bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential Response of Sunflower Hybrids to Planting Date1
Authors: Owen D. F.
Published: July 2010

Date of planting studies are often conducted using only one cultivar as a measure of performance. When different cultivars do not respond alike to differing planting dates then results of planting date studies in which only one cultivar is used may lead to false conclusions. In an effort to determine if different sunflower (Helianthus annuus L.) hybrids responded alike to varying planting dates, five oilseed sunflower hybrids were planted at monthly intervals from late April through late July during 1977–1979 at the Texas Agric. Exp. Stn., Halfway, Texas, on a Pullman clay loam (fine, mixed thermic Torrertic Paleustoll). Major differences were found between years for yield and oleic and linoleic acid concentration, between dates for yield and concentrations of oleic and linoleic acid; and between hybrids for oil percentage. All of the interactions with years were significant. The date by hybrid interactions were not significant for yield, percent oil, and concentration of oleic and linoleic acid when averaged over years. Difference in yields among dates (α = 0.10) indicated that mid‐ to late‐July plantings produced less than late May and mid‐ to late‐June plantings. One hybrid was significantly higher in oil concentration than the others. Oleic acid concentration decreased and linoleic acid concentration increased linearly as planting dates were delayed. Planting hybrid sunflower after mid‐June as a primary crop is not recommended due to reduced yield potential and risk of frost damage. Early planting could be advantageous if higher oleic acid concentration were desired, and conversely, later planting if higher linoleic acid concentration were considered more important.
Plant Growth‐Regulating Effects of Systemic Fungicides Applied to Kentucky Bluegrass1
Authors: Kane R. T. , Smiley R. W.
Published: July 2010

Systemic fungicides applied to Kentucky bluegrass (Poa pratensis L.) turf often cause visible alterations in plant morphology. Compounds derived from 5‐pyrimidinemethanol and 1,2,4‐triazole may induce changes in color, growth rate, and density of the stand while also providing outstanding disease control. Because plant growth and stress responses contribute to the severity of many turfgrass diseases, nontarget plant growth regulating effects could influence the disease control activity of systemic fungicides. Studies were conducted to determine the effects of several systemic fungicides on Kentucky bluegrass morphology and physiology. Fungicides were compared, when possible, to growth‐regulating compounds with similar chemical and/or biological properties. Commercially available or experimental formulations were applied as soil drenches to greenhouse‐grown seedlings and as foliar sprays to field‐grown sod of ‘Merion’ and ‘Fylking’ Kentucky bluegrass. Application rates of the fungicides were as recommended for controlling Fusarium blight. Growth regulators were applied at rates comparable to the fungicides or at rates previously reported to have an effect on plant growth. Oven‐dry root weights, shoot densities (tillers plus nonemerged rhizomes), and leaf growth rates were measured. The chlorophyll content of young leaves was determined by extraction with dimethylsulfoxide. Chlorophyll retention of excised, mature leaves was measured following dark incubation. Total nonstructural carbohydrate (TNC) content in mature foliage was determined using the anthrone method. When applied to greenhouse‐grown seedlings, pyrimidinemethanol and triazole derivative fungicides reduced leaf growth rates, shoot densities, and root weights of one or both cultivars. Pyrimidinemethanols increased the chlorophyll content of Fylking and increased TNC contents of both cultivars. Triazoles also increased TNC levels while increasing chlorophyll retention of excised leaves. Chlorophyll retention was also enhanced by cytokinin analogs, including a benzimidazole fungicide. Results obtained from field experiments were inconsistent although similar growth‐regulating effects were observed following certain treatments. Our results show that the systemic fungicides studied have nontarget plant growth‐regulating activity on Kentucky bluegrass. These effects could influence the severity of stress related diseases such as Fusarium blight.
Wetting and Maturity Effects on the Yield and Quality of Legume Hay1
Authors: Collins Michael
Published: July 2010

Information is needed on the effects of rain on the magnitude of yield and quality losses of field cured legume hay. Two experiments were conducted to evaluate the influence of wetting on yield and quality losses of hay of alfalfa (Medicago sativa L.) and red clover (Trifolium pratense L.) cut at two maturity stages. Three and one‐half kilogram samples of alfalfa and red clover forage grown on Plano silt loam soil (fine‐silty, mixed, mesic Typic Argiudoll) and harvested at early and late maturity stages were placed on wire screens and allowed to dry without wetting or were exposed to natural or artificial wetting in 1980 and 1981. A completely randomized design was used with three replications in 1980 and two in 1981. In 1980, 2.5 cm of water was applied to hay wetted during drying. In 1981, hay wetted during drying was exposed to 4.1 and 6.2 cm of precipitation, respectively. Mean dry matter (DM) losses during drying in 1980 were 8.1 and 17.0% from unwetted and wetted forage, respectively, but red clover harvested at the bud stage and wetted lost 25.8% of the total DM. In 1981 unwetted forage, forage wetted during drying and forage wetted after reaching 85% DM lost 10.5, 43.4, and 53.0% of the initial DM. Wetting did not change forage N concentration greatly in either year. Forage in vitro dry matter disappearance (IVDMD) was reduced by wetting in both years. In 1981 IVDMD was reduced from 66.4% for unwetted hay to 48.1% for hay wetted during drying. Mature forage of alfalfa was lower in IVDMD than bud stage alfalfa in both years regardless of wetting treatment. Neutral detergent fiber concentration was increased by wetting red clover forage in both years. Prolonged wetting in 1981 reduced the yield of N and TNC by 40.3 and 71.5%, respectively. Dry matter and quality losses due to wetting of legume forage during hay curing vary with legume species and the timing and duration of wetting. Results indicate that plant constituents differ in their susceptibility to loss due to wetting during hay curing.
Fall Sod‐Seeding of Ladino Clover into Tall Fescue as Influenced by Time of Seeding, and Grass and Insect Suppression1
Authors: Rogers D. D. , Chamblee D. S. , Mueller J. P. , Campbell W. V.
Published: July 2010

