bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrolysis of Atrazine on Soil Colloids
Authors: Skipper H. D. , Volk V. V. , Mortland M. M. , Raman K. V.
Published: May 2019

Infrared spectroscopy was used to study the hydrolysis of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] upon interaction with homoionic soil colloids. Montmorillonite, an allophanic soil clay, and a montmorillonitic Coker soil clay were saturated with H+, Al3+, Cu2+, and Ca2+and treated with atrazine and hydroxyatrazine [2-hydroxy-4-(ethylamino)-6-(isopropylamino)-s-triazine]. Hydrolysis of atrazine was evaluated by the presence of a strong hydroxyatrazine carbonyl absorption band at 1745 cm-1. The H+- and Al3+-saturated montmorillonite and montmorillonitic Coker soil clay promoted atrazine hydrolysis while Ca2+- or Cu2+-saturated montmorillonite did not. A small degree of atrazine hydrolysis was detected in the Cu2+-Coker soil clay. Dehydration of Ca2+- or Cu2+-Coker soil clay after equilibration with atrazine increased the hydrolysis of atrazine. The allophanic soil clay did not catalyze the hydrolysis of atrazine when the exchange complex was saturated with H+, Al3+, Ca2+, or Cu2+. Moreover, Al3+-allophane was not sufficiently acidic to protonate hydroxyatrazine. Thus, a major difference exists between soil allophanic colloids, montmorillonitic soil clays, and montmorillonite as catalysts in the protonation and hydrolysis of atrazine.
Some Comments on the Assessment of Joint Action in Herbicide Mixtures
Authors: Morse Pamela M.
Published: May 2019

Methods of assessing and describing the joint action of materials as herbicides are reviewed, and the shortcomings of the terms synergism and antagonism are discussed. Some of the lack of agreement on their meaning and evaluation is attributed to failure to define or recognize appropriate models to represent absence of synergism (and antagonism). General analytical and graphical procedures are presented, and for two simple models, the additive-dose model (ADM) and the multiplicative-survival model (MSM), the dose-response curves and isobols are compared. Three examples from recent literature are reworked.
Enhancement of Energy Conservation by Hill Reaction Inhibitors in Isolated Spinach(Spinacia oleracea)Chloroplast Fragments
Authors: Bethlenfalvay G. J. , Castelfranco P. A.
Published: May 2019

The effect of diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], desmedipham [ethylm-hydroxycarbanilate carbanilate(ester)], propanil (3′,4′-dichloropropionanilide), and dibromothymoquinone (DBMIB) (2,5-dibromo-3-methyl-6-isopropyl-p-benzoquinone) on proton translocation and photophosphorylation in isolated spinach(Spinacia oleraceaL.) chloroplast fragments was investigated. In the absence of added cofactors, O2, or artificial electron acceptors, cyclic electron transport occurred, which was coupled to energy conservation. Under aerobic conditions O2acted as the terminal acceptor in non-cyclic electron transport. Proton translocation and photophosphorylation in the cyclic process were enhanced by diuron, desmedipham, and propanil, while in the non-cyclic process they were inhibited by all three herbicides. DBMIB inhibited proton translocation and photophosphorylation in both processes. Proton translocation and its enhancement increased with increasing light intensities. The finding that the plastoquinone (PQ) antagonist DBMIB disrupted cyclic as well as noncyclic electron flow, while diuron enhanced the cyclic and inhibited the noncyclic process, indicated that the acceptor site for endogenously-cycling electrons must lie between the active site of diuron inhibition and PQ, The close similarity in the behavior of diuron, desmedipham, and propanil suggests that their site of action is the same.
Enzyme Activity in Dormant and Nondormant Large Crabgrass(Digitaria sanguinalis)Seeds Following Hydration
Authors: Biswas P. K. , Devi A. , Roy P. K. , Paul K. B.
Published: May 2019

In order to germinate successfully, large crabgrass [Digitaria sanguinalis(L.) Scop.] seeds require a period of after-ripening. Some changes, either physical, biochemical or both, must occur in these seeds during this after-ripening process. This paper reports the differences in the activities of several enzymes between dormant (non-after-ripened) and nondormant (after-ripened) large crabgrass seeds at various periods of hydration. The total protein content of dormant seeds does not change during imbibition but increases greatly in nondormant seeds at 48 and 76 h of hydration. Initially, nondormant seeds exhibit high alpha-amylase activity and low peroxidase and acid phosphatase activities. Alpha-amylase activity remains unchanged relatively in both dormant and nondormant seeds up to 36 h of hydration, but increases greatly in nondormant seeds at 48 and 76 h of hydration. Peroxidase activity, which is initially low in nondormant seeds, increases substantially at 48 and 76 h of soaking. Acid phosphatase activity in dormant seeds does not change following hydration but is gradually elevated in nondormant seeds with duration of soaking. Lipase activity in dormant seeds remains fairly constant upon hydration. In nondormant seeds, however, the activity gradually decreases with duration of soaking, the decrease being 3 to 4 fold at 76 h of imbibition. Except for lipase, there is a positive correlation in the activities of alpha-amylase, peroxidase, and acid phosphatases with the increase of total protein content of nondormant seeds.
Response of Florunner Peanuts to Planting Dates, Herbicide Sequences, and a Systemic Insecticide
Authors: Hauser E.W. , Buchanan G.A. , Currey W.L. , Ethredge W.J. , Gorbet D.W. , Slaughter J.W. , Swann C.W.
Published: May 2019

