bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of Hemp Dogbane with Foliar and Soil Applied Herbicides
Authors: Schultz M. E. , Burnside O. C.
Published: July 2010

Hemp dogbane (Apocynum cannabinum L.) has become a serious weed problem in eastern and southcentral Nebraska. Greenhouse and field studies were conducted to evaluate control of hemp dogbane with herbicides. In greenhouse studies, postemergence applications of herbicide combinations which included 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] ester, 2,4‐D amine, or glyphosate [N‐phosphonomethyl)glycine] controlled hemp dogbane more effectively than those containing dicamba (3,6‐dichloro‐o‐anisic acid) or amitrole (3‐amino‐s‐triazole). Control was greater with equivalent rates of 2,4‐D ester than with 2,4‐D amine. Control with 2,4‐D increased with longer slide‐chain lengths of both ester and amine formulations. Postemergence control of hemp dogbane with herbicides was erratic in field studies over years. Glyphosate generally provided better control than 2,4‐D, and amitrole consistently gave poor control. A preliminary study showed that growth of hemp dogbane from crown and lateral roots could be suppressed or controlled with preplant treatments of thiocarbamate herbicides. Increasing order of effectiveness for controlling hemp dogbane was vernolate (S‐propyl dipropylthiocarbamate), EPTC (S‐ethyl dipropylthiocarbamate), and butylate (S‐ethyl diisobutylthiocarbamate). In the field, butylate + R‐25788 (N,N‐diallyl‐2,2‐dichloroacetamide) and EPTC + R‐25788 at 4.5 + 0.2 kg/ha provided good control (60 to 98%) of hemp dogbane during the first 2 months after corn (Zea mays L.) planting, but decreased to 0 to 40% at harvest. Higher rates of butylate + R‐25788 controlled hemp dogbane slightly longer. Thiocarbamate herbicides inhibited deposition of epicuticular wax on the leaves of hemp dogbane in 1977 but not in 1978. It appears that preplant applications of the thiocarbamate herbicides may aid in controlling hemp dogbane via delayed emergence, reduced plant vigor, and possibly greater adsorption of 2,4‐D applied subsequently as a foliar application.
Shoot and Root Growth of Wheat Seedlings Exposed to Several Levels of Matric Potential and NaCl‐Induced Osmotic Potential of Soil Water1
Authors: Sepaskhah A. R. , Boersma L.
Published: July 2010

In saline media the osmotic potentials are often of the same magnitude as the matric potential. Thus their interaction effects on plant growth are important. This study was conducted to determine the interaction effects of osmotic potentials of soil water induced by NaCl (0, −4, −8, and −12 bars) and matric potentials induced by Carbowax 4000 (−0.3, −2.5, −5.0, and −7.5 bars) on the shoot and root growth and root elongation rate of 2‐week‐old wheat seedlings (Triticum aestivum L.) in a walk‐in growth room. Seedlings of spring wheat, ‘Fielder’, were grown in a Xerollic Durargids loam soil separated from the surrounding nutrient solution by a semipermeable, cellulose‐acetate membrane. Leaf water potential was measured with a pressure chamber apparatus. Root length was estimated by line‐intersection counting of stained root segments during microscopic examination. Plant growth was measured by the determination of dry weights of shoots and roots at the beginning and end of an 11‐day experimental period. Growth was more reduced by decreases in matric potential than by decreases in the osmotic potential. A greater interaction between the effects of the osmotic potential of the soil water and the soil matric potential occurred with shoot growth than with root growth. The 50% reduction, Y50, occurred at osmotic potentials of the soil water ranging from −6.8 to −8.8 bars for shoot growth and at potentials ranging from −6.8 to −8.4 bars for root growth at the soil matric potentials ranging from −0.3 to −7.5 bars, respectively. Shoot growth showed lower tolerance to the decreasing osmotic potentials at soil matric potentials less than −2.5 bars. The Y50 values of potential were −8.6 and −5.4 bars for NaCl‐induced (osmotic) and Carbowax induced (matric) potentials, respectively. Shoot growth ceased at the leaf water potentials of −19.7and −15.3 bars at the NaCl and Carbowax‐induced potentials, respectively. Decrease in root density occurred at the soil matric potentials lower than −5.0 bars while it was reduced at all the experimental levels of osmotic potential. Root elongation rates ceased at matric potentials of −11, −12, −12, and −7 bars at osmotic potentials of 0, −4, −8, and −12 bars. respectively. Osmotic adjustment in the plant cells and possible toxic effects of Na and Cl ions or ionic imbalances on shoot growth and root elongation have been discussed.
Effect of Exchangeable Sodium on the Yield and Chemical Composition of Raya (Brassica juncea L.)1
Authors: Singh S. B. , Chhabra R. , Abrol I. P.
Published: July 2010

Large sodic areas of India are being brought under cultivation using gypsum as an amendment and by appropriate agronomic practices. Raya (Brassica juncea L.) is an important oilseed crop of the area, but virtually nothing is known about its tolerance to exchangeable Na. This study examined the effect of varying the exchangeable Na percentage on the yield and chemical composition of raya that was cultivated in the field. Raya was grown on plots that had been treated with graded doses of gypsum and subsequently cropped. At the time of planting, the soils (Aquic Natrustalfs) had attained ESP's of from 2.6 to 50.6 in the 0 to 15 cm layer and 20 to 90 in the 15 to 30 cm layer. Plant samples were analyzed and the oil content of seeds was estimated. Soil was analyzed for exchangeable Na and other chemicals. We found out that an ESP of more than 23 delayed germination, emergence of flowers and pods, but enhanced maturity. Grain and oil yield were significantly reduced above an ESP of 23.

