bluuebunny/crossref_metadata_2025_split huggingface dataset:
Computational Approach to Assess Actual Transpiration from Aerodynamic and Canopy Resistance
Authors: Ben‐Asher J. , Meek D. W. , Hutmacher R. B. , Phene C. J. 
Published: July 2010

AbstractA simple method for estimating actual transpiration may help to control precise irrigation. The Penman‐Monteith equation can be a useful method, provided data on canopy resistance (rc) and aerodynamic resistance (rav are available. These parameters are complex and hard to obtain. The objective of this study was to estimate rc and rav with infrared thermometers (IRT). Tomato (Lycopersicon esculentum Mill. cv. UC‐82B) grown under various irrigation regimes on a Panoche clay loam soil (fine‐loamy, mixed, thermic Typic Torriorthents) were used to obtain differential values of canopy and air temperatures. With standard climatological data, they were used for the determination of rc and rav. Calculated values of rc and rav were used to estimate actual transpiration rates. A basic assumption is that both rc and rav are crop‐specific coefficients of proportionalities rather than physically measurable parameters. While rc varies according to water availability, rav is not directly affected by soil water status, but is a factor of crop and climatic conditions. Thus, rav determined under conditions approximating potential transpiration (Tp) was also used to evaluate rc under water deficit conditions. Calculated values of rc and transpiration agreed with values measured with a steady state diffusion porometer. A computational link exists between measurements of canopy, air temperature, rc, and rav. Infrared thermometers can be effectively used in irrigation management.
Regional Environment and Cultivar Effects on the Quality of Wheat Straw
Authors: Rao S. C. 
Published: July 2010

AbstractCereal grain residues represent a major portion of crop residues produced in the USA, and could be an important source of feed for ruminants if the nutritive value could be improved. A study was conducted to determine the effects of cultivar and regional environment on the fiber concentration, crude protein (CP), and in vitro drymatter digestibility (IVDMD) of wheat (Triticum aestivum L.) straw. Samples of five hard red winter wheat cultivars (Centurk 78, Newton, Vona, Scout 66, and TAMW‐101), grown at four cultivar test centers in Oklahoma, Kansas, Colorado, and Texas, were collected after harvest during 1983–1984, 1984–1985, and 1985–1986 growing seasons. Samples were ground and analyzed for neutral detergent fiber (NDF), acid detergent fiber (ADF), permanganate lignin (LIG), CP, and IVDMD. No significant differences were observed in fiber content among cultivars within location and year. Cultivars did differ in CP and IVDMD with a significant year ✕ cultivar interaction. A combined analysis showed a significant location ✕ year interaction for all the components tested. Average values for NDF, ADF, and LIG content of all cultivars among locations throughout the study period ranged from 703 to 849,495 to 606, and 73 to 115 g kg−1, respectively, whereas CP and IVDMD values ranged from 18 to 53 and 295 to 449 g kg−1 , respectively. Crude protein increased linearly with mean spring temperature, as did ADF concentrations with cumulative precipitation. Digestibility of wheat straw, however, was not affected by environmental conditions. Environmental factors such as spring temperature and precipitation exerted greater influence on CP and fiber contents, whereas cultivars had little effect on the CP and IVDMD of wheat straw.
Grazing Winter Wheat: II. Height Effects on Response to Production System
Authors: Winter S. R. , Thompson E. K. , Musick J. T. 
Published: July 2010