Benefin (N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine) applied as a preplant incorporated treatment followed by application at the ground-cracking stage (GC) of a mixture of alachlor [(2-chloro-2′,6′-diethyl-N-(methoxymethyl)acetanilide] plus naptalam (N-1-naphthylphthalamic acid) and dinoseb (2-sec-butyl-4,6-dinitro-phenol) significantly increased the yield of peanuts (Arachis hypogaea L. ‘Florunner’). Delaying treatment with the GC mixture for 10 days did not significantly depress peanut yields when averaged over all soils, although exceptions occurred within soil series. Substantial and consistent yield reductions occurred when the herbicide sequences terminated with five repeated applications of dinoseb, especially on the Ruston soil. Late planted peanuts often were more susceptible to intensive herbicide treatments than the early plantings. Beginning intensive sequential treatments with vernolate (S-propyl dipropylthiocarbamate) reduced yields more than when benefin initiated the sequence. Average yields of Florunner peanuts were increased significantly by the insecticide disulfoton (O,O-diethyl S[2-(ethylthio)ethyl]phosphorodithioate) on the Greenville and Ruston soil series, but not on the Dothan soil. The disulfotan x herbicide interaction was not significant. Herbicides interacted more frequently with planting date, treatment time, soil series, and year than did disulfoton.
Phytochrome Distribution in Johnsongrass Rhizomes
Authors: Duke S.O. , Williams R.D.
Published: May 2019

Phytochrome was assayed in vivo in the rhizomes of 12 to 14-week old johnsongrass [Sorghum halapense(L.) Pers.] plants. The phytochrome levels decreased basipetally from the apex through the eighth node. The decrease was logarithmic on a dry weight basis, but less rapid on a per segment basis. On a dry weight basis, higher phytochrome measurements were obtained with samples from the interior of the rhizome than from the external regions. The far-red absorbing form of phytochrome (Pfr) was shown to be very labile at 25 C in johnsongrass rhizomes. These results provide a basis for examining photomorphogenic responses of rhizomes to light and for correlating these responses to phytochrome photophysiology.
Mechanism of Atrazine Resistance in Lambsquarters and Pigweed
Authors: Radosevich S.R.
Published: May 2019

Studies were conducted to determine the effect on absorption and metabolism of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] by atrazine-susceptible (S) and -resistant (R) biotypes of common lambsquarters (Chenopodium albumL.) and redroot pigweed (Amaranthus retroflexusL.). The response of isolated chloroplasts of susceptible and resistant biotypes of each species was also studied. In both species the two biotypes absorbed atrazine equally well and were unable to differentially metabolize the herbicide. The photochemical activity of R chloroplasts isolated from each species was not inhibited by atrazine but S chloroplasts were severely inhibited.
Weeds and Water in World Food Production
Authors: Holm LeRoy
Published: May 2019

We have come together to discuss the way in which weeds and water work together to influence yields in agriculture. In the small allotment of time available to us this morning a review of basic knowledge about this relationship would be so general that it could help no one. I believe it would be more appropriate, and more helpful for a group so large, if I tell you of some of the hard realities which come to bear on food production across the world because of this relationship of weeds with moisture. These stories will have to do with such practical matters as the expansion of the world's most important crop, and the difference between good and bad crops on the two sides of the same river under identical climatic conditions in Middle Asia.
Effect of Tricalcium Arsenate Formulations on Control of Annual Bluegrass (Poa annua)
Authors: Carrow R.N. , Rieke P.E.
Published: May 2019

The influence of calcium arsenate (48% w/w tricalcium arsenate) rate, physical form, time of application, and phosphorus (P) rate on the growth of annual bluegrass (Poa annua L.) and Bray P1 extractable arsenic (As) were investigated. Both powder and granular formulations reduced clipping yields and enhanced extractable As levels. Higher initial soil As activity and significantly better control were obtained in one study when the powder formulation was used. Similar levels of control were achieved whether the As was applied prior to germination or to the mature turf. Soil P-levels did not influence the effectiveness of either As formulation.
A Method for Simulating Subsurface Disposal of Herbicides
Authors: Cupello J.M. , Young A.L. , Smith J.C.H.
Published: May 2019

Specially designed growth boxes were used to simulate field subsurface injection of phenoxy herbicides. Sorghum (Sorghum vulgarePers.) seedlings were grown in stainless steel containers (inserts) which were placed in plexiglass boxes containing a soil layer that had received 2,240 kg/ha of a 50:50 mixture of then-butyl esters of 2,4-D [(2,4-dichlorophenoxy)-acetic acid] and 2,4,5-T [(2,4,5-trichlorophenoxy)-acetic acid]. Plant height data were collected periodically for all treatments. Subsurface herbicide application to both intact and cut root systems significantly altered root growth. Plants with treated, intact root systems showed retarded growth which became more pronounced with time. Plants whose root systems were treated, and cut on day 22, showed an initial acceleration of growth; a trend which eventually reversed itself and resulted in control plant height exceeding that of treated plants.
The Effect of Urea on Atrazine Uptake from Soil
Authors: Minshall W.H. , Sample K.C. , Robinson J.R.
Published: May 2019