The decrease in the grain yield was associated with a Na content of 0.28% and a Ca:Na and K:Na of 3 in the stem at maturity. Sodium increased and Ca decreased with an increase in ESP; there was no effect on P and Mg content of the different plant parts. Potassium content at early stages of plant growth decreased with increase in ESP but was unaffected at maturity. Increasing soil ESP, in the range studied, did not affect the Fe, Mn, Zn, and Cu content of different plant parts.
Effect of Exchangeable Sodium on the Rate and Pattern of Water Uptake by Raya (Brassica juncea L.) in the Field1
Authors: Acharya C. L. , Sandhu S. S. , Abrol I. P.
Published: July 2010

Sodium can adversely affect crop growth, and the mechanism by which roots obtain water in sodic soils needs further study. Effect of exchangeable Na (ES) on the rate and pattern of water withdrawal by roots of irrigated raya (Brassica juncea L.) was studied in aquic Natrustalfs soils in a field experiment. Root water extraction was measured by monitoring the change in water content and the flux divergence with time in the soil profile. Flux divergence was calculated from the knowledge of the hydraulic conductivity vs. water content relations established in the field for different percent of ES soils and the hydraulic gradients obtained in situ during crop growth. Both the rate (Rz) and pattern of water withdrawal from the soil profile by the roots were significantly affected by the amount of Na in the surface and subsurface layers. The Rz measured in soil having ES of 38% in the 0 to 15 cm layer was 0.141 cm day‐1 compared to 0.233 cm day−1 in soil with ES of 4%. In high ES soil 78% of Rz came from the 0 to 15 cm layer and the layers below 30 cm did not show any change in water content. In low ES soil 0 to 15 and 15 to 30 cm layers contributed about 77% of the total Rz and water extraction by the roots was apparent to the 60 cm depth.
Response of Kleingrass and Buffelgrass to Herbicides1
Authors: Bovey R. W. , Baur J. R. , Merkle M. G. , Bashaw E. C.
Published: July 2010

Kleingrass and buffelgrass are sometimes difficult to establish in the field from seeding because of poor seedling vigor and severe competition from weeds. Greenhouse studies were conducted to evaluate the tolerance of kleingrass (Panicum coloratum L. ‘Selection 75’) and buffelgrass (Cenchrus ciliaris L. ‘Nueces’) seedlings to nine herbicides applied pre and postemergence at rates of 0, 0.28, 0.56, 1.12, and 2.24 kg/ha. Herbicides investigated were atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine], ametryn [2‐(ethylamino)‐4‐(isopropylamino)‐6‐(methylthio)‐s‐triarine], prometryn [2,4‐bis(isopropylamino)‐6‐(methylthio)‐s‐triazine], and propazine [2‐chloro‐4,6‐bis(isopropylamino)‐s‐triazine]; linuron [3‐(3,4‐dichlorophenyl)‐l‐methoxy‐l‐methylurea], pendimethalin [N‐(lethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine], alachlor [2‐chloro‐2',6'‐diethyl‐N‐(methoxymethyl)acetanilide], metolachlor [2‐chloro‐N(2‐ethyl‐6‐methylphenyl)‐N‐(2‐methoxy‐l‐methylethyl)acetamide], and propachlor [2‐chloro‐N‐isopropylacetanilide].

Kleingrass and buffelgrass were grown in a 1:1:1 Houston black clay (Udic Pellustert): sand: peat moss mixture in small pots. Five to 10 plants were typically grown in each pot with five replications (pots) per treatment. All herbicides were sprayed in water at a spray volume of 93.5 L/ha. Herbicide injury counts were made by visually estimating percent desiccation and/or dead plants per pot 14 days after treatment.

Kleingrass seedlings were tolerant to preemergence sprays of propazine up to and including 0.56 kg/ha. All other herbicides and rates applied preemergence were phytotoxic to emerging kleingrass. At the early postemergence stage, kleingrass tolerated rates up to and including 2.24, 0.56 and 0.28 kg/ha of propazine, propachlor and metolachlor, respectively, but did not tolerate other herbicides included in the study. Response of buffelgrass to pre and postemergence applications of propazine was similar to kleingrass. Buffelgrass, however, tolerated early postemergence sprays of propachlor and atrazine at 0.28 and 0.56 kg/ha; pendimethalin and alachlor at 1.12 kg/ha each; and metolachlor at 2.24 kg/ha. Propazine was the only herbicide that showed promise for both preemergence and postemergence applications in kleingrass and buffelgrass.
Extractant Color as a Factor in Grain Sorghum Tannin Analysis1
Authors: El Tuhami M. K. , Cummins D. G. , Burns R. E.
Published: July 2010

Methods of tannin analysis for sorghum [Sorghum bicolor (L.) Moench] depending on color reaction, such as vanillin hydrochloric acid (VHCl) and modified vanillin hydrochloric acid (MVHCl), have not accounted for the color of the extract due to various pigments before adding the test reagents. The objective of this study was to determine how much this original color intensity affects the apparent level of tannin in the plant material. Tannin in the extract was estimated by the traditional VHCl method. The original color of the extract (without reagents) was measured after adding methanol to the extractant and using methanol as 100% transmittance standard. The amount of tannin in the grain, milk, dough, and mature stages of 20 single cross sorghum hybrids was estimated. Results from the VHCl method compared to correction for extractant color showed that the original color of the extractant before adding the reagents for color development had a significant effect on the measured tannin levels. The amount of tannin measured after correcting for extractant color was significantly lower than that measured by VHCl. The corrected method showed that the amount of unmeasured pigments differed with maturity, location, hybrid, and year. The corrected method produced lower standard errors and coefficients of variation than the VHCl method, and the corrected method probably produced the most accurate estimation of astringent tannins.
Tolerance of Soybean Genotypes to Metribuzin1
Authors: Eastin E. F. , Sij J. W. , Craigmiles J. P.
Published: July 2010

Metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐5(4H)‐one] controls several troublesome weeds in soybean [Glycine max (L.) Merr.], but may result in excessive soybean injury. Previous research has shown differential soybean cultivar responses to metribuzin. Sixteen determinate soybean genotypes, including the new cultivar ‘Dowling,’ and several genotypes whose tolerance have not been reported previously, were evaluated in a greenhouse for their response to 0.3, 0.6, and 1.1 kg/ha metribuzin applied preplant incorporated. Ts 72‐6, ‘Forrest,’ ‘Davis,’ ‘Hutton,’ Dowling, ‘McNair 800,’ and Ts 74‐23, were moderately tolerant; ‘Dare,’ PI 200492, ‘Pickett 71,’ ‘Bossier,’ and ‘Ransom,’ were moderately sensitive; and ‘Semmes,’ ‘Hampton 266A,’ ‘Tracy,’ and Ts 74‐34, were sensitive to the use rate of 0.6 kg/ha when evaluated 2 weeks after planting. Increased rates of metribuzin resulted in increased injury within a given genotype. Metribuzin should not be used for weed control when sensitive cultivars are being grown.
Effect of Rowspacing on Yield of Spring Planted Austrian Winter Field Pea1
Authors: Heneise H. K. , Murray G. A.
Published: July 2010

Austrian winter field peas [Pisum sativum spp. arvense (L.) Poir.] are usually planted in the fall on 18 cm row spacings. Winter damage, cold soils, and soil‐borne diseases reduce vigor of fall planted peas more than spring planted peas. Spring planted peas escape winter damage and cold soil problems and have more resistance to some of the soil borne diseases. This study was undertaken at two locations to determine the influence of row spacings on yield of spring planted Austrian winter field pea. Row spacings were 18 cm between rows, 36 cm between rows, and alternating spacings of 18 and 36 cm between rows. ‘Fenn’ peas planted on 18 cm row spacings averaged 29 and 43% more seed than peas planted on 18‐36‐18 and 36 cm row spacings, respectively. Weed competition did not significantly influence seed yield of spring planted Fenn peas at any row spacing or location. Vine dry weight of peas planted on 18 cm rowspacings at mid‐season and harvest was significantly higher than vine dry weight of peas planted at other rowspacings, regardless of weed control treatments. Vine dry weight at harvest was also highest for peas that had been weeded regardless of rowspacing. Spring planted Austrian winter peas yielded about one‐third to one‐half as much as fall planted winter peas in independent studies.
Soybean Response to Indigenous Rhizobia as Influenced by Cultivar Origin1
Authors: Nangju D.
Published: July 2010

Many investigators believe that when grown for the first time, the soybean [Glycine max (L.) Merr.] nodulates poorly unless inoculated with Rhizobium japonicum. However, in Nigeria the cultivar ‘Malayan,’ which originated from Indonesia, has nodulated quite well with indigenous strains of Rhizobium. We chose cultivars originating from Southeast Asia and from the USA and compared parameters associated with effective nodulation when these cultivars were grown with and without inoculation with Rhizobium japonicum. Seed inoculation with Nitragin‐S inoculant did not significantly improve nodulation, growth, amino‐N stem exudate, and yield of the Southeast Asian cultivars Malayan, ‘Orba,’ and ‘TGm 686.’ In contrast, the American cultivars ‘TGm 294‐4‐2371,’ ‘Bossier,’ and ‘Jupiter’ nodulated poorly without inoculum, and showed increases in growth of 36 to 47% and seed yield of 40 to 97% when inoculated. However, the American cultivars generally have better agronomic characteristicsa and higher yield potential than the Southeast Asian cultivars. It is, therefore, important to combine the desirable characteristics of these two distinct groups of soybean cultivars in the breeding program to develop improved cultivars suitable for and adapted to tropical environments.
Iron Use Efficiency in Grain Sorghum Hybrids and Parental Lines1
Authors: Esty James C. , Onken Arthur B. , Hossner L. R. , Matheson Richard
Published: July 2010

Grain sorghum [Sorghum bicolor (L.) Moench] response to iron stress appears to be somewhat different from other species (e.g. release of less reductant and fewer H+ ions into solution), and, while it is apparently genetically controlled as in other species, it may not be as simply inherited. In this study, three grain sorghum hybrids and their parental lines were screened in nutrient culture in order to make preliminary assessment of heritability of Fe use efficiency, to evaluate the screening technique and to investigate the relationship of P and Fe accumulations to Fe use efficiency in these hybrids and parental lines. The seedlings were grown in a greenhouse on a complete nutrient solution at pH 6.5 until the plants were sufficiently large for experimental use. Subsequently, they were transferred for 7 days to either a modified Hoagland‘s No. 1 or Steinberg‘s solution with Fe, P, ammonium, and nitrate concentrations being varied. The plants were visually ranked for Fe use efficiency based on Fe deficiency symptoms, P and Fe concentrations in the top two leaves were determined and the pH of the nutrient solutions was monitored.

