bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitivity Analysis of Parameters Used in Simulating K Uptake with a Mechanistic Mathematical Model1
Authors: Silberbush M. , Barber S. A. 
Published: July 2010

AbstractIn recent years, mechanistic mathematical models for predicting nutrient uptake by plants growing in soil have been developed and verified for P and K uptake. However, detailed sensitivity analyses from an agronomic viewpoint have not been published. The objective of this paper is to determine the relative significance of each of the 11 parameters in the Cushman (1979) model for predicting K uptake by ‘Williams 79’ soybeans (Glycine mar L.) from Raub (fine‐silty, mixed, mesic Aquic Argiudoli) silt loam using a sensitivity analysis. Each variable was used at 0.5 to 2.0 times the initial level obtained experimentally while the remaining parameters were held constant. Analyses were also made where interdependent parameters were varied simultaneously by using assumed interdependance between specified variables. Predicted K uptake was influenced more by changes in root length and root radius than by similar changes in any other parameter. Changes in the soil supply parameters; initial concentration in soil solution, soil buffer power, and effective diffusion coefficient influenced K uptake more than changes in the plant kinetic parameters for the soil‐plant system used.
Root and Shoot Development in Winter Wheat1
Authors: Klepper Betty , Belford R. K. , Rickman R. W. 
Published: July 2010

abstractBetter characterizations of cereal root systems are needed for water extraction models, for relating root and shoot development, and for describing the root systems of individual tillers. This paper presents a naming system for root axes of wheat (Triticum aestivum L. em. Thell). Each axis is described by the number of the node with which it is associated and by the direction of its growth with respect to the leaf borne at the node. Plants were grown in the field on a Walla Walla silt loam (coarse‐silty, mixed, mesic family of Typic Haploxerolls). Examination of the upper 10 cm of roots indicated that root axes were produced at predictable times with respect to shoot development. The number of roots on any culm (Y) could be calculated from the number of leaves on the culm (X) (Y = 1.95 X –3.06, r2= 0.9). The presence of lateral roots could be predicted if data were plotted to relate root axis development to a phyllochron or degreeday scale.
Yield, Water‐Use Efficiency, and Oil Concentration and Quality of Dryland Sunflower Grown in the Southern High Plains1
Authors: Jones Ordie R. 
Published: July 2010

AbstractFor oilseed sunflower (Helianthus annuusL.) to develop as a competitive crop on the drylands of the Southern High Plains, information is needed concerning the effects of various agronomic practices on sunflower production in this area. The objectives of the research were to determine the effects of seeding date, plant population, and soil water content at time of seeding on dryland sunflower seed yield, water‐use efficiency (WUE), and oil concentration and quality. The study was conducted from 1975 through 1979 on Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). Seeding date had the greatest effect on seed yield and WUE and reflected the effects of seasonal precipitation patterns. Yield response to increased soil water content at seeding was 0.70 kg seed/m3water. Plant populations in the range of 2.5 to 4.5 plants/m2resulted in similar seed yields and WUE , but high populations (>3.5 plants/m2) tended to increase oil concentration. Seeding date significantly influenced oil concentration and quality with April seedings having a 50 to 80 g/kg greater oil concentration than July seedings. Oleic acid concentration in sunflower oil decreased, and conversely, linoleic acid concentration increased as seeding dates became later. Thus, by manipulating seeding dates, oil of a quality suited to a particular need (margarine, cooking or salad oil) may be produced. Yield potential was enhanced when soil water content at seeding was increased, indicating that sunflower is adapted for use on water conservation systems or after fallow where additional soil water may be available.
Competition and Allelopathy Between Soybeans and Weeds1
Authors: Rose Steven J. , Burnside Orvin C. , Specht James E. , Swisher Beth A. 
Published: July 2010