Grass competition and insect damage may detrimentally influence establishment of forage legumes sod‐seeded into perennial grass swards. The objective of this study was to quantify and evaluate the effects of seeding date, grass suppression, and insects on fall establishment of ‘Tillman’ ladino clover (Trifolium repens L.) into tall fescue (Festuca arundinacea Schreb.) sods. Four field experiments were conducted during 3 years on a Typic Hapludult or an Ultic Hapludalf soil in the North Carolina Piedmont. Paraquat (1, 1′‐dimethyl‐4,4′‐bipyridinium ion) for sod suppression and granular carbofuran (2,3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl methylcarbamate) for insect control were not applied or were applied at 0.28 and 3.7 kg ha−1, respectively, at two seeding dates (early‐September or mid‐October) in a 23 factorial combination. Measurements were made of clover stand, insect damage, and dry matter production. Prevalent insects were identified. Much more insect damage was observed from September than from October seedings. During a 9‐day period shortly after the September seeding in Exp. 4 an 82% reduction in clover density was measured in plots not treated with insecticide. Clover establishment and 1st‐year dry matter production were often greatly increased by combining sod suppression with insect control at seeding compared with use of either practice alone. In Exp. 1 for example, seasonal yields of September‐seeded clover were 2564 and 1079 kg ha−1 for paraquat and carbofuran used alone, respectively, and 5568 kg ha−1 when used in combination. Check plots yielded 183 kg ha−1. Good winter survival was obtained from October sod seedings although the majority of clover seedlings (75 to 83%) had developed only one trifoliolate leaf by early December in three of the four trials. We conclude that the use of both an insecticide and a grass suppressant may be necessary for successful establishment of ladino clover into a tall fescue sward under some conditions and that mid‐October is a good alternative to early‐September as a seeding date during years of low moisture and high insect populations in September.
Soil Fertility and Defoliation Effects with Arrowleaf Clover and Nitrogen Fertilizer Equivalence of Crimson‐Arrowleaf Clover Combinations
Authors: Lynd J. Q. , Hanlon E. A. , Odell G. V.
Published: July 2010

Arrowleaf clover (Trifolium vesiculosumSavi) has promise as an improved forage legume that is compatible with both warm and coolseason grass species. The objective of these studies was to evaluate factors influencing the potential of ‘Yuchi’ arrowleaf clover for high forage productivity with desirable symbiotic N2fixation. Effects of soil fertility and defoliation on arrowleaf clover growth, tillering, nodulation and nitrogenase activity (C2H2reduction) were determined for a 3‐year period. Relative N2fixation as fertilizer N equivalence (FNE) was determined with a combination of arrowleaf and crimson clover (Trifolium incarnatumL.), interseeded with rye (Secale cerealeL.). Arrowleaf top growth, number of tillers, nodule mass, and nitrogenase (C2H2reduction) increased with defoliation and P, K, and Ca fertility treatments in 3 years of field experiments on a Port silt loam (fine, silty, mixed, thermic Cumulic Haplustoll). Phosphorus was the first limiting factor. Fertilizer N equivalence of arrowleaf alone was 50 kg N ha−1, with combined arrowleaf and crimson clover having an FNE of 89 kg N ha−1compared to NH4NO3fertilization for increased rye yield. Residual N fixed by the clovers increased subsequent monocultured rye yield equivalents to an FNE 111 kg N ha−1for arrowleaf clover alone and an FNE of 121 kg N ha−1for combined arrowleaf and crimson clovers.
Thatch Accumulation in Bermudagrass as Influenced by Cultural Practices1
Authors: White R. H. , Dickens Ray
Published: July 2010

Excessive thatch accumulation is a serious problem in golf course putting greens and other intensively managed turfgrass areas. More effective procedues for thatch control are needed. The relationship between different cultural practices and thatch accumulation was studied on Dothan sand loam (fine‐loamy, siliceous, thermic Plinthic Paleudult) in an experimental putting green planted to three bermndagrasses [Cynodon dactylon(L.) Pers. × C. transvaalensisBurtt‐ Davy] cultivars Tifdwarf, Tifgreen, and a selection called Dothan. Practices evaluated included N source, core aerification, vertical mowing, and sand topdressing. A multiple split plot experimental design allowed the evaluation of each individual practice in combination with all others. Effects of treatments on thatch were determined by measuring thatch depth and the compressibility of the turf surface with a thatch compression meter. Thatch accumulation, after three seasons, increased in the order: Tifgreen, Dothan, Tifdwarf. However, the effects of treatments on thatch accumulation were similar for all cultivars. Four topdressings per year reduced thatch accumulation more than a single topdressing and increased mat depth. Neither monthly aerification nor biweekly vertical mowing provided more thatch control than twice yearly application of the respective cultural practice. Fertilization with activated sewage sludge resulted in 14% more thatch than when NH4NO3was the N source. Within a given topdressing frequency, no differences in thatch accumulation occurred among N sources, levels of aerification, or vertical mowing. The regression of millimeters compressibility on thatch depth was not significant. Turf quality was not correlated with thatch depth. Tifdwarf had the greatest accumulation on thatch and also produced high turf quality ratings. Nitrogen source influenced turf quality more than other treatments. Activated sewage sludge produced superior turf quality, although more thatch was produced than when NH4NO3was applied. Cultural practices had no consistent effect on establishment of ‘Pennfine’ perennial ryegrass (Lolium perenneL.) overseeded on the experimental green. Ammonium nitrate produced better ryegrass quality than activated sewge sludge. Plots fertilized with activated sewage sludge had significantly more annual bluegrass (Poa annuaL.) than those receiving NH4NO3. Core aerification, topdressing, nor vertical mowing frequency affected ryegrass quality or annual bluegrass occurren
Sulfate Uptake Kinetics of Three Annual Range Species1
Authors: Shock Clinton C. , Williams William A.
Published: July 2010