Results obtained from screening the sorghum parental lies and F, hybrids indicated varying degrees of Fe use efficiency. Hybrid ATx 378 X RTx 2536 was classed most efficient in Fe utilization and RTx 7000 was classed most inefficient. Heterosis for Fe efficiency was observed when line ATx 378 was combined with lines RTx 2536, RTx 7000 and RTx 415. However, the efficiency of the two latter hybrids was not as good as ATx 378 X RTx 2536. Parental line RTx 2536 had a higher Fe efficiency ranking than the other three restorer lines. The inheritance of the Fe efficient trait appears to be dominant or over‐dominant in nature. Chemical analyses in this work, show that a negative, apparently linear, correlation exists between P and Fe concentrations in the top leaves of the sorghums studied.
A Weighing Lysimeter for Use in Isolated Field Areas1
Authors: Heatherly Larry G. , McMichael B. L. , Ginn L. H.
Published: July 2010

A weighing lysimeter was designed for and used in field areas not equipped to accommodate instrumentation requiring a power supply or constant maintenance for accurate operation. A hanging crane scale, which held the lysimeter box, remained responsive and accurate throughout a season of field installation. The only maintenance requirement was that of periodically leveling the suspended box by adjusting turnbuckles installed at each corner. Seasonal water loss data were obtained from lysimeters planted with cotton (Gossypium hirsutum L.) and soybeans [Glycine max (L.) Merr.]. These data are comparable to other lysimeter water use data for these two crops obtained at other locations.
Close‐Grown Tobacco: Yield, Alkaloids, and Sugar Content by Stalk Position1
Authors: Campbell C. R. , Chaplin J. F. , Johnson W. H. , Miner G. S.
Published: July 2010

Flue‐cured tobacco (Nicotiana tabacum L.) produced in a close‐grown system may offer an alternative to use of synthetic smoking materials. In order to develop optimum production and handling practices for this system, information is needed on the chemical and physical contents of the harvested material.

Tobacco (‘Sp C‐28’) was produced in a close‐grown system with varying plant populations (45,448, 90,896, 136,344 plants/ha), N‐rates (84, 168, 252, 336 kg/ha), top ping (topped vs. nontopped), and row spacings (equidistant vs. twin). The research was conducted at the Oxford Tobacco Research Station on a Durham loamy sand (fine loamy, siliceous, thermic, Typic Hapudult). Yield, total alkaloids, and reducing sugars of lamina, midrib, and stalk from the upper, middle, and lower thirds of cured plants were compared.

One‐third of the total plant weight was in each stalk position. The upper third of the close‐grown plant contributed most to total lamina weight and total alkaloid level. The proportion of lamina in the upper stalk position was higher in plants that were topped or when plant population was increased above 45,448/ha but it deoreased when N‐rate was increased above 84 kg/ha. Total alkaloid concentration was highest in the upper stalk position and in lamina. Increased plant population resulted in decreased total alkaloids in the middle stalk position. Topping and increasing N‐rate resulted in higher total alkaloids in all stalk positions. Reducing sugar content was approximately the same for all three stalk positions but highest levels in lamina and midrib were found in the upper two‐thirds of the plant. Reducing sugar concentrations were highest in stalk. Plant population had no significant effect on reducing sugar content but increased N‐rate lowered concentrations in the lower stalk position.

Results indicate that agronomic practices offer a means for altering the physical and chemical content of closegrown tobacco.
Irrigation Regime and Honeybee Activity as Related to Seed Yield in Alfalfa1
Authors: Goldman A. , Dovrat A.
Published: July 2010

Seed yields of alfalfa (Medicago sativa L.) vary capriciously in time and space. This variation seems mainly caused by the delicate interplay between plant factors monitored by soil moisture availability and the obligate tripping requirement of alfalfa flowers by pollinators. The object of this study was to quantify the main effects and interactions between water application to the alfalfa field and tripping by honeybees, to identify mechanisms which affect the seed yield and to suggest indices for their quantitative evaluation. A wide array of conditions differing in soil moisture and in tripping level was established in the sprinkler‐irrigated field. Observations were made on flowering and pod set of the plants and on the pollinating behavior of the bees.

High water rates decreased seed yield. A moderate rate, applied at mid‐flowering to a relatively dry soil, markedly increased seed yield; the effect diminished toward the beginning of the end of flowering. The effect of water application depended also on the degree of tripping.

The tripping pressure of honeybees (ie., their propensity to trip alfalfa flowers) was found to be inconsistent and seems to depend mainly on the availability of competing pollen sources. Dry and wet plots were equally welltripped under high tripping pressure and were neglected under low tripping pressure. Under moderate tripping pressure, pollen bees were attracted to dry plots earlier in the morning and in greater numbers than to wet plots, resulting in a higher percentage of tripped flowers, but the total number of tripped flowers was higher in the wet plots.