AbstractThis research was initiated to determine how soybean [Glycine max (L.) Merr.] cultivars differ in competitive ability and also whether allelopathy functions to inhibit surrounding weed growth. Initially 280 soybean cultivars were screened in the field for competitive ability based on emergence, seedling vigor, quickness of canopy closure, and ability to inhibit growth of velvetleaf (Abutilon theophrasti Medic.) and foxtail millet [Setaria italica (L.) Beauv.]. Experiments were conducted at Lincoln, Nebr. on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudolls) during 1981 and 1982. Soybean cultivars of later maturity tended to compete more effectively with weeds. Competitive cultivars emerged quickly, rapidly formed a canopy, and were able to slow the growth of competing weed species. Twenty soybean cultivars of varying competitive ability were selected and grown in the greenhouse during 1981 and 1982 to determine the importance of allelopathy in competing with weeds. Exudates from roots of soybean cultivars grown in sand reduced the dry weight of 4‐week‐old velvetleaf plants an average of 15%, but foxtail millet was not inhibited. Incorporation of 1% ground soybean dry matter into Sharpsburg silty clay loam inhibited germination and dry weight of greenhouse grown velvetleaf an average of 46% each. Foxtail millet germination and dry weights were reduced an average of 82 and 65%, respectively. Undiluted soybean plant extracts of all cultivars tested slowed the germination and dry weight accumulation of 6‐day‐old velvetleaf and foxtail millet, but dilution of the extracts caused quite variable responses. Osmotic potential of the extract solution appeared to be the main cause of inhibition, however, extracts of some cultivars, diluted to decrease the osmotic potential, still inhibited growth. Allelopathy appears to be one mechanism for competition among soybeans and weeds. Soybean cultivars possessing the ability to chemically inhibit competing weed growth would be a great benefit to the soybean producer.
Drought Response of Grain Legumes Under Irrigation Gradient: I. Yield and Yield Components1
Authors: Pandey R. K. , Herrera W. A. T. , Pendleton J. W. 
Published: July 2010

AbstractFood legumes are widely grown as a source of protein in semiarid and tropical regions, but production is often limited by the large variation in the amount and distribution of rainfall. Mungbean (Vigna radiata L.), cowpea (Vigna unguiculata L.), soybean (Glycine max L.), and peanut (Arachis hypogeae L.), often planted after rice (Oryza sativa L.), were compared for response to a season‐long moisture stress on medium‐deep Tropudalf soil, using a line‐source sprinkler irrigation system during the January to April 1982 dry season. Drought stress reduced seed yield of all four food legumes, but the reduction due to water stress was greater in mungbean followed by soybean, cowpea, and peanut. Mungbean produced significantly lower yields at all moisture levels than the other legumes. Total water use by peanut was highest, followed by cowpea, soybean, and mungbean. Among yield components, the numbr of pods per square meter was most affected by water stress in all four species, followed by number of seeds per pod, while seed weight was least affected. Harvest index decreased Linearly with increasing levels of drought for all four species.
Drought Response of Grain Legumes Under Irrigation Gradient: III. Plant Growth1
Authors: Pandey R. K. , Herrera W. A. T. , Villegas A. N. , Pendleton J. W. 
Published: July 2010

AbstractPlant growth in semiarid and tropical regions is often limited by variations in the amount and duration of rainfall. Four food legumes, mungbean (Vigna radiata L.), cowpea (Vigna unguiculata L.), soybean (Glycine max L.), and peanut (Arachis hypogeae L.) were subjected to different moisture gradients in the field on a medium‐deep Tropudalf soil. Water stress effects on the shoot and root growth were analyzed to determine relationships with seed yield and plant growth and to evaluate possible drought avoidance mechanisms. Water stress was created with a line‐source sprinkler irrigation system. Plant growth analyses were computed from samples taken at frequent intervals during the vegetative and reproductive phases. Increasing moisture stress resulted in progressively less leaf area, leaf area duration (LAD), crop growth rate (CGR), and shoot dry matter. Conversely, specific leaf weight increased with increasing levels of water stress. The four seed legumes differed in their ability to maintain leaf area expansion rate, leaf area index, LAD, CGR, and shoot dry matter at high levels of water stress. Cowpea and peanut had higher root densities at 0.4 to 0.8 m soil depths than soybean or mungbean and this appeared to be a major adaptive mechanism for their drought tolerance.
Leaf Water and Turgor Potential Threshold Values for Leaf Growth of Wheat1
Authors: Eastham Judy , Oosterhuis Derrick M. , Walker Sue 
Published: July 2010