AbstractCurrent wheat (Triticum aestivum L.) cultivars are shorter and have more lodging resistance than previous cultivars. Thus, the reduction in height and lodging caused by grazing may be less desirable now than previously. The objective of this research was to compare the growth and yield response to grazing of hard red winter wheat cultivars that vary in height and other traits. Siouxland, a tall cultivar, Vona, a semidwarf, and Q588, a short hybrid, were grown 2 yr in irrigated grain and grazed production systems. In 1986, Siouxland yielded the same in grain and grazed systems and was insensitive to grazing termination date except that severe grazing after 15 March reduced yield 20%. In contrast, Vona and Q588 yielded less in all grazed systems than in the grain system and were more sensitive to grazing termination date than Siouxland because they had lower leaf area and headed earlier. Grazing until 29 March reduced yield of Vona and Q588 two to five times more than Siouxland. In 1987, grazing increased yield of Siouxland and Vona by 41 and 23%, respectively, while reducing yield of Q588 by 8% in a lodging‐prone environment (330 mm spring irrigation) because Siouxland and Vona lodged without grazing and Q588 did not. With 130 mm spring irrigation, lodging was less and all cultivars responded similiarly to grazing. In conclusion, grazing is more likely to reduce the yield of a lodging‐resistant short cultivar with high yield potential than a tall cultivar that is susceptible to lodging.
Water Potential in Sugarcane Measured from Leaf Segments in a Pressure Chamber
Authors: Saliendra Nicanor Z. , Meinzer Frederick C. , Grantz David A. 
Published: July 2010

AbstractThe validity of using sugarcane leaf segments to measure leaf water potential with the pressure chamber technique was assessed. Three pressure chamber protocols: (i) use of leaf tips, (ii) leaf segments sealed inside balloons, and (iii) exposed leaf segments, were compared. Measurements obtained using leaf segments were 0.05 to 0.06 MPa higher than those obtained from leaf tips. These small differences in water potential between leaf tips and nonapical segments could be attributed to transpiration‐induced, water potential gradients existing prior to excision. Sealing the excised segment within a rubber balloon inside the pressure chamber altered the apparent water potential by 0.01 MPa or less, relative to exposed leaf segments. The use of leaf segments was more convenient and less destructive of plant material than the use of leaf tips or entire leaves. This protocol proved to be an accurate and reliable way of measuring water potential in sugarcane using the pressure chamber technique.
A Thermal Stress Index for Cotton
Authors: Burke J. J. , Hatfield J. L. , Wanjura D. F. 
Published: July 2010

AbstractThermal stress is difficult to separate from water stress; however, linking enzyme kinetics to plant temperature provides a new description of plant stress. Previous reports have shown that cotton was within its thermal kinetic window (the temperature range over which the value of the apparent Michaelis constant (Km) of enzymes remains within 200% of the minimum observed value) for approximately 30% of the growing season, and that the time the plant temperatures were within the thermal kinetic window (TKW) was related to biomass production. The present study investigated the usefulness of the 27.5 °C midpoint temperature of the TKW of cotton (Gossypium hirsutum L.) as a baseline temperature for a thermal stress index (TSI). Using this biochemical baseline and measurements of foliage temperature, we compared the TSI response with cotton field performance. The study was conducted in the field on an Olton silty clay loam soil (fine mixed, thermic, Aridic PaleustoIIs) during 1984 and 1987. Measurements of foliage temperature were made with a hand‐held 4° field of view (FOV) infrared thermometer and plant biomass measured by destructive sampling. The biochemically based TSI and the physically based crop water stress index (CWSI) were highly correlated (r2 = 0.92) for cotton across a range of environmental conditions. The results indicate that the TSI may be useful in quantifying thermal stress via a procedure related to plant biochemistry.
Branch Dry Weight in Relation to Yield Increases in Narrow‐Row Soybean
Authors: Board J. E. , Harville B. G. , Saxton A. M. 
Published: July 2010

AbstractPrevious studies indicated total dry matter at R5 (TDM,R5) played a more important role in narrow‐row yield increases at late compared to optimal planting dates in soybean [Glycine max (L.) Merr.]. The objective of this study was to test the hypothesis that greater TDM(R5) in narrow vs. wide rows at late plantings stimulates yield by increasing vegetative branch dry matter (BDM,R8), branch yield components, and branch reproductive dry matter (BRDM). Field studies were conducted during 1987 and 1988 at optimal (May) and late (July) planting dates, with two commercial soybean cultivars (Forrest, Maturity Group V and Centennial, Maturity Group VI), and 100‐cm (wide) rows/normal plant population, 50‐cm (narrow) rows/normal plant population, and 50‐cm rows/high plant population. The test was conducted at Baton Rouge, LA on a Mhoon silty clay (fine‐silty, mixed, nonacid, thermic, Typic, Fluvaquents) soil. Narrow compared to wide row spacing resulted in greater BDM(R8) at both planting dates. However, increased BDM(R8) was correlated with whole plot yield (r2 = 0.92***, significant at P = 0.001) only at the late planting. Narrow‐row‐increased BDM(R8) was responsible for greater yield at this planting date because it was associated with increasing branch yield components which are reduced by late planting: branch number, total branch length, branch node number, and branch pod and seed production. In conclusion, data supported the hypothesis that the close association between narrow‐row‐increased TDM(R5) and yield at late plantings is related to increased branch dry matter and branch yield component production.
Tillage and Cover Crop Management for Soil Water Conservation
Authors: Munawar A. , Blevins R. L. , Frye W. W. , Saul M. R. 
Published: July 2010

