and epigynous fruits, said method characterized by: applying to the foliage thereof or to soil containing the seeds or other propagating organs thereof, a crop-yield enhancing amount of a compound having the following formula, EMI116.1 wherein W5 is H, F or C1; X5 is H, straight or branched C1-C4 alkyl, halogen, CN, NO2, CH2CN. OCHF2, OCF2CHF2, OCF3, CF3, C1-C4 alkoxy, EMI116.2 tetrahydro- 2Hpyran-2-yl, OH, C(OH)2CF3, SCH3, COCH3, N(CH3)2, COOCH3 or CH2OR3 where R3 is H or CH3; Y5 is H, OH, OCH3, CH3 or halogen; Z5 is H, CH3, halogen, OCH3 or CF3 ; R4 is H, CH3 C2H5 or CF3; R5 is H or CH3; R6 is NO2 or CN; ni is an integer of 0 I or 2; n is an integer ol () or 1 and the salts or tautomers thereof. 9. A method according to Claim 8, wherein n is O; R6 is NO2; Y5 is H, C1 or F; Z5 is H, CH3 or C1; X5 is CF3, halogen, COCH3, OCH3, CH3, OC2H5, COOCH3, C(OH)2CF3, or OCF3, OCHF2; R5 is H; W5 is H; provided that when X5 is C1 and Z5 is H, Y cannot be CH3; and the salts or tautomers thereof. 10. A method according to Claim 8, wherein m is O; n is 1; R4 is H or CH3; R5 is H; R6 is NO2 or CN; W5 is H or F; X5 is H, F, CH3, OH, C1-C4 alkoxy; Y5 is H or F; Z5 is H, CH3 or OCH3; and the salts or tautomers thereof. 11. A method according to Claim 8, wherein said compounds are l-nitro-3-(a,a,a,4-tetrafluoro-mtolyl)-guanidine, l-(m-methoxybenzyl)-3-nitroguanidine, l-(3,5-dichlorophenyl)-3-nitroguanidine, 1-benzyl-3nitroguanidine, l-nitro-3-(a,a,a-trifluoro-m-tolyl)- guanidine, 1-(2-fluoro-5-methylbenzyl)-3-nitroguanidine, l-(a-methylbenzyl)-3-nitroguanidine, or mixtures thereof; said crop is potatoes; and said compound is applied at a rate of about 0.06 to 5.0 kg/ha. 12. A method for inducing a cytokinin-like response in ornamental and crop plants, said method characterized by: applying to the foliage of said plants or to soil containing seeds or other propagating organs thereof, a cytokinin-like-response-inducing amount of a compound represented by the formula, EMI118.1 wherein W5 is H, F or C1; X5 is H, straight or branched C1-C4 alkyl, halogen, CN, N02, CH2CN. OCHF2, OCF2CHF2, OCF3, CF3, C1-C4 alkoxy, EMI118.2 tetrahydro-2Hpyran-2-yl, OH, C(OH)2CF3, SCH3, COCH3, N(CH3)2, COOCH3 or CH20R3 where R3 is H or CH3; Y5 is H, OH, OCH3, CH3 or halogen; Z5 is H, CH3, halogen, OCH3 or CF3; R4 is H, CH3 C2H5 or CF3; R5 is H or CH3; R6 is N02 or CN; m is an integer of O, 1 or 2; n is an integer of O or 1; and the salts or tautomers thereof. 13. A method according to Claim 12, wherein said compounds are l-(m-hydroxybenzyl)-3-nitroguanidine, l-benzyl-3-cyanoguanidine, 1-cyano-3-(a,a,a-trifluoro- m-tolyl)-guanidine, 1-(m-bromophenyl)-3-nitroguanidine, or mixtures thereof. 14. A method for inhibiting senescence and extending the freshness and shelf life of harvested fruits, vegetables, and ornamentals, said method characterized by: applying to said harvested fruits, vegetables, or ornamentals, a senescence-inhibiting amount of a compound represented by the formula, EMI119.1 wherein W5 is H, F or C1; X5 is H, straight or branched C1-C4 alkyl, halogen, CN, NO2, CH2CN. OCHF2, OCF2CHF2, OCF3, CF3, C1-C4 alkoxy, EMI119.2 tetrahydro-2Hpyran-2-yl, OH, C(OH)2CF3, SCH3, COCH3, N(CH3)2, COOCH3 or CH2OR3 where R3 is H or CH3; Y5 is H, OH, OCH3, CH3 or halogen; Z5 is H, CH3, halogen, OCH3 or CF3 ; R4 is H, CH3 C2H5 or CF3; R5 is H or CH3; R6 is N02 or CN; m is an integer of O, 1 or 2; n is an integer of O or 1; and the salts or tautomers thereof. 