Death of stem apices and a decrease in the rate of node formation were identified as mechanisms which regulate the duration and intensity of flowering and pod set.
Dinitrogen Fixation (C2H2) by Established Forage Grasses in Texas1
Authors: Weaver R. W. , Wright Sara F. , Varanka M. W. , Smith O. E. , Holt E. C.
Published: July 2010

Efficient forage production by grasses requires an input of fertilizer nitrogen. Fertilizer N applications substantially increase the cost of forage production. Development and management of a biological N fixation system for forage grasses would greatly increase forage production efficiency. As a first step toward development of such a system, a survey was undertaken in the subtropical region of Texas to determine the rates of biological N fixation naturally occurring in the rhizosphere of native and introduced forage grasses. The acetylene reduction method was used to estimate potential rates of biological N fixation. During 3 years, 463 soil cores were collected, of which 13% produced ethylene when exposed to acetylene. In the third year of the survey, 216 cores were collected, of which 21% reduced acetylene to ethylene when tested immediately after sampling, and 70% showed activity after a period of regrowth in the greenhouse. Only samples extrapolated to fix N at rates exceeding 0.5 kg/ha/100 days were classified as active. The most active rhizosphere samples were extrapolated to fix N at rates of 33, 26, 20, and 20 kg/ha/100 days for Cynodon dactylon (L.) Pers., Paspalum urvillei Steud., Brachiaria sp., and Andropon gerardi Vitman respectively. These high rates indicate that under the proper environmental conditions a potential exists for agronomically significant rates of biological N fixation to occur in the rhizosphere of forage grasses.
Defoliation Effects on Regrowth, Nodulation, and Nitrogenase Activity at Anthesis with Hairy Vetch1
Authors: Lynd J. Q. , McNew Ronald W. , Odell George V.
Published: July 2010

Pasture legumes present a great potential to increase productivity of pastures. Little information is now available concerning quantitative evaluation of symbiotic N fixation with pasture legumes such as hairy vetch (Vicia villosa, Roth).

Results from 3 years of study are summarized to determine the influence of defoliation and regrowth on tillering, nodulation, and nitrogenase activity (C2H2 reduction) at anthesis with ‘Madison’ hairy vetch inoculated with Rhizobium legumimsarum Frank, ATCC 10314. Plants were grown in a siliceous thermic Psammentic Paleustalf (Eufaula) of pH 6.1. Peak nitrogenase activity of field grown plants occurred at anthesis about 250 days after emergence. Highly significant increases in tillering resulted with three defoliations at 45, 90, and 180 days along with increased nodule fresh weight, nodule numbers, and nitrogenase levels. Abundant large cluster nodule types occurred on root systems of most plants regardless of defoliation treatment. Significant correlations were apparent for nitrogenase levels with top weight, number of tillers, nodule weight, and number of nodules for plants receiving the threedefoliation treatment. Nodule number was significantly correlated with top weight. Nodule number and nodule weight were negatively related probably due to an influence from frequent large nodule cluster development. No significant correlations were apparent with the nondefoliated plants. Multiple regressions indicated nitrogenase levels were influenced in decreasing order by nodule weight, tillers, top weight, and nodule number with R2 = 0.775, C.V. = 29.1% P < 0.001. The pot culture technique used may be adapted for nondestructive evaluations with repotted plants utilized for plant breeding and further symbiotic N fixation research.
Reflectance of Wheat Cultivars as Related to Physiological Growth Stages1
Authors: Leamer R . W. , Noriega J. R. , Gerbermann A. H.
Published: July 2010

Crop yield predictions are based on a comparison between the rate of growth of the current crop and the normal crop‐calendar. Remotely sensed reflectance data provide an indication of the amount of plant growth. In this investigation, we followed the seasonal changes in reflectance of three cultivars of wheat (Triticum aestivum L.) as related to their physiological development. Reflectances over the 0.45 to 2.50‐µ/m wavelength intervals were measured with a ground‐based spectroradiometer between planting and maturity of wheats planted on Hidalgo sandy clay loam (Typic Calciustolls) soil in south Texas. After plants covered about 25% of the ground area, all reflectance curves had the characteristic shape for vegetated surfaces. Wheat plants seldom reach the eight leaf layers required for infinite reflectance in the near‐infrared plateau (0.75 to 1.35 µ/m) wavelengths. Consequently, reflectance at these wavelengths were closely related to stage of physiological development as long as the plants were developing leaves, regardless of their rate of maturity. Dwarf, early Mexican cultivars (‘Anza’ and ‘Penjamo’) that were not daylength‐sensitive progressed through physiological stages more rapidly than did a tall, later maturing, daylength‐dependent cultivar (‘Nadadores’). Reflectance in the near‐infrared plateau increased as plants of all cultivars developed physiologically until they reached Feekes growth Stage 9. Growth Stage 9 represents the stage at which the last ligule has appeared and the plant goes into the booting stage. The lower leaves began to turn brown, lose chlorophyll, and mature, resulting in a decrease in the number of actively reflecting leaf layers with a consequent decrease in reflectance within the near‐infrared plateau wavelengths. Reflectance at other wavelength bands are not sensitive to the stage of physiological growth. Knowledge of the stage of plant development through a crop season will improve the accuracy of yield predictions made prior to harvest.
Use of the Third Youngest Leaf to Estimate Leaf Area in Kentucky Bluegrass1
Authors: Eggens J. L
Published: July 2010

Periodic, non−destructive data on the number of leaves, tillers, and emerged rhizomes are basic to the determination of turfgrass response to stress. Although the leaf area of turfgrasses is also markedly affected by stress, it is difficult and time−consuming to obtain without injury to the herbage.

To determine if the leaf measurements of a specific leaf of each plant is correlated to the same leaf measurements for all leaves of that plant, leaf measurements were made on all leaves of individual Kentucky bluegrass (Poa pratensis L.) plants subject to stress treatments of a restricted root zone, competition from plants of a different cultivar, and 4 cm mowing height. The plants were grown in vermiculite in plastic pots. Two experiments were conducted in the greenhouse while a third was conducted in a growth chamber. Leaf length measurements involving the sheath were taken from the crown while lamina length measurements were taken from the junction of the leaf blade and the leaf sheath. Blade width measurements were made midway along the lamina length for unmowed grasses and 1 cm from the junction of the leaf blade and leaf sheath for grasses mowed at 4 cm.