AbstractThe effectiveness of a conservation tillage system depends on the amount and distribution of plant residues left on the soil surface. We determined effects of tillage systems, N fertilizer rates, and cover crop management on soil temperature, soil moisture, and corn (Zea mays L.) yields. Tillage treatments were chisel‐plow tillage, conventional tillage (moldboard plowing and disking), disk tillage, and notillage. Nitrogen fertilizer at rates of 0, 75, 150, or 225 kg N ha−1 were broadcast on the soil surface. Rye (Secale cereale L.) on one‐half of each split plot was killed 3 wk before corn planting time, while the other half was allowed to grow until the corn was planted. Corn yields in 1986 were 4.41, 4.03, 3.64, and 2.25 Mg ha−1 for notillage, chisel‐plow tillage, disk tillage, and conventional tillage, respectively. The yields were significantly greater with early killed rye (3.85 and 5.05 Mg ha−1 in 1986 and 1987, respectively) than with late‐killed rye (3.32 and 4.58 Mg ha−1 in 1986 and 1987, respectively). Soil temperature tended to be slightly higher under the latekilled rye mulch in 1986 with no significant difference in 1985. Soil moisture content was significantly higher for early killed rye treatment in the early part of the season in 1986 because there was less soil moisture depletion due to the growing rye.
Grain, Dry Matter Yield Relationships for Winter Wheat and Grain Sorghum—Southern High Plains
Authors: Howell Terry A. 
Published: July 2010

AbstractGrain yield of cereal crops is closely associated to the aerial (above ground) dry matter yield, but predictions of grain yield based on model estimates of dry matter yield are often inaccurate due to variations in the assumed harvest index. This study analyzed the relationship between grain yield and aerial dry matter yield from published studies for winter wheat [Triticum aestivum (L.)] and grain sorghum [Sorghum bicolor (L.) Moench) conducted at Bushland, TX in the Southern High Plains. Harvest index (HI) was defined and determined as the slope of the linear relationship between Yd, plant grain yield in Mg ha−1 on a dry basis, and DM, aerial (field) dry matter yield in Mg ha−1, as contrasted to the traditional definition of HI as the ratio YdDM. Simple linear relationships had coefficients of determination of 0.95 for the seven grain sorghum experiments and 0.75 for the five winter wheat experiments at Bushland and standard errors of the estimates of 0.47 Mg ha−1 and 0.63 Mg ha−1, respectively. The HI of winter wheat and grain sorghum at Bushland was 0.35 and 0.47, respectively, and largely unaffected by fertility, water use, row spacing, and many other cultural practices like tillage and profile modification, and growing season environment. The linear regressions indicated a significant (0.05 probability level) intercept value of −0.53 Mg ha−1 for grain sorghum while the intercept value 0.16 Mg ha−1 for winter wheat was not significant (0.05 probability level).
Soil Water Assessment Model for Several Crops in the High Plains
Authors: Robinson J. M. , Hubbard K. G. 
Published: July 2010