An application of urea to the soil of potted tomato plants (Lycopersicon esculentumMill. ‘John Baer’) increased the translocation of atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] to the shoots of the plants. The rate of uptake of atrazine was more closely related to the rate of transpiration than it was to the rate of stump exudation or root pressure. The presence of urea did not change the metabolism of atrazine by the plants. Over the range of xylem flows from 12 ml/24 h in detopped roots (root pressure) to 211 ml/24 h in intact plants (transpiration) the concentration of atrazine in the xylem stream was approximately the same suggesting that the uptake mechanism tends to maintain a constant concentration of atrazine in the xylem stream.
Differential Activity of Three Diphenyl Ether Herbicides
Authors: Fadayomi Omosuyi , Warren G.F.
Published: May 2019

The tolerance of four legume species to nitrofen (2,4-dichloro-phenyl-p-nitrophenyl ether), fluorodifen (p-nitrophenylα,α,α-trifluoro-2-nitro-p-tolyl ether), and oxyfluorofen [2-chloro-1-(3-ethoxy-4-nitro-phenoxy)-4-(trifluoro-methyl)benzene] was investigated both pre- and postemergence in the greenhouse. Seedlings of species that emerged most rapidly seemed to be most tolerant to preemergence herbicide applications. There was no direct relationship between preemergence and postemergence tolerance. Oxyfluorfen was found to be at least 10 times as active as the other two herbicides both pre- and postemergence. Field experiments were conducted at two locations in Indiana to test the effect of method of application on the activity and selectivity of fluorodifen and oxyfluorfen on soybean [Glycine max(L.) Merr. ‘Wayne’] and greenbean (Phaseolus vulgarisL. ‘Spartan Arrow’). Crop injury and grass weed control were reduced by incorporation of the herbicides 8 cm deep in a silt loam. Method of application did not affect the activity of the herbicides on a sandy soil low in organic matter. Soybean was more tolerant than greenbean to both herbicides when applied preemergence but oxyfluorfen was far more active than fluorodifen on both crops.
Intraspecific Competition of Purple Nutsedge (Cyperus rotundus) Under Greenhouse Conditions
Authors: Williams R.D. , Quimby P.C. , Frick K.E.
Published: May 2019

The effects of intraspecific competition on the growth and development of purple nutsedge (Cyperus rotundusL.) were studied under greenhouse conditions. Increases in plant density increased the dry weight accumulation on a per pot basis but decreased the dry weight accumulation on a per plant basis. The partitioning of dry weight, whether on a per pot or per plant basis, indicated a shift in the method of reproduction as to density. Under low density conditions more dry weight was partitioned into inflorescences than into tubers. However, under high density conditions more dry weight was partitioned into tubers rather than inflorescences. Dry weight partitioned into rhizomes did not vary as to density. Dry weight partitioned into shoots and roots decreased with the concomitant increase in dry weight partitioned into reproductive structures. This shift to vegetative reproduction under stress conditions caused by competition provides further insight into the difficulties of controlling purple nutsedge.
Absorption and Translocation of Terbutryn and Fluometuron in Cotton (Gossypium hirsutum) and Snapbeans (Phaseolus vulgaris)
Authors: Rubin B. , Eshel Y.
Published: May 2019

The absorption and translocation of14C-terbutryn [2-(tert-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine] and14C-fluometuron [1,1-dimethyl-3-(α,α,α,-trifluoro-m-tolyl) urea] in cotton (Gossypium hirsutumL. ‘SJ-1′) and snapbean (Phaseolus vulgarisL. ‘Tenderette’) were studied.14C-terbutryn supplied to the roots accumulated in the root system of both species. However, snapbean plants (sensitive) absorbed and translocated more14C to the shoots than cotton (tolerant), followed by rapid distribution in the leaf mesophyll tissue. In cotton, the translocated14C-terbutryn accumulated in stems, petioles, and leaf veins. Excised cotton roots absorbed more14C-terbutryn than excised snapbean roots. The uptake and distribution pattern of root-applied14C-fluometuron was similar in both species. Foliar application to the primary leaf of snapbeans and to one cotyledon of cotton resulted in 2% of14C-terbutryn transported acropetally to younger leaves with no basipetal movement. Translocation of14C-fluometuron from the site of foliar application was two or three times faster than terbutryn with significant basipetal transport in both species.
Photodecomposition of Eleven Dinitroaniline Herbicides
Authors: Parochetti J. V. , Dec G. W.
Published: May 2019

Decomposition of 11 dinitroaniline herbicides was determined following 7 days exposure to unfiltered solar radiation in July and compared with that in the dark. Radiolabeled herbicides were applied at 1 kg/ha to dry soil thin layer plates. Decomposition of all dinitroanilines was higher when exposed to sunlight than if held in the dark under otherwise similar conditions. Thermal decomposition was noted for all dinitroanilines except profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine] and dinitramine(N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine). Photodecomposition for each herbicide was: 7.8% AC 92390 [N-(1-ethylpropyl)-2,6-dinitro-3,4-dinitro-3,4-xylidine], 8.2% isopropalin (2,6-dinitro-N,N-dipropylcumidine), 9.0% butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine], 9.9% pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine], 17.1% benefin(N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine), 18.4% trifluralin (α,α,α-trifluoro-2,6-dinitro-N-N-dipropyl-p-toluidine), 26.6% oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide), 30.4% fluchoralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], 40.6% nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline], 47.6% profluralin, and 72.3% dinitramine.
Inhibition of Carotenoid Synthesis by Fluridone and Norflurazon
Authors: Bartels P. G. , Watson C. W.
Published: May 2019