AbstractEnvironmental factors affecting leaf growth must be understood for accurate predictions of yield by crop modeling. Water is one of the most important of these factors. The effect of water deficits on the relationships between leaf elongation and leaf water and turgor potentials was investigated on wheat (Triticum aestivumL.) grown under field conditions on a Rhodic Paleustalf on the Highfeld Plateau of the Republic of South Africa. Leaf growth rates of water stressed and nonstressed wheat were measured, and corresponding values of leaf water, osmotic and turgor potentials obtained using thermocouple psychrometers. Water stress resulted in a reduced growth rate and a lower total cumulative growth. The growth curve was made up of two phases, an initial phase of both lamina and leaf sheath elongation, and a second phase of leaf sheath elongation alone. The different relationships between growth rate and midday leaf turgor potential in the two phases indicated leaf sheath elongation to be more sensitive to stress than lamina elongation. The water‐stressed treatment had a lower water potential threshold value for elongation of ‒2571 kPa compared with ‒1671 kPa for well‐watered plants. Turgor potential threshold values for elongation in the stressed plants were also lower by 197 kPa for the phase of leaf lamina and sheath elongation, and by 488 kPa for the phase of sheath elongation alone. Stress acclimation apparently occurred by osmotic adjustment to maintain turgor potentials necessary for elongation.
Yield and Composition of Tall Fescue Stockpiled for Different Periods1
Authors: Fribourg Henry A. , Bell Kenneth W. 
Published: July 2010

AbstractStockpiling of late summer and early autumn growth can provide forage for grazing during late autumn and early winter when small amounts of forage are produced in the U.S. humid mesothermal regions. Three experiments were conducted on Typic Paleudult, Typic Paleudalf, and Typic Hapludult soils to quantify the amount and composition of tall fescue [Festuca arundinacea (L.) Schreb.] forage stockpiled in summer and/or autumn following frequent clipping prior to stockpiling. These forage yields were compared to the regrowth after stockpiled forage removal and to continuously clipped fescue. Treatments consisted of combinations of date of stockpiling initiation and duration of stockpiling. Stockpiling started in July or August resulted in accumulations of 1.0 to 1.4 Mg ha−1 dry matter (DM) the 1st month, and an additional 1.1 to 1.5 Mg ha−1 the 2nd month. When July stockpiling was extended into September, a further 1.4 Mg ha−1 DM was accumulated. Stockpiling summer growth for grazing in October, November, and December resulted in a small loss of accumulated DM, and large losses occurred when harvest was delayed until January. Crude protein (CP) concentrations for stockpiled forage generally decreased from 80 to 150 g kg−1 of DM at the start of stockpiling to 20 to 90 in winter. Concentrations of aciddetergent fiber (300 to 340 g kg−1 of DM) and neutral‐detergent fiber (620 to 710 g kg−1) did not vary with duration of stockpiling. Concentrations of K were 0.6 to 0.9 mol kg−1 at the start of stockpiling and decreased linearly to 0.15 to 0.30 in winter; P decreased from 0.09 to 0.12 mol kg−1 in summer and early fall to 0.035 to 0.06 in October and later. Stockpiling autumn growth resulted in accumulation of only 1.3 Mg ha−1 DM of relatively high quality forage through December. These data indicate that stockpiling fescue is a viable option in areas receiving 1000 to 1200 mm annual precipitation. Start of forage accumulation may begin as early as the beginning of summer, or may be delayed to late summer or early autumn. Losses of DM and nutrients may be substantial in January or later.
A Generalized Relationship between Photosynthetically Active Radiation and Solar Radiation1
Authors: Meek D. W. , Hatfield J. L. , Howell T. A. , Idso S. B. , Reginato R. J. 
Published: July 2010