AbstractSoil properties, soil water content and precipitation vary widely within the High Plains of the USA. Reliable estimates of crop water status have been hampered by a general sparsity of soil water monitoring. This study examined the feasibility of determining soil water status using a soil water balance model. Soil water content was measured under corn (Zea mays L.), wheat (Triticum aestivum L.), sorghum (Sorghum vulgare L.) and soybean (Glycine max L.) at different sites in the High Plains during 1986 and 1987. Surface weather data collected from the High Plains Automated Weather Data Network (AWDN) served as input to a model that estimates evapotranspiration (ET) and soil water content on a daily time step. Atmospheric demand was represented by potential evapotranspiration (ETp) calculated from the Penman method. Model estimates of total water in the root zone were compared to measured values using statistical measures including the D index of agreement. Comparison at one site between measured and estimated soil water by individual soil layers beneath a corn indicated that water content was slightly underestimated in the upper layers and overestimated in the lower layers. The performance of the model in estimating total soil water over a range of soil types, crops and weather was satisfactory, with the majority of D index values exceeding 0.75. Based on the results of this study, we conclude that it is now possible to accurately estimate soil water conditions in a timely fashion under reasonably flat terrain, provided near‐real time weather data are available.
Reseeding, Biomass, and Nitrogen Content of Selected Winter Legumes in Grain Sorghum Culture
Authors: Boquet D. J. , Dabney S. M. 
Published: July 2010

AbstractWinter legumes as green manure crops in grain sorghum, Sorghum bicolor L. Moench, production on clay soils in the southern USA would be facilitated by increased knowledge of growth responses and reseeding capability of legume cultivars. This study evaluated ‘Tibbee’ crimson, Trifolium incarnatum L.; ‘Bigbee’ berseem, T. alexandrinum L.: ‘Yuchi’ arrowleaf, T. vesiculosum Savi. and ‘Woogenellup’ subterranean, T. subterraneum L. clovers and ‘Woodford’ big flower vetch, Vicia grandiflora Scop., for reseeding, biomass and N content at seven growth termination dates (GTD) 20 and 31 March, 10 and 21 April, and 1, 13, and 22 May 1986. The field experiment was initially planted on 15 Oct. 1985 on a Mhoon silty clay (fine‐silty, mixed, nonacid, thermic, Typic Fluvaquents). No legume was able to reseed the first year when the GTD was on or before 10 April. Crimson and subterranean clover and big flower vetch successfully reseeded at a GTD of 21 April. Berseem clover did not reseed unless the GTD was as late as 13 May, and arrowleaf clover did not reseed at any GTD. The legumes that reseeded the first year also reseeded a second year. Maximum biomass:N (kg ha−1) accumulation was 5500:150 for crimson; 6550:190 for berseem; 6350:152 for subterranean; 6300:203 for arrowleaf clovers; and 2700:80 for big flower vetch. Maximum biomass and N accumulation occurred by the date of reseeding for all five legumes; thus, growth of these legumes need not extend beyond this date to realize all of the green manure benefits. Nitrogen content of all legumes, except big flower vetch, was theoretically sufficient to meet the requirements of a grain sorghum crop without additional N fertilizer.
Quantitative Determination of Total Sulfur in Plant Tissues using Acid Digestion and Ion‐chromatography
Authors: Hafez Ahmed A. , Goyal Sham S. , Rains D. W. 
Published: July 2010

AbstractTotal sulfur determination in plant material can be done either by expensive and sophisticated equipment such as an inductively coupled plasma atomic emission spectrophotometer (ICP‐AES), or tedious and time consuming procedures like the Johnson and Nishita or oxygen combustion method, or by S‐auto‐analyzers. Since ion‐chromatography has demonstrated versatility in inorganic ion analysis, it was adopted in this paper to measure SO4 in wet acid digests of plant materials. Plant tissues (200 mg) were digested with 2 mL HNO3 + 1 mL 70% HClO4 and subsequently evaporated to dryness in order to minimize the HClO4 concentration for efficient ion‐chromatography. Magnesium oxide was dissolved in HNO3 at a rate of 1.25 g L−1 to provide cations to prevent the losses of S gases. Dionex OmniPac PAX‐500 analytical column was used to provide simultaneous anion exchange and reverse‐phase ion‐chromatography. Using 25 mM NaOH in 45% acetonitrile as eluent at a rate of 0.8 mL min−1, the analysis time was 10 min/sample. A complete recovery of total S from plant materials and with sulfur added as cysteine, methionine, glutathione, and sulfate is demonstrated. The method is simple, accurate, reproducible, and can be automated.
Potassium Utilization by No‐till Full‐Season and Double‐Crop Soybean
Authors: Coale F. J. , Grove H. J. 
Published: July 2010