The sulfate uptake rates of roots of three annual forages were found to follow different Michaelis‐Menten kinetics. Depletion of added sulfate from the nutrient medium by intact plants gave more reproduceable results than excised roots. Subclover (Trifolium subterraneumL.) showed the lowest affinity for sulfate but a high maximal rate of sulfate uptake. Soft chess (Bromus mollisL.) showed bimodal behavior either with a very high affinity and a low maximal uptake or low affinity with high maximal uptake, suggesting that two uptake mechanisms operate in this species. Sulfate uptake rates decreased with plant age for all three species. The decrease was greatest with filaree [Erodium botrys(Cav.) Bertol.] and least with soft chess. A root temperature of 4°C reduced sulfate uptake by all species implying that sulfate uptake depends on active metabolism. When returned to 20°C, sulfate uptake rates for subclover and filaree recovered immediately, but soft chess recovered only partially. Reduced O2from aeration with N2gas decreased sulfate uptake rates for subclover and soft chess but not for filaree. Subclover recovered quickly to the uptake rates observed before treatment, but soft chess did not. Selenate and molybdate interfered with sulfate uptake. Molybdate at 20 µMhad rapid deleterious effects on the root systems of all species. Selenate at the 20 µMconcentration showed no effect on soft chess, but sulfate uptake of filaree and subclover was reduced initially and plant death occurred within 24 h. The ecological significance of sulfate uptake kinetics is discussed with respect to botanical composition changes that occur with increased S supplies on deficient rangelands.
Effect of Etridiazol and Nitrapyrin Treated N Fertilizers on Soil Mineral N Status and Wheat Yields1
Authors: Liu Shyilon L. , Varsa E. C. , Kapusta G. , Mburu David N.
Published: July 2010

Etridiazol[5‐ethoxy‐3‐(trichloromethyl)‐1,2,4‐thiadiazole] and nitrapyrin [2‐chloro‐6‐(trichloromethyl)pyridine] are two nitrification inhibitors that offer potential for reducing N losses in soils from denitrification and leaching, thereby improving N utilization by crops. The objective of this study was to evaluate the ability of these two compounds to reduce nitrification of applied N fertilizers in soils and influence wheat (Triticum aestivumL.) yields. Experiments were conducted in 1977, 1979, and 1980 on Weir (fine, montmorillonitic, mesic Typic Ochraqualfs) and Stoy (fine‐silty, mixed, mesic Aquic Hapludalfs) silt loam soils, typical for wheat production in southern Illinois. Anhydrous ammonia, urea, and urea‐ammonium nitrate (UAN) solutions were applied without and with the two inhibitors at 0.56 and 1.12 kg/ha. Nitrogen rates varied incrementally from 0 to 150 kg/ha. Fertilizers with the inhibitors were applied in the fall prior to wheat seeding. Mineral N forms in soils were determined periodically after application. Etridiazol and nitrapyrin were equally effective in reducing nitrification of ammonium N in soils up to 160 days following application when compared to nontreated fertilizers. Above normal precipitation and temperature tended to reduce inhibitor effectiveness. Both inhibitors at the higher rate generally had greater amounts of NH+4‐N present in soils on any date following application than the lower rate. Treating N fertilizers increased wheat yields from zero up to 32% above nontreated comparisons applied in the fall. Greatest responses were always associated with climatic and soil conditions that favored N losses by denitrification. No yield benefits accrued from the use of inhibitors when the applied N was not subject to loss conditions. Nitrification inhibitors added to fallapplied N resulted in wheat yields that were similar to and occasionally greater than those obtained from spring N topdressings.
Multistrain vs. Single Strain Rhizobium japonicum Inoculants for Early Maturing (00 and 000) Soybean Cultivars: N2Fixation Quantified by 15N Isotope Dilution1
Authors: Rennie R. J. , Dubetz S.
Published: July 2010