AbstractPhotosynthetically active radiation (PAR) is a necessary input in several crop growth models. Previous research from several locations with different instruments has suggested that PAR could be estimated as a constant fraction of shortwave radiation. This study was conducted to determine if a simple relationship was valid for a large geographic area in the western half of the USA. In the semiarid climate near Fresno, CA, the daily photosynthetic photon flux density (PPFD) in units of μmol m−2 was 2.04 ± 0.06 times the solar irradiance (SI). The daily irradiance within the PAR waveband (photosynthetic irradiance (PI), 0.4 to 0.7 μm) was estimated to be 45% of the daily solar irradiance. The diurnal pattern of these relationships was consistent with measurements at Phoenix, AZ and exhibited only a slight diurnal variation. Independent measurements of the solar irradiance between 0.285 and 0.63 μm with “filtered” pyranometers at the Fresno site indicated that irradiance between 0.285 and 0.63 μm was 41% of solar irradiance, a result which was about 7% lower than the estimate from the PAR/SI value converted with a published sun and sky PAR/PI factor. This difference was largely attributed to the differences in measured wavebands. Measurements of solar irradiance less than the waveband of 0.63 μm and total solar irradiance obtained with the same equipment at Brawley, CA; Weslaco, TX; Temple, TX; Manhattan, KS; Lincoln, NE; St. Paul, MN; Fargo, ND; Sidney, MT; Beartooth Pass, WY; Kimberly, ID; Davis, CA were similar to those measured at Fresno, CA. The results indicate that PAR can be estimated from solar irradiance measurements to within 10% (which is probably acceptable for most plant growth models) throughout most of the Western USA.
Wheat Canopy Resistance Determined by Energy Balance Techniques1
Authors: Hatfield J. L. 
Published: July 2010

AbstractCanopy resistances are important to evaluate plant environmental responses and difficult to measure in situ. This study was designed to evaluate a residual energy balance method for obtaining canopy resistances. A field study was conducted under natural rainfall conditions at Davis, CA during 1980 to 1981 on the Yolo silt loam soil (fine‐silty, mixed, nonacid, thermic Typic Xerorthent) with Anza wheat (Triticum aestivum L.) seeded at 120 kg ha−1 with 80 kg ha−1 N supplied prior to planting. One‐half of the plots received unobstructed solar radiation, the other half had solar radiation reduced by a 55% shadecloth. From shortly after emergence to maturity, net radiation, air temperature, canopy temperature, incoming solar radiation, vapor pressure deficit, and windspeed were continually recorded. Canopy resistances were calculated from a residual of the energy balance. Canopy resistances obtained under optimal available soil water for both radiation treatments exhibited exponential decline with increasing solar radiation. Midday values of canopy resistance in the unshaded area were typically 20 to 25 s m−1 and 40 to 50 s m−1 in the shaded plot. Canopy resistance was 20 s m−1 under conditions which would be considered near potential evapotranspiration and, increased linearly with decreasing available soil water with a change in canopy resistance of 0.4 and 2.1 s m−1/% available soil water for the unshaded and shaded, respectively. These were normalized by computing the ratio of canopy resistance under non‐optimal soil water contents to the canopy resistance influenced only by solar radiation. This allowed both solar radiation treatments to fit the same relationship and revealed that canopy resistance was not affected until 20% of the available soil water was removed. The residual energy balance method provides a valuable tool to quantify canopy resistance and will be useful to compare genotypes or management practices.
Deficit Sprinkler Irrigation of Sunflower and Safflower1
Authors: Hang A. N. , Evans D. W. 
Published: July 2010