15. A method for the preparation of a compound represented by the formula, EMI119.3 wherein X1 is COCH3, halogen, CN, CH2CN, C(OH)2CF3, OCHF2, OC F3 CH3, SCH3, CF3, NO2, OCF2CHF2, OCH3, N(CH3)2, COOCH3 or CH20R3 where R3 is H or CH3; Y1 is H, halogen, CH3; Z1 is H, CH3, halogen, OCH3 or CF3; R is H or CH3; with the provisos that when X1 is CH3, OCH3, F, Cl or Br and R is H, then Y1 and Z1 cannot both be hydrogen; and when X1 is Cl and Z1 and R are each hydrogen, then Y1 cannot be methyl, said method characterized by: reacting an appropriately-substituted aniline represented by the formula, EMI120.1 wherein X1, Y1, and Z1 are as described above, with about an equimolar amount of an N-alkyl-N-nitroso-N'nitroguanidine represented by the formula, EMI120.2 wherein R' is C1-C4 alkyl; in the presence of an aqueous alcoholic solution; heating the reaction mixture to about 400C; treating the same with a strong base; thereafter, removing the alcohol from said reaction mixture; acidifying the remaining residue; and optionally, treating the resulting compound with methyl iodide and silver oxide to obtain the corresponding compound wherein R is CH3. 16. A method for the preparation of a compound represented by the formula, EMI120.3 wherein X2 is H, OH, straight or branched C1-C4 alkoxy, SCH3, halogen, OCF3, CF3, straight or branched C1-C4 alkyl or EMI120.4 tetrahydro-2H-pyran-2-yl; Y2 is H or ; Z2 is , H, CH3 or OCH3; W2 is H or F; m is an integer of O, 1 or 2; R2 is H, CH3, 02H5 or CF3 ; with the provisos that when m is 0 and R2 is H or CH3, then W2, X2, Y2, and Z2 cannot all be hydrogen; and when m is 1, then R2, W2, X2, Y2, and Z2 cannot all be hydrogen, said method characterized by: reacting a compound represented by the formula, EMI121.1 wherein W2, X2, Y2, Z2, R2 are as described above; m is an integer of 0, 1 or 2; n is an integer of 0 or 1; with nitroguanidine in a solvent such as water; and heating the reaction mixture to about 50 C to 75 C for one hour. 17. A method for the preparation of a compound represented by the formula, EMI121.2 wherein X3 is 0CH3, CH3, halogen or CF3; Y3 is H, OH or halogen; Z3 is H or C1; with the provisos that Y3 and Z3 can both be hydrogen only when X3 is OCH3; and when X3 and Y3 are each C1, Br or I, then Z3 cannot be hydrogen; and when X3 is CH3 and Z3 is H, then Y3 cannot be C1, said method characterized by: dispersing an appropriately-substituted aniline represented by the structural formula, EMI122.1 wherein X3, Y3, and Z3 are as described above, in a strong mineral acid; and admixing the thus-formed reaction mixture with at least an equimolar amount of sodium dicyanamide in water. 18. A method for the preparation of a compound represented by the formula, EMI122.2 wherein W4 is H or F; X4 is straight or branched C1-C4 alkoxy, straight or branched C1-C4 alkyl or F; with the provisos that when W4 is F, X4 is H and when W4 is H, then X4 is C1-C4 alkoxy, C1-C4 alkyl or F, said method characterized by: dispersing an appropriatelysubstituted benzylamine represented by the structural formula, EMI122.3 wherein X4 and W4 are as described above, in a strong mineral acid; and admixing the thus-formed reaction mixture with at least an equimolar amount oE sodium dicyanamide in water. 19. A method for inducing maturation of crops, such as wheat or barley, said method characterized by: applying to the foliage thereof or to soil containing the seeds or other propagating organs thereof, a maturation-inducing amount of a compound having the following formula, EMI123.1 wherein W5 is H, F or C1; X5 is H, straight or branched C1-C4 alkyl, halogen, CN, NO2, CH2CN. OCHF2, OCF2CHF2, OCF3, CF3, C1-C4 alkoxy, EMI123.2 tetrahydro-2Hpyran-2-yl, OH, C(OH)2CF3, SCH3, COCH3, N(CH3)2, COOCH3 or CH20R3 where R3 is H or CH3; Y5 is H, OH, OCH3, CH3 or halogen; Z5 is H, CH3, halogen, OCH3 or CF3; R4 is H, CH3 02H5 or CF3; R5 is H or CH3; R6 is N02 or ON; m is an integer of O, 1 or 2; n is an integer of O or 1; and the salts or tautomers thereof.

Inventors: PAVLISTA, ALEXANDER DIMITRI, SPELTZ, LAURINE MARY, WALWORTH, BRYANT LEONIDAS
Applicants: AMERICAN CYANAMID COMPANY
Application year: 1983
Main classification: C07C129
IPC codes: C07C279, C07C313, C07C323, A01N47, C07C239, C07D317, C07D309, C07C67