The correlation coefficients for the leaf (sheath and blade) length (r ≥ 0.86), blade length (r ≥ 0.86), and blade width (r ≥ 0.92) of the third youngest leaf and the same measurements for the total leaf length of each shoot of ‘Birka’, ,‘Nugget’, ‘Sydsport’, and ‘Touchdown‘ were found to be highly significant. The γ values were highly significant. when the same measurements were made on Touchdown plants regularly mowed at 4 cm and on unmowed Nugget plants growing in competition with ‘A−34’ Kentucky bluegrass.

Leaf measurements of the third youngest leaf can be used to estimate growth responses of Kentucky bluegrass plants which result in changes in leaf area. Blade measurements of intact turfgrass plants in a sward are useful to estimate changes in leaf area as they are easily obtained and result in little injury to the herbage.
Testing the Difference between Limiting Yields in Quadratic Fertilizer Response Curves1
Authors: Tejeda Hernan R.
Published: July 2010

Knowledge on whether or not fertilizer respom curves have the same limiting yield is useful when comparing fertilizers and estimating their availability coefficient. A statistical procedure to test the difference between limiting yields of two quadratic response curves is presented. The test is contingent to the assumption that the estimated nutrient rates corresponding to the limiting yields are constants. Application of the procedure is illustrated when comparing rice (Oryza sativa L.) response to two sulfur‐coated ureas (SCUs) differing in solubility with split application of urea. Only the SCU with lower solubility produced a significantly larger limiting yield than split application of urea.
Reproduction of Peanuts Treated with a Cytokinin‐Containing Preparation1
Authors: Ketring D. L. , Schubert A. M.
Published: July 2010

Cytokinins are a major class of plant hormones that regulate plant growth and development. They promote cell division, delay leaf senescence, and maintain protein and chlorophyll levels in detached leaves. Cytokinin activity is high during early stages of fruit and seed development. Thus, they offer a possible means to enhance reproduction of peanuts (Arachis hypogaea L.). Cytex3 is a water‐soluble plant (algae) extract containing about 100 ppm kinetin equivalents by bioassay. Cytex was applied at rates of 0.94, 1.27, 1.88, and 3.76 ml of formulation per ma of ground area in three soil types in the field. Treatment times were: (I) early flowering stage (35 to 40 days after planting), (II) late flowering‐pegging stage (59 to 61 days after planting), and (111) both stages (I) and (II). In the initial test in 1976, 1.27 ml Cytex/m2 was applied to ‘Florunner’, ‘Starr’, and ‘Tamnut 74‘ at all treatment times. Some treatments tended to produce more kg pod/ha than the check, but there were no significant differences in yield or value. In 1977, a significant increase in yield of Tamnut 74 occurred at the 3.76 ml Cytex/m2 rate applied at Treatment time (III). In this test, the plants were sprinkler irrigated about 24 hours after spraying. This treatment‐irrigation procedure was used in 1978 to test three rates (0.94, 1.88, and 3.76 ml Cytex/m2) on reproduction of Florunner and Tamnut 74. There were no significant differences among treatments and check for yield, grade, and value of the peanuts produced. Thus far, we have been unable to obtain consistent and significant effects on reproduction of peanuts with foliar Cytex sprays.
Oxygen Uptake by Corn Roots in Flowing and Stirred Solution Cultures1
Authors: Zandstra‐Blom M. , Ben‐Asher J. , Gale J.
Published: July 2010

A model incorporating the mechanism of the O2 uptake process as described by the Hill equation and mass flow mechanisms is given for both steady‐state and time‐dependent cases. The two versions of the model were used to study O2 uptake. Computed results of the steady‐state model indicated that the higher the water flux density the less O2 depletion there was in relation to distance from the aeration point. The hypothesis raised by these theoretical results is that availability of O2 in aqueous media may be influenced by water flux density. The objectives of this research were therefore to test the above hypothesis experimentally and to compare measured and calculated results with the time‐dependent model. The experiments were based on a hydroponic system with corn plants (Zea mays, ‘Jubilee’) placed on flowing plates. At a certain point air was pumped continuously. Measurements of O2 concentration as a function of distance from this point were taken at various velocities. The test of the second model was made in a container with a stirred‐solution culture. Calculated and experimental results for the steady‐state model agreed with each other and suggested that the flow rate of the solution is an important factor in controlling O2 concentration along the channels. For a homogenous solution (i.e., O2 concentration which is not affected by the distance from the aerated point), the time‐dependent version of this model gave satisfactory results when compared to measured values on a quantitative basis. Qualitatively, however, the agreement was not so good.
Simulating Yield Losses in Grain Sorghum due to Sorghum Downy Mildew1
Authors: Tuleen D. M. , Frederiksen R. A.
Published: July 2010

Reliable estimates of potential losses to disease enable growers to profitably manage crops. Simulation models can give unbiased loss estimates as well as determine research areas critical to the understanding of host‐parasite interactions.