Fluridone {1-methyl-3-phenyl-5-[3-(trifluromethyl)phenyl]-4(1H)-pyridinone} and norflurazon [4-chloro-5-(methylamino)-2-(α,α,α-trifluoro-m-tolyl)-3(2H)-pyridazinone] inhibited carotenoid synthesis in wheat(Triticum aestivumL. ‘Maricopa’) seedlings and caused the accumulation of colorless carotenoid precursors, phytoene, and phytofluene. These data suggested that dehydrogenation reactions following phytoene formation were inhibited by the herbicides. Chlorophyll accumulated in the treated seedlings grown under 10 lux of light but was destroyed in seedlings illuminated with 16 klux of light. Seedlings illuminated with 16 klux of light lacked chloroplast ribosomes and normal ultrastructure whereas dark grown seedlings contained pastid ribosomes and had normal etioplast ultrastructure. The disruption of the chloroplasts and loss of chlorophyll was due to the absence of carotenoids in the treated plants, which would normally act to protect the chloroplasts from photodestruction.
Separating Seed by Species with CaCl2 Solutions
Authors: Johnston S. K. , Crowley R. H. , Murray D. S.
Published: May 2019

A technique using CaCl2 solutions for separating seed of approximately equal size and/or shape by relative density was developed using nine hard-seeded weed species and four soybean [Glycine max (L.) Merr.] cultivars having an average density of 1 g/ml or above. Relative seed densities were determined by the water displacement method. From a seed mixture of nine weed species and soybeans, three groups were obtained: Group I, sicklepod (Cassia obtusifolia L.) and smallflower morningglory [Jacquemontia tamnifolia (L.) Griseb]; Group II, hemp sesbania [Sesbania exaltata (Raf.) Cory], tall morningglory [Ipomoea purpurea (L.) Roth], cypressvine morningglory (Ipomoea quamoclit L.), and ivyleaf morningglory [Ipomoea hederacea (L.) Jacq.]; and Group III, soybeans, balloonvine (Cardiospermum halicacabum L.), and velvetleaf (Abutilon theophrasti Medic). Ipomoea lacunosa L. was divided between Group II and Group III due to the range of seed density within the seedlot. The minimum relative CaCl2 solution densities required to separate these seed were 1.38, 1.30, and 1.25 g/ml for Group I, Group II, and Group III, respectively. Further separation into individual species within a group was accomplished by screening in some cases. Sicklepod was separated effectively with this technique from seed screenings obtained from a commercial seed processing plant. There was no effect on germination from soaking weed seed or soybean for 40 min in the CaCl2 solution.
Aspects of Germination, Emergence, and Seed Production of ThreeIpomoeaTaxa
Authors: Gomes L. F. , Chandler J. M. , Vaughan C. E.
Published: May 2019

The influence of seed age, planting depth, and temperature on the germination and emergence of ivyleaf morningglory [Ipomoea hederacea(L.) Jacq. var.hederacea], white morningglory(Ipomoea lacunosaL.), and entireleaf morningglory(Ipomoea hederaceavar.integriusculaGray) was studied by using pure seed of each taxa that were collected in 1972, 1973, and 1974. Germination of acid-scarified white and entireleaf morningglory seed ranged from 64 to 98% at continuous 20, 25, 30, 35, and 40 C and at an alternating 20/30 C cycle. The ivyleaf morningglory germination range was 50 to 98% at these temperatures, except at 40 C germination was <25%. Germination of nonscarified seed was generally 30 to 60% lower than scarified seed for the three taxa. Germination of seed collected in 1972 for all three taxa was less than 10% with 6 days of exposure to 45 C and 100% relative humidity, and germination of seed collected in 1973 and 1974 ceased with 12 days of exposure. Maximum emergence for all taxa occurred at planting depths of 1.3 and 2.5 cm. Seed age influenced seedling emergence of white morningglory and ivyleaf morningglory but not entireleaf morningglory. Total numbers of seed produced per plant for white, entireleaf, and ivyleaf morningglory were 15,200, 14,600, and 5,800, respectively.
Some Germination Characteristics in Common Lambsquarters(Chenopodium album)
Authors: Chu Chang-Chi , Sweet R. D. , Ozbun J. L.
Published: May 2019

Germination of fruit of common lambsquarters(Chenopodium albumL.) from three out of four sources was enhanced by 9 to 41% by removal of the fruit coat, and by 21% by washing the fruit for 70 h. Brown-black seed germinated more rapidly than the black and brown seed after washing for 70 h. The washing treatment appeared to remove some unknown inhibitors. After washing, seed germination was found to be positively correlated with seed size.
Soil Persistence of Isopropalin, Nitralin, and Trifluralin
Authors: Romanowski R. R. , Libik A. W.
Published: May 2019

The persistence of isopropalin (2,6-dinitro-N,N-dipropylcumidine), nitralin [4-(methylsulfonyl)-2,6-dinitro-N,N-dipropylaniline] and trifluralin(a,a,a-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) applied at recommended (1X) and high (2X) rates was studies in the field on two soils. A sorghum [Sorghum bicolor(L.) Moench ‘RS 610’] root bioassay showed that the recommended rates of the herbicides caused 20% or less root inhibition at the end of the growing season in 1972. Both nitralin and trifluralin were more persistent in 1974 than in 1972 as shown by the root bioassay and growth of fall-sown rye(Secale cerealeL.). The yield of sweet corn(Zea maysL. var.rugosaBonaf. ‘Gold Cup’) was not significantly reduced when grown 1 yr after the initial application of the herbicides.
Action of EMD-IT 5914 on Chloroplasts
Authors: Kunert K. J. , Böger P.
Published: May 2019