Early maturing soybean cultivars (groups 00 and 000) adapted to western Canada are now available but since the soils contain no indigenous Rhizobium japonicum, it is important to determine if strains selected for efficient N2fixation with American soybean cultivars are also efficient with Canadian cultivars and if single strain are superior to multistrain inoculants. Accordingly, a 2‐year evaluation was made of the effect of up to eight single strains and two commercial multistrain combinations of R. japonicumgranular inoculants on maturity, seed yield, oil and protein content, and N2fixation (as determined for the first time by 15N isotope dilution) for three promising soybean lines. Rhizobium japonicumstrains 61A148 (USDA 142) and 61A118 (USDA 138) were consistently superior in N2fixation with all soybean cultivars, resulting in seed yields and seed protein higher than those of the other strains. Strain 61A101 was consistently an inefficient N2fixer. These differences in efficiency between strains were not related to documented ability to take up H2evolved by nitrogenase because, although strain 61A148 is considered Hup+, strain 61A118 is Hup–. Several strains resulted in percent plant N derived from the atmosphere exceeding 50% with N2fixed as high as 151 kg N ha−1for strain 61A148 on King Grain line X005. However, over all strains, Maple Amber was superior for supporting N2fixation, averaging 91 kg while X005 had 83 kg and Maple Presto 60 kg N fixed ha−1. Line strain combinations resulting in lower levels of N2fixation assimilated more soil N such that total N yields averaged over lines and strains were generally similar. These strains selected for U. S. soybean cultivars are also acceptable for Canadian soybeans. Interstrain competition occurred with one multistrain inoculant, to the detriment of plant yield. A commercial mix containing four strains (61A101, 61A118, 61A124, 61A148) had low N2fixation similar to that of strain 61A101. This suggested that strain 61A101 was highly competitive and may have formed a majority of the nodules thereby excluding the highly efficient strains 61A118 and 61A148. However, a new commercial mix containing three strains which were clones of 61A101, 61A118, and 61A124 did not exhibit any detrimental interstrain competition. Thus, the new multistrain soybean inoculant can be recommended for Canadian soybean cultivars.
Microclimate of a Rainfall Shelter1
Authors: Dugas W. A. , Upchurch D. R.
Published: July 2010

To induce water stress on crops grown in areas where extended periods without precipitation during the growing season are infrequent, rainfall shelters are increasingly being used. Shelters are moved over plots during or previous to precipitation. The microclimatic effects of a large (18 ✕ 48 m) fiberglass shelter near Temple, TX were investigated. Air temperature, solar radiation, wind speed, and relative humidity measurements were made throughout two growing seasons to determine the effect of the shelter on the canopy microclimate (relative to the microclimate outside the shelter) when the shelter was off and over the plots. When the shelter was over the plots, the effects upon wind speed and radiation, which were affected most, were consistent; radiation was reduced from 30 to 40% and, because of shelter design, wind speed was reduced to nearly zero. Generally, air temperature and humidity effects were dependent upon temperature and radiation levels. Air temperature differentials greater than 6°C developed within an hour after movement of the shelter over the plots, while radiation and wind effects occurred instantaneously. When off the plots, the shelter's microclimatic effects were not detectable. Under certain conditions, however, the shelter may significantly affect the microclimate. Therefore, researchers using shelters need to investigate the microclimate under a shelter for proper interpretation of plant responses to the environment.
Climate, Management, and N Effect on Corn Leaf N, Yield, and Grain N1
Authors: Asghari M. , Hanson R. G.
Published: July 2010

Two field corn (Zea mays L.) N response experiments, with previous cropping of alfalfa (Medicago sativa L.) and wheat (Triticum aestivum L.), were conducted for 4 years (1977 to 1980) on Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf). The study was conducted to relate the climatic factors of air temperature in June, July, and August, expressed as heat units, and precipitation during the same months to corn yield response to fertilizer N. A previous evaluation utilized grain N (a quantitative measurement) as measure of plant N sufficiency to develop a model integrating these climatic factors to predict total Nand fertilizer N requirements. The objective of this study is to integrate the variables of fertilizer N application by leaf N (a relative plant nutrient measurement) concentration with climatic parameters to predict N requirements for maximum yield. Regression analyses related relative yield to monthly precipitation, heat units, and their products of leaf N or applied N and the square of leaf N or applied N. The primary N source affecting leaf concentrations was from fertilizer N when corn followed wheat and from the previous crop residue when corn followed alfalfa. The critical leaf N concentration of 2.09 mol kg−1 was selected when relative yield of 97% was achieved, because additional increases in leaf N had little effect on yield. Precipitation and heat units accounted for 32 and 62% of the ear leaf N concentration when corn followed wheat and alfalfa, respectively. Including linear and quadratic terms of fertilizer N explained 98 and 92% variability, respectively, in the leaf N, and the fertilizer N requirements for yield maximization were calculated to be 152 and 66 kg ha−1 where corn followed wheat and alfalfa, respectively. This corresponded to 137 and 48 kg N ha−1 fertilizer requirements when 1.09 mol kg−1 grain N was used as the criterion for maximum yield. The summation of precipitation and heat units into the monthly periods of June, July, and August were significantly related to leaf N and grain N. Results indicate that leaf N concentration as well as grain N, can be used as a tool to quantify the N sufficiency and N fertilizer requirements for maximum corn yield.
Influence of Soybean Pubescence Type on Radiation Balance1
Authors: Nielsen D. C. , Blad B. L. , Verma S. B. , Rosenberg N. J. , Specht J. E.
Published: July 2010