A model is presented for calculating yield loss in grain sorghum [Sorghum bicolor (L.) Moench] due to systemic sorghum downy mildew caused by Peronosclerospora sorghi (Weston & Uppal) Shaw. It is sensitive to plant population, disease reaction of the hybrid, and rainfall following planting. The model was developed using data sets from field experiments conducted over several years in South and Central Texas. Empirical data indicate that: 1) a low incidence of systemic infection can thin dense sorghum stands to an optimum plant density and allow healthy plants to prosper, 2) genetic resistance effectively reduces grain yield losses caused by the disease, and 3) rainfall within 4 to 7 days after planting is associated with a low incidence of sorghum downy mildew at the locations observed. Model estimates were plotted against measured crop yields using seven data sets (from field tests conducted in 1975 and 1979 at two South Texas locations). Multiple regression analysis performed on the data showed that the model simulated grain yield with acceptable precision.
Papermill Lime‐Sludge as an Alternative Liming Material1
Authors: Simson C. R. , Kelling K. A. , Liegel E. A.
Published: July 2010

Calcitic papermill lime‐sludge, a by‐product of the kraft paper process, was evaluated as a liming material and its equivalency with dolomitic agricultural limestone determined. An incubation study involving 10 medium‐ or light‐textured Wisconsin soils demonstrated that lime‐sludge neutralizes soil acidity very rapidly. Maximum soil pH was achieved in less than 1 week after application of the lime‐sludge, while the pH of soils treated with finely‐ground agricultural limestone increased continuously throughout the 24‐week incubation period.

In field trials conducted for 3 years on two different soils, corn (Zea mays L.) was followed by alfalfa (Medicago sativa L.) or birdsfoot trefoil (Lotus corniculatus L.). Both legumes responded favorably to liming but not differently to the lime‐sludge and agricultural limestone, whereas a response was not observed for corn. Yield data provided no evidence that use of the calcitic lime‐sludge created Mg stress in any tested crop. Plant tissue analyses and the absence of a yield response to soil‐applied MgSO4•7H2O supported this observation.

The liming equivalency of lime‐sludge to agricultural limestone was examined under both laboratory and field conditions. Both suggested that 1 m3 of the lime‐sludge has the same liming value as 1.1 metric tons of agricultural limestone with a neutralizing index of 60 to 69. This value is considerably less than the equivalency of 1.5 yd.3 of lime‐sludge per ton of 60 to 69 agricultural limestone specified by Wisconsin Administrative Code.
Table Beet Responses to Residual and Band‐applied Phosphorus and Potassium1
Authors: Peck N. H. , MacDonald G. E.
Published: July 2010

Many soils used for vegetable production have been heavily fertilized and, therefore, have accumulated large amounts of available P and medium amounts of available K. Fertilizer P and K applications should be adjusted to obtain the optimum plant response to residual soil P and K. Table beet plants (Beta vulgaris L.) were grown in a Honeoye fine sandy loam soil (Glossoboric Hapludalf, fine, loamy, mixed mesic) with 3 to 162 kg residual available soil P and 84 to 908 kg residual available soil K kg/ha (0 to 25 cm depth), as measured in an ammonium acetate‐acetic acid extraction solution buffered at pH 4.8. A factorial combination of banded P as concentrated superphosphate (CSP) at 0 and 70 kg P/ha, and banded K as potassium chloride (KCl) and potassium sulfate (K2SO4) at 0 and 140 kg K/ha were randomized in each of the residual soil P and K levels.

Both residual soil P and K, and banded fertilizer P and K increased the root yields. Positive yield responses to soil P and K were greater than to banded P and K.

There was no difference in yield between banded applications of KCl or K2SO4. The two fertilizer sources of K fertilizer changed the concentrations of some of the elements, especially Cl, S, and Mn, in leaf blades.

Soil P and banded P, especially with low soil K and without banded K, increased the concentration of P in the leaf blades, while soil K and banded K decreased the concentration of P in the leaf blades. Soil K and banded K increased the concentration of K in leaf blades while soil P and banded P decreased the concentration of K in the leaf blades. The concentration of K in leaf blades at midseason, especially in plants grown with banded P, was a good predictor of yield of roots at harvest.
A Container for Studies of Root Response to Soil‐Air Composition1
Authors: Koenig P. G. , Teague W. R.
Published: July 2010

Studies of root response to soil‐air composition often require containers capable of isolating the root system, but not the above ground plant parts from the atmosphere. Small containers for growing plants in the atmosphere while controlling the gas composition of soil and roots were constructed from plexiglass tubing. A description of the design and methodology associated with their use is presented in this paper. Their small size allows a large number of containers to be used where space is limited and keeps gas supply requirements at low levels. The system is shown to be capable of maintaining a constant gas composition over periods of several days.
Determining the Legume‐Fraction of a Grass‐Legume Mixture by Pinitol Analysis1
Authors: Smith A. E.
Published: July 2010

The majority of the methods, presently used for determining the botanical composition of mixed forages, are complicated, time consuming, and seldom accurate. The increasing interest in research on grass/legume forage mixtures gives rise to the need for accurately surveying the botanical composition available to the grazing animals. The purpose of this report is to describe a simple, accurate, and rapid method for determining the legume foliage composition in a grasslegume mixture. Pinitol (l‐D‐3‐0‐methyl‐chiro‐inositol) was isolated from forage legumes, grown in the greenhouse and field plots, and determined to be unique to the Leguminosae family. Since pinitol occurs only in the legume fraction of a grass‐legume forage mixture, the legume composition is directly proportional to the pinitol concentration in the 80% ethanolic extract of the dried ground foliage mixture. Contrary to carbohydrates, pinitol concentration in legume foliage has been determined to be relatively stable over a normal daily range of environmental conditions and each stage of plant growth. The procedure was evaluated by determining the alfalfa (Medicago sativa L.) component of a greenhouse grown alfalfa‐fescue (Festuca arundinacea Schreb.) mixture over a range of concentrations and found to accurately estimate the actual legume composition (r2 = 0.989). This method could be easily adapted for use in quantifying the legume composition in animal diets collected by esophageal fistulated animals.
Effect of N Fertilizer and Corn Residue Management on Organic Matter in Minnesota Mollisols1
Authors: Bloom P. R. , Schuh W. M. , Malzer G. L. , Nelson W. W. , Evans S. D.
Published: July 2010