The experimental herbicide EMD-IT 5914 [difunon, 5-dimethyl-amino-methylene-2-oxo-4-phenyl-2,5-dihydrofurane-carbonitrile-(3)] was applied to unicellular algae and its effect on growth, oxygen evolution and photosynthetic electron transport measured. Inhibition of biosynthesis of chloroplast pigments was evaluated in relation to the activities of porphobilinogenase and δ-aminolevulinic acid dehydratase. The only direct effect of the herbicide was an inhibition of carotenoid biosynthesis but not of photosynthetic electron transport or enzymic activities connected with porphyrin biosynthesis. Chlorophyll bleaching is considered to be a secondary process.
Comparative Triazine Effects Upon System II Photochemistry in Chloroplasts of Two Common Lambsquarters(Chenopodium album)Biotypes
Authors: Machado V. Souza , Arntzen C. J. , Bandeen J. D. , Stephenson G. R.
Published: May 2019

Biotypes of several annual broadleaved weeds tolerant to 2-chloro-s-triazines have been recorded, including common lambsquarters(Chenopodium albumL.). The mechanism of resistance in common lambsquarter was based on the differential inhibition of the Hill reaction in chloroplasts by atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine]. Chlorophyll fluorescence and electron transport assays were used with isolated chloroplasts of atrazine-tolerant and susceptible biotypes, to determine the effect of atrazine and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] on photosystem II (PS II) activity, differential atrazine penetration of the chloroplast envelope, and relative tolerance to chloro, methoxy, and methylthio triazines. Atrazine and diuron inhibited electron transport on the reducing side of PS II in susceptible biotype chloroplasts. In tolerant biotype chloroplasts only diuron inhibited electron transport whereas atrazine had only slight effects. There were no differences in the chloroplast membrane permeability to atrazine in the two biotypes. Chloroplasts of the atrazine-tolerant biotype of common lambsquarters were also tolerant to the other classes of triazines tested.
Interaction of Metribuzin and Trifluralin with Soil Type on Soybean(Glycine max)Growth
Authors: Moomaw R. S. , Martin A. R.
Published: May 2019

Field experiments were conducted on a Moody silty clay loam (pH 6.5) and a Crofton silt loam (pH 7.9) to evaluate the influence of soil texture and pH on metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazin-5(4H)-one] toxicity to soybeans [Glycine max(L.) Merr. ‘Amsoy 71’] as influenced by trifluralin [α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine]. One Crofton silt loam site contained atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] residue. Soybean growth and yield was not significantly affected by metribuzin and trifluralin applications on the Moody silty clay loam. On the Crofton silt loam without atrazine residue, substantial early season soybean injury from metribuzin did not result in significantly reduced soybean yield. Atrazine residue from previous row banding on corn(Zea maysL.) on the Crofton silt loam reduced soybean tolerance to metribuzin but normal use rates of 0.4 kg/ha metribuzin did not significantly reduce soybean yield. Trifluralin reduced early season soybean injury from metribuzin but this effect was not reflected in soybean yield. Metribuzin injury to soybeans was greater in years when more rainfall and cooler temperatures occurred following herbicide application. Metribuzin applied either preplant incorporated with or as an overlay on trifluralin resulted in equal soybean injury and yield.
Mechanical, Cultural, and Chemical Control of Weeds in a Sorghum-Soybean(Sorghum bicolor)–(Glycine max)Rotation
Authors: Burnside O. C.
Published: May 2019

A crop rotation of sorghum [Sorghum bicolor(L.) Moench] and soybeans [Glycine max(L.) Merr.] with various weed control treatments was conducted from 1968 to 1975 at Lincoln, Nebraska, in order to improve weed control in these two crops. Poor weed control during one growing season increased weed growth and decreased yields of succeeding crops. Trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 1.1 kg/ha on soybeans showed greater soil carryover toxicity to sorghum planted 12 months later than did atrazine [2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine] at 3.4 kg/ha on sorghum to subsequently planted soybeans. Under this crop rotation green foxtail [Setaria viridis(L.) Beauv.], tall waterhemp [Amaranthus tuberculatos(Moq.) J. Sauer], and large crabgrass [Digitaria sanguinalis(L.) Scop.] decreased; whereas, velvetleaf(Abutilon theophrastiMedic), sunflower(Helianthus annuusL.), and Pennsylvania smartweed(Polygonum pensylvanicumL.) increased. Germinating weed seedlings from soil samples were greater in weedy check plots during the final years of the crop rotation due to a buildup of seed from those species that increased. Handweeding, herbicides, and plowing reduced weed populations, weed competition, and increased sorghum and soybean yields.
Differential Varietal Tolerance of Peach(Prunus persica)Seedlings to Glyphosate
Authors: Marriage P. B. , Khan S. U.
Published: May 2019