AbstractIncreasing competition for water supplies and rising costs of applying water make efficient irrigation increasingly important. Yield and water use of sunflower (Helianthus annuusL.) and safflower (Carthanus tinctoriusL.) were evaluated on silt loam soil. Deficit irrigation treatments using the line source method were initiated near the time of canopy closure and continued until maturity. Moisture stress on sunflower and safflower caused shortened plant height, early blooming, early maturity, and decreased seed yield. In 1980 sunflower yields ranged from 2.41 to 4.50 Mg ha−1for 2.5 to 35.0 cm irrigation. In 1981 sunflower yields ranged from 1.56 to 3.37 Mg ha−1for 2.5 to 45.0 cm irrigation. Safflower yields in 1981 ranged from 1.84 to 5.15 Mg ha−1for the same irrigation rates. In 1981, sunflower and safflower received the same total amount of water to produce maximum seed yield. Increased irrigation water results in increased yield for both sunflower and safflower; however, yield per unit applied water decreases with increased irrigation rates so that at some point, the expected increase in yield would not cover the cost of additional water application. Increased irrigation increased oil concentration of sunflower except for cv. 894 in 1980. Oil concentration of safflower did not respond to increased irrigation rates. It was concluded that limiting irrigation on sunflower and safflower to ≤ 30 cm permits utilization of residual soil water on silt loam soil with consequent savings in irrigation water supplies and costs of application. Soil moisture is then recharged by winter rainfall.
Timing of Foliar Manganese Application for Correction of Manganese Deficiency in Soybean1
Authors: Gettier S. W. , Martens D. C. , Brumback T. B. 
Published: July 2010

AbstractA consensus has not been reached on how often and at what growth stage to apply foliar Mn for alleviation of Mn deficiency in soybean [Glycine max(L.) Merr.]. Three field experiments were conducted to determine soybean response to a 1.12 kg Mn ha−1foliar application at the V6 (early), the R1 (late) and at both the V6 and R1 growth stages. Determinate ‘Essex’ soybeans were grown at two locations on Dragston fsl (Aeric Ochraquults) soils and ‘York’ on a Myatt fsl (Typic Ochraquults). The Ap horizon of the soils had pH levels from 6.3 to 6.8 and had low Mehlich 1‐extractable Mn levels from 0.8 to 1.6 mg kg−1. Foliar application of MnSO4increased soybean seed yields up to 2518 kg ha−1over the control. Yield increases were due to increases in seed weight and seed numbers. The average control Mn concentrations in the leaflets, trifoliolate leaves and seeds were 11.4, 9.3, and 8.5 mg kg−1, respectively. More Mn was translocated to the seed from the late than from the early foliar Mn treatment. Seed yields were higher from plants that received a single early spray than a single late spray. Soybean plants that received 1.12 kg Mn ha−1early and again late had higher yields than plants that received a single early spray. Full correction of soybean Mn deficiency by foliar Mn technique required multiple foliar Mn applications.
Defoliation Effects on Two Corn Inbreds and their Single‐Cross Hybrid1
Authors: Vasilas B. L. , Seif R. D. 
Published: July 2010

AbstractHail damage to corn (Zea maysL.) is assessed with the use of loss charts derived primarily from research conducted with hybrids. Little data are available on the relative responses of inbreds vs. hybrids to defoliation. Therefore, field experiments were conducted at the University of Illinois on a Drummer silty clay loam (Typic Haplaquoll) in 1982 and a Flanagan silt loam (Aquic Argiudoll) in 1983 to compare the response to defoliation of two corn inbred lines, FRMol7rhmand FR27rhm, and their single‐cross hybrid. Defoliation treatments of 0,50, and 100% were conducted by hand at the 7‐leaf, 14‐leaf, anthesis, late‐milk, and soft‐dough stages in 1982 and the 7‐leaf, 14‐leaf, anthesis, milk, and dent stages in 1983. Data were taken on grain yield, kernel size, kernel number, and percentage barrens, doubles, and nubbins. The response of the inbreds was quite different than that of the hybrid and showed greater yearly variation because of differences in the growing seasons. Complete defoliation at anthesis reduced grain yield 100% in all cases. The greatest genetic variability was observed with 100% defoliation at the 14‐leaf stage, which reduced FRMol7rhmand FR27rhm✕ FRMo17rhmgrain yields by 90 and 40%, respectively, and increased FR27rhmgrain yields by 2%. In many cases, defoliation increased grain yields by decreasing transpiration or delaying flowering until irrigation water was applied. Yield reductions were due to decreases in kernel size and kernel number. Kernel size was affected most by defoliation at the milk and late‐milk stages. Kernel number was affected most by defoliation at anthesis and the 14‐leaf stage.