Two long‐term continuous corn (Zea mays L.) experiments were used to determine the effect of the rate of stover return on soil organic matter in high organic matter mollisols (O.C. > 2.4%). One experiment was an N rate experiment which had been cropped for 19 years. The other was a stover‐fertility management study which had been cropped for 13 years in which there were two stover management treatments: total removal and plowdown, both at high and low fertility. In the N rate experiment a 3‐ton ha−1 yr−1 difference in stover yield between the low and high N rates resulted in a 4.5% less organic carbon content for the lower N rate after 19 years. All of the treatments in the stover management study had no significant changes in organic matter content after 13 years except for the low fertility‐stover removal treatment which had 15% less organic carbon. It was concluded that for precise estimates of treatment effects on organic carbon loss in mollisols, longer treatment times are needed.
Foliar Fertilization of Dry Beans with Zn and NPKS1
Authors: Lauer D. A.
Published: July 2010

In response to increasing grower use of foliar fertilization, field experiments were conducted from 1977 through 1979 to evaluate the effects of Zn and NPKS foliar fertilization of dry beans (Phaseolus vulgaris L.) on nutrient concentrations in the tissue and on yield.

Commercial Zn formulations of ZnSO4, ZnEDTA (Zn ethylenediamine tetraacetate), NZn and ZnPK were sprayed at growth stages ranging from early vegetative (V4) to early bloom (R1). Foliar NPKS was applied at growth stages ranging from full bloom (R2) to fully expanded seed (R7). Foliar Zn and NPKS were applied either separately or together in combination treatments.

Throughout the study there was no yield increase from foliar‐applied Zn when soil Zn was adequate. There was a yield increase over the untreated check in 1978 but not in 1979. No consistent differences in bean yields were observed among ZnSO4, ZnEDTA, NZn, or ZnKP. Stage of growth at which the foliar fertilization was applied did not affect yield response.

All foliar Zn treatments increased plant tissue Zn except at growth stage V4 which had insufficient foliage to intercept the spray. Similar tissue Zn cone resulted from foliar ZnSO4, ZnEDTA, and ZnKP. The NZn material, containing Zn dissolved in a solution of urea, ammonium, and nitrate N, consistently resulted in about twofold greater tissue Zn than the other Zn materials.

Concentrations of N, P, K, and Zn in the bean seed were not consistently affected by foliar applications of Zn or NPKS. Even twofold to fourfold differences in whole plant Zn cone did not affect seed Zn cone.
Interrelationships of Irrigation Frequency, Urea Nitrogen, and Gypsum on Forage Sorghum Growth on a Saline Sodic Clay Soil1
Authors: Mustafa M. A. , Abdelmagid E. A.
Published: July 2010

Two field experiments were conducted in June, 1978, and April, 1979, at the Khartoum University Farm, Sudan, to study the effect of irrigation frequency, urea‐nitrogen, and gypsum on the yield of forage sorghum (Sorghum vulgare L.) grown on a semi‐arid, salinesodic clay soil. Each experiment had four nitrogen levels: 0N, 1N, 2N, and 3N (1N = 43.8 kg N/ha) applied as urea; three irrigation frequencies: 7, 10, and 15 days; and zero or 11.9 tonnes/ha gypsum, each replicated thrice in a split‐split plot design. The seasonal quantity of water applied was the same for all frequencies of irrigation and was slightly higher than evaporation from a U.S. class A pan.

The two seasons data consistently showed that dry matter yield of the first cuts of forage sorghum increased significantly with increase in N‐level, with decrease in irrigation interval, and with gypsum application. Decreased irrigation frequency had greater effect than 3N fertilization. The benefits from gypsum application were low (5%) at the 7‐day irrigation interval. Dry matter yields were increased from 1.84 to 6.12 tonnes/ha in 1978 and from 3.20 to 7.23 tonnes/ha in 1979, by irrigating every 7 days instead of 15 days, application of 3N and 11.9 tonnes/ha gypsum.

Plant height and leaf area index increased with N fertilization, with gypsum and with reduction of irrigation interval from 15 to 7 days, whereas germination percentage was significantly increased by gypsum only. Dry matter yield significantly correlated (P = 0.01) with leaf area index and plant height but not with germination percentage. Multiple regression analysis showed that the first two growth attributes accounted for about 87% of the variability of yield. The dry matter yields of the second cuts were similarly affected by treatments but were about one‐half to one‐third those of the first cuts in 1978 and 1979 seasons, respectively.

For the two seasons the average seasonal water‐use was about 1.02 times that of the U.S. class A pan evaporation. Water‐use efficiency increased from 15.6 to 43.9 kg/ha‐cm in 1978 and from 19.1 to 51.2 kg/ha‐cm in 1979, by irrigating every 7 days instead of 15 days, and applying 3N urea and 11.9 tonnes/ha gypsum.