The translocation and effects of glyphosate [N-(phosphonomethyl)glycine] were determined in greenhouse-grown peach [Prunus persica(L.) Batsch] seedlings obtained from different seed parents. Two lower branches of 10-week-old seedlings of Rutgers Red Leaf, Bailey, Kalamazoo, Siberian C, and Harrow Blood were sprayed with 0.9 to 18 mg of glyphosate per plant. Seedlings of Harrow Blood, Bailey, and Kalamazoo were more susceptible to injury than were those of Siberian C and Rutgers Red Leaf. Glyphosate at 6, 9, and 18 mg produced necrotic areas on the stems of the former seedlings and at the higher rates tree death resulted. The Siberian C and Rutgers Red Leaf seedlings showed only chlorosis and malformation of apical leaves although slight stem injury occurred 1 month after treatment. Measurements of plant weight, height, and stem diameter indicated that seedlings of Harrow Blood, Bailey, and Kalamazoo tolerated only 3 mg of glyphosate without growth reduction. This was one-half and one-third of the amount which seedlings of Siberian C and Rutgers Red Leaf tolerated, respectively. The concentration of glyphosate in the treated lower branches and the main stem of the seedlings was determined by thin-layer chromatography. The concentrations in the bark were generally similar among all seedlings. Differential tolerance, therefore, was not based on differences in overall glyphosate concentration in tissues but on protective or resistance mechanisms present only in seedlings of Siberian C and Rutgers Red Leaf.
Factors Affecting the Translocation of14C-Mefluidide in Soybeans(Glycine max), Common Cocklebur(Xanthium pensylvanicum), and Johnsongrass(Sorghum halepense)
Authors: McWhorter C. G. , Wills G. D.
Published: May 2019

Absorption and translocation of14C-mefluidide {N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl] amino] phenyl] acetamide} in soybeans [Glycine max(L.) Merr. ‘Lee 68’], common cocklebur(Xanthium pensylvanicumWallr.), and johnsongrass [Sorghum halepense(L.) Pers.] were evaluated under different environmental conditions with and without adjuvants. At a constant level of 40 or 100% relative humidity (RH), an increase in air temperature from 22 to 32 C resulted in a two- to three-fold increase in absorption and a four- to eight-fold increase in translocation of the14C in soybeans following application to the second trifoliolate. At constant 22 or 32 C an increase from 40 to 100% RH resulted in less than a two-fold increase in absorption or translocation of14C in soybeans. Autoradiograms indicated that movement of the14C was primarily into leaves above the treated area. Translocation of14C was significantly greater following application to the lower stem than to leaves. In common cocklebur,14C absorption increased about three-fold at both 22 and 32 C with an increase from 40 to 100% RH following application to the second alternate leaf. At both levels of RH, absorption and translocation increased as the temperature was increased from 22 to 32 C. The addition of an adjuvant increased absorption and translocation in common cocklebur under all environmental conditions. When14C-mefluidide was applied without an adjuvant to johnsongrass, absorption increased five- to six-fold at both 22 and 32 C as RH was increased from 40 to 100%. Translocation in johnsongrass was often affected less by variations in temperature than it was in soybeans or common cocklebur. The adjuvant increased absorption and translocation of the14C-label of mefluidide in johnsongrass. The14C-label accumulated primarily in the distal leaf of johnsongrass or in leaves above the treated area.
Milk Thistle(Silybum marianum)Seed Germination
Authors: Young J. A. , Evans R. A. , Hawkes R. B.
Published: May 2019

The germination of seeds (achenes) of milk thistle [Silybum marianum(L.) Gaertn.] was investigated. One month after harvest, milk thistle seeds had afterripening requirements related to germination temperature that limited germination to 10 to 20 C temperatures. The time required to satisfy afterripening requirements was dependent on germination temperature. Generally the higher the incubation temperature during germination, the longer the afterripening requirement (up to a maximum of 5 months). Once afterripening requirements were satisfied, milk thistle seeds germinated over a temperature range of from 0 to 30 C. Optimum germination occurred with 2 to 15 C 16-h cold periods alternating with 10 to 30 C 8-h warm periods. Emergence of milk thistle seedlings decreased with increased burial depth, but substantial emergence occurred from 8 cm. Germination on the surface of the soil or litter was greatly reduced compared to that with slight soil or litter coverage. Potassium nitrate (KNO3) added to the germination substrate at 1.0 mM enhanced the germination of milk thistle seeds at 2 and 5 C incubation temperatures.
Absorption and Translocation of Mefluidide by Soybean(Glycine max), Common Cocklebur(Xanthium pensylvanicum), and Giant Foxtail(Setaria faberi)
Authors: Bloomberg J. R. , Wax L. M.
Published: May 2019

Absorption and translocation characteristics of both root- and shoot-applied mefluidideN-[2,4-dimethyl-5-[[(trifluoromethyl) sulfonyl] amino] phenyl] acetamide were determined in soybean [Glycine max(L.) Merr. ‘Wells’], common cocklebur(Xanthium pensylvanicumWallr.), and giant foxtail(Setaria faberiHerrm.). Absorption of14C-mefluidide was greater through the foliage than the roots of all plant species. Rate of leaf absorption and translocation of14C initially was greater in giant foxtail than in either soybean or common cocklebur, but these processes failed to increase greatly with time in giant foxtail. Absorption and translocation increased over time in soybean and common cocklebur. Soybean absorbed slightly greater quantities of14C-mefluidide than common cocklebur, but by 8 days after labeling, common cocklebur translocated approximately 47% more radio-label out of the treated leaf than soybean. The foliar-applied14C-label appeared to move in the phloem along with the assimilate stream in all species, mainly to areas of high metabolic activity.14C was associated with the root systems and/or nutrient solutions of soybean and giant foxtail, but not of common cocklebur. Exuded material chromatographed as mefluidide. Movement of14C-label in all root-treated plants appeared to be confined within the xylem with older tissue containing greater amounts of14C than the younger tissue. Differences in selectivity between crop and weed species may be partially due to differential mefluidide absorption, translocation, and subsequent concentration in certain plant tissues.
Persistence of Several Dinitroaniline Herbicides as Affected by Soil Moisture
Authors: Savage K. E.
Published: May 2019