Increasing the density of pubescence on the leaves and stems of soybeans (Glycine max L.) should influence the radiation balance of the soybean canopy and affect the evapotranspiration and photosynthetic rates. This study was undertaken to evaluate the influence of increased pubescence density on various components of the radiation balance. Near‐isogenic lines of two soybean cultivars (Clark and Harosoy) were grown in four adjacent small plots (18 ✕ 18 m) during the 1980, 1981, and 1982 growing seasons near Mead, Nebr. The soil at this site is classified as a Typic Argiudoll. The isolines of each cultivar varied only in the amount of pubescence (dense vs. normal pubescence). Measurements of albedo, reflected photosynthetically active radiation (PAR), emitted longwave radiation, and net radiation were made over the crop surfaces with instruments mounted on a rotating boom located at the intersection of the four plots. Radiative canopy temperatures were measured with a handheld infrared thermometer (IRT). Results show that dense pubescence increased reflection of shortwave radiation and PAR by 3 to 5% and 8 to 11%, respectively. Emitted longwave radiation and radiative canopy temperature were not significantly affected by increased pubescence, although there was a slight tendency for the dense pubescent canopy to be cooler. Increased pubescence decreased net radiation over the canopy by 0.5 to 1.5%. These results suggest that soybeans with dense pubescence may be slightly better adapted to the high radiation, high temperature, and limited moisture conditions of the eastern Great Plains than are those with normal pubescence.
Timing and Rate of K Application for Wheat‐Soybean Double Cropping on a Sandy Soil1
Authors: Elwali A. M. O. , Gascho G. J.
Published: July 2010

The wheat [Triticum aestivum (L.) em. Thell.] and soybean (Glycine max (L.) Merr.] double cropping sequence is an important cropping system in the Southern Coastal Plain of the USA. A study was conducted for two crop cycles to determine the optimum timing of supplying adequate K on a Bonifay sand (loamy, siliceous, thermic grossarenic, Plinthic Paleudult). Treatment variables consisted of five K application timings at two Mg rates (0 and 40 kg ha−1) in the first crop cycle, and four K application timings at four rates of K (90,135,180, and 225 kg ha−1) in the second crop cycle. Significant leaching of K from the 0 to 15 and 15 to 30 cm depth was measured when all of the K fertilizer was applied at wheat planting. Potassium uptake and grain yield of wheat were significantly greater for treatments in which one‐half of the total K fertilizer was applied at wheat planting and the remainder in February or as one‐fourth at wheat planting, one‐half in February and the remainder at 6 to 8 weeks after soybean planting compared with the application of all of K fertilizer at wheat planting, application of K at planting of both crops or split application of K in four equal increments on both crops. However, soybean yields were not significantly affected by the treatments in either cropping cycle. Application of Mg in the first cycle increased both soil and plant Mg concentrations but had no significant effect on yields. Increasing rates of K linearly increased wheat yield and soil K at soybean planting but had no significant effects on soybean yield or soil K at the end of the season. We concluded that delaying the application of at least one‐half of the K fertilizer until spring is essential for maintaining adequate K in the rhizosphere of wheat plants on deep sands.
Growth of ‘Braxton’ Soybeans as Influenced by Irrigation and Intrarow Spacing1
Authors: Ramseur E. L. , Wallace S. U. , Quisenberry V. L.
Published: July 2010

Achievement of maximum crop yields necessitates the study of factors influencing yields. The influence of irrigation regime and plant population on growth of a Group VII determinate soybean [Glycine max (L.) Merr.] was measured to determine if a particular growth pattern would result in increased yield. In 1980 and 1981, ‘Braxton’ soybeans were grown in 0.91‐m rows on a Cecil sandy loam (clayey, kaolinitic, thermic Typic Hapludults) under full‐season irrigation (FSI), irrigation beginning at bloom (BI), and no irrigation (NI). Intrarow spacings ranged from 43 or 61 to 457 mm. At growth stage R2, FSI, BI, and NI plants had attained 72, 66, and 75%, respectively, of maximum height and 38, 35, and 55%, respectively, of maximum vegetative dry weight. Height, stem diameter, and dry weight were greater in the irrigated treatments than in NI. Fullseason irrigated plants were generally taller than BI and NI plants and had 1.7 times more dry weight at R2. With increasing spacing, height decreased while stem diameter increased. Vegetative weight was maximized at spacings of 76 mm or less. Development of canopy cover and LAI was more rapid with decreasing spacing and with irrigation. At least 90% canopy closure was obtained in all spacings of FSI and BI, whereas only 59% was achieved in NI. Yields were the same for FSI and BI, and, within irrigation treatments, there were no yield differences among spacings of 305 mm or less. We conclude that comparable yields can be obtained within a wide range of growth patterns, and that severe reductions in vegetative growth at R2 may have little influence on yield if water is supplied thereafter.
Row Spacing and Seeding Rate Effects on Yield and Yield Components of Soft Red Winter Wheat1
Authors: Joseph K. D. S. M. , Alley M. M. , Brann D. E. , Gravelle W. D.
Published: July 2010

Information to determine optimum row spacing and seeding rates for soft red winter wheat (Triticum aestivum L. em Thell.) in high‐yielding environments in the mid‐Atlantic Coastal Plain region is not available. Three field experiments were conducted in the Coastal Plain of Virginia (on Typic Hapludult and Aquic Quartzipsamments soils) to evaluate row spacing and seeding rate influences on grain yield of winter wheat grown with intensive management. Seeding rates ranging from 186 to 558 seeds m−2 were studied in row spacings of 10 and 20 cm with additional treatments of 744 and 1116 seeds m−2 in 10‐cm row spacings. Intensive management included adequate supplies of P, K, and micronutrients as preplant fertilizer, insecticide, and fungicide use, and split‐spring N applications. Measurements included wheat grain yield and yield components. Ten‐centimeter row spacings produced 0.6 to 0.8 Mg ha−1 higher grain yields than 20‐cm row spacings at similar seeding rates. Yield levels ranged from 5.0 to 8.1 Mg ha−1. Heads m−2 and kernels head−1 varied with seeding rate to a greater extent than weight kernel−1. Yields did not vary over a wide range of plant populations, but were reduced with low (469 heads m−2) or high (897 heads m−2) harvest populations. Seeding rates of 372 to 744 seeds−2 in 10‐cm rows were sufficient to produce high yields with the ‘Tyler’ cv. grown under intensive management.
Grain Sorghum Response to Tillage Method Used during Fallow and to Limited Irrigation1
Authors: Baumhardt R. L. , Zartman R. E. , Unger P. W.
Published: July 2010