AbstractAlthough K accumulation by soybean [Glycine max (L.) Merr.] has been studied extensively, data on differential K utilization by full‐season and double‐crop soybean are not available. Potassium utilization by no‐till soybean grown at two levels of soil K fertiliiy and two row widths was evaluated under full‐season and double‐crop planting dates. Plant component dry weight and K concentration were determined at growth stages R1, R5, and R7. For both planting dates, high soil K fertility resulted in elevated tissue K concentration and K accumulation in all plant parts at all three growth stages. At R1, double‐crop soybean tissue K concentrations were greater than that of full‐season soybean. At R7, double‐crop soybean leaf and abscised tissue K concentrations were lower than those of full‐season soybean, suggesting a disproportionately greater translocation of K out of the double‐crop soybean leaf during seed‐fill. At R7, seed K accounted for 64 and 38% of total plant K for low and high K fertilily regimes, respectively. seed IC at R7 was a constant proportion of total K accumulated for both full‐season and double‐crop planting dates. Row spacing did not alter shoot K concentration or accumulation for either planting date. Potassium accumulation rate was greatest between R1 and R5, was increased by high K fertility conditions, and was not different between full‐season and double‐crop planting dates except during the seed‐filling period when the fullseason soybean K uptake rate was greater. Full‐season soybean maintained a greater soil K uptake rate during seed‐fill while double‐crop soybean seed K supply was apparently more dependent on redistribution of K from other plant tissues.
General Model for Predicting Crop Response to Fertilizer
Authors: Johnson G. V. 
Published: July 2010

AbstractPredicting crop response to fertilizers is fundamental to determining fertilization profitability. This paper describes development of a general model to predict crop response to N, P, and K fertilizers. The Mitscherlich percent sufficiency concept and Bray mobility concept are the general underlying principles upon which the model is developed. Crop yields are projected within the limits of a maximum equal to the yield goal and a minimum calculated as a fraction of the yield goal based on percent sufficiency–calibrated P and K soil tests, and available mineral and organic N. Organic N contributions are estimated from algorithms developed to provide a means of indexing the degree to which crops in the past were grown in a N‐rich environment and easily mineralizable organic N accumulated. Output of the model generates N, P, and K response surfaces typical of those generally found in the literature. Evaluation of the quadratic P response components in the model indicate that a coefficient of 2 for the linear term and 1 for the squared term are good first approximations. Magnitude of P and K fertilizer responses is related directly to soil test value and amount of nutrient applied. Response to N fertilizer is large and nearly linear when the yield average is small compared to the yield goal. The response decreases and becomes more curvilinear as the yield average approaches the yield goal. The model is general enough to have broad application, yet allows for local specificity through use of the soil test and yield goal information.
Potato Uptake and Recovery of Nitrogen‐15‐Enriched Ammonium Nitrate from Periodic Applications
Authors: Roberts S. , Cheng H. H. , Farrow F. O. 
Published: July 2010

AbstractThere is a trend in potato (Solanum tuberosum L.) production to make repeated additions of N fertilizer in sprinkler irrigation water for an extended part of the season. More information is needed on scheduling (rate and timing) these N supplements. A 3‐yr study on the use of frequent supplements of 15NH4‐15NO3 by ‘Russet Burbank’ potato was conducted on Quincy loamy sand (mixed, mesic Xeric Torripsamment). The purpose of the experiment was to trace changes in the uptake and partitioning of 15N in vines and tubers from starter and periodic additions totaling 336 kg N ha−1. Labeled N fertilizer was sprayed on a different set of replicated potato plots according to the application schedule. Plant tissue samples were taken and analyzed regularly for labeled N uptake. Whole potato plants over the season recovered a maximum of 61 to 67% of the 15N‐enriched increments of fertilizer applied, as compared to a maximum of 42 to 54% partitioning of the labeled N in tubers at final harvest. Recovery of 15NO3 was significantly higher on the average than recovery for 15NH4. Furthermore, in many cases the average recovery was highest from labeled N applied during tuber bulking early in July, which suggests that this is a crucial time for maintaining adequate N fertility.