The Persistence of substituted dinitroaniline herbicides in soil varied widely. First-order kinetics were used to describe the dissipation rates. Half-lives of the herbicides in moist soil ranged from 29 to 124 days in two soil types under greenhouse conditions. Flooding the soil significantly increased the dissipation rate of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine], and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine]. Dissipation rates of dinitramine(N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) and butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine] were affected to a lesser extent by flooding. Volatilization of trifluralin, fluchloralin, and ethalfluralin [N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl)benzenamine] from Bosket sandy loam was reduced by flooding when compared to volatilization from the same soil with a moisture content equivalent to field capacity. Pendimethalin exhibited low volatility. The effect of flooding on dissipation rates is apparently not due to increased volatilization.
Competition of Four Morningglory(Ipomoeaspp.) Species with Cotton(Gossypium hirsutum)
Authors: Crowley R. H. , Buchanan G. A.
Published: May 2019

Tall morningglory [Ipomoea purpurea(L.) Roth.], pitted morningglory(I. lacunosaL.), ivyleaf morningglory [I. hederacea(L.) Jacq.] and entireleaf morningglory(I. hederaceavar.integruisculaGray) were compared for their competitive ability with cotton(Gossypium hirsutumL.) at weed densities of 4, 8, 16 and 32 weeds/15 m of row. Tall morningglory was the most competitive with yield reductions of as much as 88% at 32 weeds/15 m. The higher populations of tall morningglory also significantly reduced cotton populations, mechanical harvesting efficiency and lint percentage below that in the controls. Pitted morningglory densities twice that of tall morningglory were required to produce cotton responses similar to those induced by tall morningglory. Ivyleaf morningglory and entireleaf morningglory were almost identical in their competitive potentials and were less competitive than the other species evaluated. Their competitive ability was greatly reduced by disease. Competition from morningglories did not consistently affect cotton fiber micronaire, fiber length or strength.
IL CONCETTO DI ÉLITE
Authors: Zannoni Paolo
Published: May 2019

Introduzione

Lo stato di una disciplina è riflesso dallo stato dei suoi concetti. Quindi un'analisi dei concetti fondamentali di una disciplina è un'analisi della disciplina stessa. Se questa affermazione è vera, la principale caratteristica della scienza politica è la confusione. Confusione nei significati, nei referenti e nella significatività dei suoi concetti fondamentali. A nostro parere conoscere le cause di questa confusione costituisce il primo passo verso la riduzione o l'eliminazione della confusione stessa. La logica contemporanea, la filosofia del linguaggio e la filosofia della scienza hanno rivolto grande attenzione al problema della formulazione e della chiarificazione dei concetti. In questo saggio quindi cercherò di utilizzare alcuni contributi di queste discipline nel tentativo di chiarire il concetto di élite.
IL SISTEMA PARTITICO TURCO: ISTITUZIONALIZZAZIONE, POLARIZZAZIONE E FRAMMENTAZIONE
Authors: Özbudun Ergun
Published: May 2019

Introduzione

Lo studio del sistema partitico turco presenta diversi motivi di interesse. Non solo la Turchia è uno dei pochi paesi «in via di sviluppo» che ha conservato un sistema di partiti competitivo per un considerevole lasso di tempo, ma in anni recenti si sono verificati, a livello sistematico, mutamenti significativi che meritano una analisi approfondita. Tali mutamenti sembrano essere associati soprattutto al processo di modernizzazione socioeconomica, per cui lo studio del sistema partitico turco dovrebbe servire a chiarire il rapporto tra modernizzazione e sistema dei partiti. In questo saggio cercherò in primo luogo di descrivere il formato e la meccanica del sistema partitico facendo uso della tipologia di Sartori. Successivamente prenderò in esame alcuni fenomeni piú specifici, quali la polarizzazione, l'istituzionalizzazione e la frammentazione che caratterizzano il «caso turco». In ciascun momento, metterò in evidenza le implicazioni dell'analisi ai fini dello studio dello sviluppo politico. Da ultimo, proverò a formulare delle previsioni sulle possibili direzioni del mutamento del sistema partitico.
INDIPENDENTI DI SINISTRA E PCI. UN PRIMO CONFRONTO DEL LORO COMPORTAMENTO LEGISLATIVO
Authors: Tempestini Attilio
Published: May 2019

Introduzione

Nel nostro paese è diffusa la prassi di presentare, alle elezioni, candidati non iscritti al partito che li mette in lista, e per tale motivo correntemente definiti «indipendenti». A partire dalle consultazioni politiche del 1968, come è noto, uno dei gruppi parlamentari che si costituiscono al Senato — quello della Sinistra Indipendente — è formato quasi nella sua totalità da candidati del genere, eletti nelle liste del PCI (piú esattamente, nelle liste comuni del PCI e del PSIUP in due consultazioni su tre, nel 1968 e nel 1972). Si tratta di candidati che, una volta in parlamento, non si iscrivono al gruppo del partito (o ai gruppi dei partiti) cui devono l'elezione, ma ad un altro gruppo: la Sinistra Indipendente.
Thirty Years of the ‘Jeweled Style’
Authors: O'Hogan Cillian
Published: May 2019