In the Southern High Plains, grain sorghum [Sorghum bicolor(L.) Moench] is grown under various irrigation regimes from full irrigation to dryland. Continued water depletion from the Ogallala Aquifer and increasing expense of pumping water have resulted in a need for developing more water‐efficient irrigated crop production systems for this area. An experiment was conducted to determine the response of grain sorghum to limited irrigation and fallow management. Winter wheat (Triticum aestivumL.) residue was managed during fallow by either no‐tillage or disk‐tillage practices. The sorghum was grown dryland or received one well‐timed growing‐season irrigation. Precipitation stored as soil water during an 11‐month fallow period was significantly higher with no‐tillage than with disk‐tillage where 1.1 kg residue m‐2 was present, but not where only 0.2 kg m‐2 was present. Dryland no‐tillage yields were greater than disk‐tillage due to greater stored water at planting. A significant irrigation × tillage interaction was found for grain yield and water use efficiency only when water stress was severe at the time of irrigation. The combination of no‐tillage during fallow after wheat and a single, well‐timed irrigation for a succeeding sorghum crop was found to be a suitable transition system from an irrigation‐on‐demand to a dryland production system.
Interactive Effects of Pot Geometry, Water Management, Salinity, and Growing Medium on Growth and Yield Components of Snapbean in the Greenhouse1
Authors: Campbell W. F. , Wagenet R. J. , Jones A.
Published: July 2010

Results of greenhouse experiments vary with pot size and shape, i.e., surface area/depth ratio (S/D), even when genetic, environmental, and nutritional factors are held constant. This paper demonstrates the importance of the S/D ratio on snapbeans (Phaseolus vulgarisL.) as influenced by salinity, water management, growing medium, and soil surface mulch. In the first experiment, plant dry weight, pod and seed number, and seed weight of ‘Blue Lake’ snapbean (bush‐type) were significantly reduced as the S/D ratio and electrical conductivity (EC) of the irrigation water increased. Plant dry weight was also affected by changes in watering interval (WI). With the exception of the EC × WI interaction, all of the interactions significantly affected plant dry weights. The S/D × EC interaction significantly affected seed number and seed weight per plant. In the second experiment, plant dry weight and pod and seed number per ‘Earliwax’ snapbean plant were significantly affected by S/D, water quantity (WQ), substrate type (ST), and WI. Substrate type and WI significantly affected seed weight per plant. Interactions involving S/D ratios, WQ, and WI significantly affected yield components. Soil surface mulches alone did not significantly influence individual yield components, but had significant effects in combination with S/D and WQ. Both of these experiments demonstrated the importance of S/D ratio on plant yield and provide further proof that the results of greenhouse experiments are not likely to correspond to those in the field.
Influence of Tillage on Nutrient Uptake and Yield of Corn1
Authors: Hargrove W. L.
Published: July 2010

Though it appears that the surface accumulation of soil nutrients and the shallower distribution of roots is not detrimental to crop growth and yield under no‐tillage management, supportive data with respect to nutrient uptake are scarce. A field plot study was conducted over 3 yr utilizing four tillage treatments: (i) conventional tillage (moldboard plow); (ii) no‐tillage (coulter); (iii) no‐tillage with shallow (10 to 15 cm) in‐row chisel; and (iv) no‐tillage with deep (30 to 45 cm) in‐row chisel. The objective was to determine the influence of tillage on nutrient uptake and yield of corn by: (i) measuring changes in distribution of soil nutrients; (ii) determining the nutrient status of corn plants; (iii) measuring rubidium (Rb) uptake by corn plants when Rb was placed at various row positions and depths in the soil profile; and (iv) measuring grain yields. No‐tillage treatments resulted in a redistribution and concentration of soil nutrients at the soil surface, compared with conventional tillage. However, the nutrient status of plants grown under no‐tillage management was equal or superior to those grown by conventional tillage. Furthermore, the activity of roots and the extraction of water and nutrients, as evidenced by Rb uptake, was greater for no‐tillage compared with conventional tillage. No‐tillage, whether in‐row chisel was included or not, resulted in larger plants and greater grain yields. No evidence was obtained that would support deeper placement of nutrients or in‐row chisel operations to improve subsoil rooting under no‐tillage.
Deep Placement Effects of Nitrogen and Phosphorus Grain Yield, Nutrient Uptake, and Forage Quality of Winter Wheat1
Authors: Westerman R. L. , Edlund M. G.
Published: July 2010

Nitrogen and P applied together in deep‐band applications have been reported to increase crop production over that obtained with conventional applications. Little information is available on the continuous use of this method of application. Therefore, the objective of this study was to compare the effects of N, P, and N plus P knifed in bands with conventional broadcast methods on grain yield, N and P uptake in grain, and concentration in wheat forage when applied several years at the same location. Winter wheat (Triticum aestivumL.) was grown at three locations from 1980 to 1983. Two N sources, anhydrous ammonia (AA) and ammonium nitrate (AN), one P source, ammonium polyphosphate (APP), and one nitrification inhibitor source, nitrapyrin (NI), were used. Rates of N, P and NI were 112, 30, and 0.56 kg ha−1, respectively. Methods of N and P fertilization included broadcast (BC) and knifed (KF) in bands 15 cm deep with 45‐cm spacings. Crops responded to N fertilization at Altus (southwest location), N plus P at Stillwater (northcentral), and P at Haskell (northeast). Effects of methods of application varied with locations and years. The first year, at Stillwater was the only occurrence of N and P knifed in that resulted in higher yield and N and P uptake in grain compared with broadcast methods. However, with continued fertilization in the same plots with subsequent years, the positive effect of fertilizer in deep placed bands diminished, and broadcast applications were more efficient. Broadcast P applications were more efficient in later years of the study at Haskell where the greatest response to P fertilization was obtained. No long‐term benefits due to placement of N and P together or in combination with NI in deep bands were observed at any of the three locations.
Influence of Climatic Factors and Forage Age on the Chemical Components of Ryegrass Related to Grass Tetany1
Authors: Cherney D. J. R. , Robinson D. L.
Published: July 2010

Climatic factors are known to influence several soil‐plant‐animal relationships, including many criteria used to evaluate the grass tetany potential of forages. Specific climatic influences on these criteria are not well understood. Our objectives were to evaluate effects of growth temperature, soil moisture level, length of flooded period, and forage age on the following forage chemical parameters that have been associated with the incidence of grass tetany: N, K, Ca, Mg, AI, and total water‐soluble carbohydrate (TWSC) concentrations plus ratios of N/TWSC and K/(Ca+Mg). Annual ryegrass (Lolium multiflorurnLam.) grown in growth cabinets at two day/night temperatures (21/13 and 5/0 °C), two soil moisture levels (flooded and optimum), and three flooded periods (7, 14, and 21 days) was harvested 35,42, and 49 days after planting. Regrowth tissue was harvested on Day 49 from plants harvested on Days 35 and 42 (14 and 7 days regrowth, respectively). Temperature and soil moisture variables were initiated 21 days after planting in Tensas silty clay (Vertic Ochraqualf) collected from a tetany‐prone pasture. Ryegrass exposed to 5/0 °C for 2 weeks consistently contained less than the critical Mg level of 2.0 g kg−1, while that grown at 21/13 °C always contained > 2.0 g kg−1Mg. Concentrations of Mg, Ca, K, and N were higher in younger tissue than older tissue and higher in regrowth than in first growth tissue. Regrowth tissue produced at low temperatures contained only 2.0 g kg−1Mg, but over 34 and 51 g kg−1N and K, respectively, and had K/(Ca + Mg) ratios exceeding 3.0. Concentrations of TWSC were also very low in regrowth tissue. Although soil moisture effects were small, Mg concentrations were lower under flooded soil conditions. Forage AI concentrations were generally < 50 µg g−1, regardless of environmental conditions imposed or age of forage at harvest, indicating that AI level was not a factor in determining the grass tetany potential of ryegrass under these conditions. The study shows that grass tetany potential of ryegrass is higher after cold, wet periods and that young regrowth tissue can increase that potential
The Relationships of Nitrate Concentrations in Young Corn Stalks to Soil Nitrogen Availability and Grain Yields1
Authors: Iversen K. V. , Fox R. H. , Piekielek W. P.
Published: July 2010

The importance of N in crop production makes accurate estimation of the available N in the soil desirable, especially with increasing costs of N fertilizers and concern for environmental hazards associated with excessive fertilization. Although several soil N availability indices have been developed, none of those tested has had wide success in Pennsylvania. A 2‐yr study was conducted in central Pennsylvania to determine if nitrate (NO−3) analysis of young corn plants (Zea maysL.) was significantly related to soil N availability. The NO−3contents of basal stalks were determined weekly for several weeks after emergence in two N fertilizer response experiments in 1982 and 1983. The soil in sites in 1982 and 1983 were Murrill silt loam, a Typic Hapludult, and Hagerstown silt loam, a Typic Hapludalf, respectively. Stalk NO−3−N increased with increasing N fertilizer rates. The effect of plant age on stalk NO−3concentration varied between the 2 yr, probably due to hail damage or available water differences. Differences in stalk NO−3among N fertilizer treatments increased with time in both years. The optimum time for sampling appeared to be approximately 30 days after emergence (DAE). Correlations of stalk NO−3at this time with relative grain yield and N uptake were significant (r>0.94) both years. Based on regression lines, at approximately 30 DAE, the critical concentration of stalk NO−3−N (for 95% of the plateau yield) was about 11 g NO−3kg−1in 1982, and 16 g NO−3−‐N kg−1in 1983. Combined data from both years had a significant but lower correlation (r=0.754) between stalk NO−3and relative grain yield, with an apparent critical concentration of 15.7 g NO−3−N kg−1. The potential for predicting soil N availability from NO−3tissue testing appears possible if the environmental factors that affect tissue NO−3accumulation can be identified and quantified.
Responses of Sugarbeet to Deficit, High‐Frequency Sprinkler Irrigation. I. Sucrose Accumulation, and Top and Root Dry Matter Production1
Authors: Hang An N. , Miller D. E.
Published: July 2010