In seventh-century Wiltshire, a scholar-monk began to write classicising Latin poetry. In bold terms he describes himself as the first of the Germanic peoples to write Latin poetry (‘neminem nostrae stirpis prosapia genitum et Germanicae gentis cunabulis confotum in huiuscemodi negotio [i.e. poetry] ante nostram mediocritatem tantopere desudasse’). His programmatic statements cite Virgil explicitly, and allude to Prudentius and Sedulius. His is a poetry that sets out a stall for the beginning of something new, but does so by making clear his predecessors. For Aldhelm, as for much of the Middle Ages, the canonical models of Latin poetry included classical Latin authors as well as the Christian Latin poets of Late Antiquity.
Radioactive species in sea water
Authors: Baxter M. S. , McKinley I. G.
Published: May 2019

Synopsis

Radioactive species, in the dissolved state in sea water, can serve to define rates and directions of water movement. The requirements for such applications are that tracer species be soluble, chemically conservative, of half-life compatible with the process timescale under study and have non-uniform inputs. Boundary and point source inputs generate concentration gradients induced by the known-rate kinetics of radioactive decay. Advection-diffusion and box-model treatments are widely used in data interpretation and examples of a range of applications, based on14C,222Rn,228Ra and fallout nuclides, are presented. Reactive radionuclides such as228Th and210Pb can, on the other hand, be used to trace the fate of many heavy metals introduced into the marine environment. The release of waste from the nuclear industry provides a very convenient source of tracers for coastal waters. This application is illustrated by several studies of Windscale-derived radiocaesium in Scottish waters.
Calcareous sediments on the nearshore continental shelf of western Scotland
Authors: Farrow George E. , Cucci Maurice , Scoffin Terence P.
Published: May 2019

Synopsis

The highest carbonate values are associated with exposed coasts of Lewisian gneiss, reaching 95% CaCO3in SW Tiree: around Iona average values are 80 to 85% CaCO3. Maximum values of 60 to 70% on Islay indicate a regional gradient which reflects a reduced fetch southwards, and a greater input from reworked glacial drift and fluvial material.

High energy carbonate deposits are distinguished by the low diversity of their components, nearly all coming from fragmented molluscs and barnacles. Low energy carbonates have diverse components, with foram and echinoid values each reaching 10%. The ratiomost easily separates the two facies (high energy mean = 18-5: low energy mean = 2-1).

In the immediate offshore tidal-swept zones such as the Sound of Iona barnacles are the most important contributors to the sediment.

Most of the carbonate is fresh and by its relationship to contemporary shore ecology can be shown to be of present-day origin. Offshore, however, relict grains are widespread. Their pitted surfaces are inhabited by very abundant diatoms, and it is tentatively suggested that local carbonate dissolution may be caused by them. Additionally they represent a much more abundant source of silica for eventual silicification of the carbonate than do sponge spicules, which are rare.
The effect of changes in scale on ship and semi-submersible design
Authors: Miller N. S. , De Souza P. M. F. M.
Published: May 2019

Synopsis

The effects of changing scale on ships and semi-submersibles are explored in this paper. In the early part attention is drawn to the wide differences in design practice which exist for large ships with, in particular, a tendency for a lower length to breadth ratio as size is increased. Theoretical reasons for this are given, the principal ones being that this leads to a reduction in steel weight per ton displacement without any large increase in power. It is suggested that this tendency will continue until the weight of the transverse material in the hull approaches that of the longitudinal material. Many other characteristics of the ships improve with lower L/B ratios but manoeuvrability declines and in order to reap the benefit of low L/B designs greater research should be applied to improving this aspect of large ships.

Much greater flexibility in design exists for semi-submersibles since there are no draft restrictions. The paper examines the effects of geometric variations in semi-submersibles and concludes that the stability, dynamic motions and wind and hydrodynamic drag all improve with increasing size but that structural steel weight may not be a significantly lower percentage of the displacement unless design changes are made with changing scale. Attention is drawn to the big improvements in rolling (pitching) performance which would enable large floating platforms to have a very low level of motion. This could have great significance for the siting of petrochemical and other plants at sea.
Underwater inspection of offshore structures
Authors: Milne P. H.
Published: May 2019

Synopsis

Under the Offshore Installations (Construction and Survey) Regulations 1974 all structures established or maintained in UK waters must possess a valid certificate of fitness. To obtain this certificate annual visual inspections of parts of the structure must be carried out both above and below water. A major survey of the complete structure or platform is required every five years.

Underwater inspections may be carried out down to 50 m by divers on surface demand. Below 50 m when divers are involved it is essential to use either a diving bell or lock-out submersible. To avoid saturation diving and reduce diving hazards, the unmanned submersible has been developed as an underwater inspection tool.

Various navigation systems have been developed for offshore position fixing. Deepwater navigation and surveying relies on a combination of surface radio stations and seabed underwater acoustic transponders. Platform navigation for underwater inspection and maintenance is a major problem due to poor diving access and few underwater reference points.

The inefficiency of the present diver operated navigation and survey systems round platforms is now being investigated by a research team from the University of Strathclyde. Preliminary tests of equipment have already been carried out in a diving tank and at sea.
The history and future of the North Sea benthos
Authors: Norton P. E. P.
Published: May 2019

Synopsis

This is a brief review intended to supply bases for prediction of future changes in the North Sea Benthos. It surveys long-term changes which are affecting the benthos. Any prediction must take into account change in temperature, depth, bottom type, tidal patterns, current patterns and zoogeography of the sea and the history of these is briefly touched on from late Tertiary times up to the present. From a prediction of changes in the benthos, certain information concerning the pelagic and planktonic biota could also be derived.