Insufficient water frequently limits crop production worldwide. The present study was conducted to determine the effect of deficit daily sprinkler irrigation on sucrose accumulation and root and top dry matter production from sugarbeet (Beta vulgarisL.) grown on loam and sandy soils (Xerollic Camborthids and Xeric Torripsamments, respectively). Applied water ranged from 15 to 100% and 26 to 115% of the estimated evapotranspiration (Et) after near full canopy on the loam and sandy soil, respectively. On the loam soil, root sucrose concentration increased rapidly with time. The rate of increase was lower with adequate soil water than when it was limited. At the final harvest, maximum dry matter production occurred at irrigation rates equivalent to 40 to 50% of estimated Et. On the sandy soil, with limited water, root sucrose concentrations increased to a maximum about 8 weeks after irrigation treatments began and then decreased. With adequate water, root sucrose concentrations increased until harvest. Sucrose concentration was significantly higher with limited than with adequate water until near harvest. Dry matter production increased with increasing water applied up to about 85% estimated Et
Management of Sorghum Under Limited Irrigation1
Authors: Undersander D. J.
Published: July 2010

Grain sorghum [Sorghum blcolor(L.) Moench] is produced with furrow irrigation across much of the semiarid West. Rising energy costs and declining water supplies in some regions have caused many farmers to irrigate with less water than required for maximum yield. Irrigation needs could be reduced if rainfall were used effectively on irrigated land. Research was done at the Texas Agric. Exp. Stn.. Etter, TX from 1979 to 1982 to compare different systems for limited irrigation of sorghum while attempting to maximize the use of rainfall. The study was conducted on graded furrows (0.3% slope) on a fine, mixed, mesic Torrertic Paleustoll (Sherm silty clay loam soil). The irrigation treatments were: 0, 2.5, 3.8, 5.1, and 10.1 (full irrigation) cm applied at each irrigation. The treatment receiving 2.5 cm was irrigated only in every third furrow and the treatment receiving 3.8 cm was irrigated in alternate furrows. All limited irrigation treatments contained furrow dams spaced 3 m apart. Total water applied varied with years due to rainfall. The seeding rate was varied down the row on plots that received 2.5, 3.8, and 5.1 cm per irrigation. Variable seeding rate was compared with uniform seeding on the 3.8 cm water treatment. Every third row was left blank on the 2.5 cm water treatment. Limited irrigation reduced runoff compared to full irrigation. Water advanced further down the field in alternate than in every furrow irrigation. The dams of non‐irrigated furrows were left in better condition to retain water from precipitation than in the irrigated furrows. The irrigation water use efficiency of 3.8 cm applied to alternate furrows was higher than 5.1 cm applied to every furrow with no change in yield. The yield and water use efficiencies from plots with uniform seeding rate were equal to those from variable seeding rate plots
Growth and Development of Irrigated Sunflower in the Texas High Plains1
Authors: Unger Paul W.
Published: July 2010

Sunflower (Helianthus annuus L.) is widely adapted in the USA. In the southern Great Plains, it has been planted from March to August, but time of planting affected its growth, yield, and quality. Objectives of this study, conducted on Pullman clay loam (Torrertic Paleustolls), were to determine the effect of planting dates and associated environmental factors on sunflower growth, development, yield, quality, and water use. A better understanding of these effects could lead to improved management of this crop. The sunflower was planted from late March to late July in 1980 and 1981. For each planting, sunflower growth, development, yield, and quality were determined and related to environmental factors by simple correlation and multiple regression analyses. Sunflower planted from early April to early June yielded more than earlier‐ or later‐planted sunflower. Values for most other sunflower variables either increased or decreased progressively from the first to the last planting. Early planted sunflower developed slower and used more water than later‐planted sunflower. Planting after early June also resulted in low water use efficiencies because of lower yields. Consequently, early and late plantings are not recommended because they resulted in lower water use efficiency than sunflower planted from April to early June. Oil concentration of seed decreased with later plantings, which resulted in lower total oil production. Based on this study, sunflower in the Texas High Plains should be planted from about mid‐April to early June to use water efficiently and to obtain favorable yields of seed having a high oil concentration.
Plant Population and Plant Height Effects on Pima Cotton Lint Yield1
Authors: Kittock D. L. , Selley R. A. , Cain C. J. , Taylor B. B.
Published: July 2010

Plant populations of American pima cotton (Gossypium barbadenseL.) and upland cotton (G. hirsutumL.) giving maximum lint yields vary widely in reports in the literature. This study attempts to explain the wide variations in plant populations giving maximum lint yield for pima cotton by considering the plant population X plant height interactions with lint yield. Field tests were conducted for 5 yr at four locations on Anthropic Torrifluvents, Torrifluventic Haplostolls, and Typic Torrifluvents soils. Fifteen pima cotton tests with varied plant populations, and with 1.02‐m row spacing, had plant population, plant height, and lint yield measured on each plot. The relationships among yield, population, and height were analyzed by multiple linear regression in each test. In three of the 15 individual test analyses all regression components were significant. A combined analysis of the 15 tests showed a significant negative (P=0.001) plant population × plant height interaction for lint yield. Most of the plant population and plant height treatment means in these tests were within the range of 20 000 to 200 000 plants ha −1and 60 to 190 cm high. Plant population giving maximum yield decreased about 11 000 plants ha −1for each 10‐cm increase in plant height. Cultivars and irrigation treatments did not greatly alter the interaction. Year and geographical location effects were more varied. The variation in plant population producing maximum lint yield for different plant heights was great enough to explain the varied plant populations for maximum lint yield reported in the literature.