bluuebunny/crossref_metadata_2025_split huggingface dataset:
OILCROP‐SUN: A Development, Growth, and Yield Model of the Sunflower Crop
Authors: Villalobos Francisco J. , Hall Anthony J. , Ritchie Joe T. , Orgaz Francisco 
Published: July 2010

AbstractCrop simulation models are important tools for agronomic management strategy evaluation, particularly under rainfed conditions. This paper describes the structure and testing of OILCROP‐SUN, a process‐oriented model of the sunflower (Helianthus annuus L.) crop. The model simulates organ biomass and N content, leaf area index, and soil water and N balances with a daily time step. Daily weather data, soil physical and chemical characteristics, and initial contents of water and N are required inputs. Three cultivar‐specific parameters synthesize crop responses to temperature and photoperiod during development, and two cultivar‐speciflc parameters define potential grain number per capitulum and potential kernel growth rate. Tested against independent data sets, the model generated good predictions of the durations of the sowing‐emergence (range 7 to 32 d; root mean square error [RMSE], observed vs. simulated: 3.7 d) and emergence‐anthesis phases (range 52 to 146 d; RMSE between 2.9 and 4.3 d, depending on the cultivar). The model also simulated seasonal crop biomass and leaf area dynamics for irrigated and rainfed crops sown at two densities satisfactorily, as well as aerial biomass (range 5 to 15 t ha−1; RMSE 1.7 ha−1) and grain yield at maturity (range 1.0 to 6.2 t ha−1; RMSE 0.8 t ha−1) for irrigated and rainfed crops sown at a range of population densities (0.5 to 10 plants m−2). We conclude that OILCROP‐SUN can be used to simulate biomass and grain yields over a wide range of conditions.
Whole‐Plant Physiological and Yield Responses of Maize to Plant Density
Authors: Cox Wiliam J. 
Published: July 2010

AbstractModern compared with older maize (Zea mays L.) hybrids tolerate more plant density stress, but more information is required on how modern hybrids interact with plant density. Field experiments were established in 1991 (warm‐dry) and 1992 (cool‐wet) to evaluate whole‐plant physiological, dry matter (DM), and grain yield responses of four commercial hybrids at low (4.5 plants m−2), medium (6.75), and high (9.0) plant densities. As plant density increased, leaf CO2 exchange rates (CER) declined 10 to 20% under mild and 20 to 30% under warm dry conditions. Compared with the high plant density, the low plant density had a 40% lower leaf area index from midvegetative to early grain filling, which offset higher photosynthetic efficiency, resulting in lower crop growth rates during vegetative development and 25% less DM accumulation at silking. When averaged across hybrids, the low plant density averaged 15% lower DM and grain yields than the high plant density. Hybrid ✕ plant density interactions were observed for DM and grain yields. The more prolific hybrid showed mostly linear DM and grain yield responses to plant density, whereas a single‐eared hybrid showed quadratic responses in both years. Another single‐eared hybrid, which did not respond to density, had low leaf CER at all densities, a reduction in kernels per plant at the medium density, and increased barrenness at the high plant density in 1991. Apparently, modern hybrids interact with plant density, regardless of growing conditions, and some modern hybrids do not tolerate density stress in dry years.
Management of Tropical Legume Cover Crops in the Bolivian Amazon to Sustain Crop Yields and Soil Productivity
Authors: Luna‐Orea Pedro , Wagger Michael G. 
Published: July 2010

AbstractThe trend to shorter natural fallow periods in shifting agriculture calls for management alternatives to accelerate nutrient accumulation and aid in weed control. Substituting cover crop‐based managed fallows is one possibility. Our objectives were to (i) quantify nutrient accumulation by three tropical legumes [Canavalia ensiformis (L.) DC.; Desmodium adscendens (Sw.) DC.; and tropical kudzu, Pueraria phaseoloides (Roxb.) Benth.] grown as managed fallows for 12 and 18 mo, (ii) evaluate the effect of residue management (burning vs. not burning) on the efficient use of nutrients by the subsequent rotational crops rice‐cowpea‐rice [Oryza sativa L.‐Vigna unguiculata (L.) Walp.‐O. sativa], and (iii) determine the effect of commercial fertilizer on maintaining crop yields. The study was conducted at two sites (Typic and Aquic Dystropepts) in the Chapare region of Bolivia. Total aboveground nutrient contents of the cover crops, across sites and duration of managed fallow, ranged from 41 to 391 kg N ha−1, <1 to 27 kg P ha−1, 5 to 191 kg K ha−1, 3 to 136 kg Ca ha−1, and 7 to 47 kg Mg ha−1. Averaged across sites and residue management, grain yields for the first rice crop after a 12‐mo managed fallow were highest with pueraria (1.65 Mg ha−1), followed by canavalia (1.38 Mg ha−1) and desmodium (0.65 Mg ha−1). Slashing and burning resulted in a mean rice (1st crop) yield increase of 137% compared with slash only. Cowpea yield was less affected by treatment variables than rice, due perhaps to N2 fixation. For the last rice crop, there were no grain yield differences for any of the variables studied. Nutrient uptake differences were most evident with the first rice crop, and were influenced primarily by residue management. Compared with slash only, and averaged across sites for the first rice crop, slashing and burning fostered a whole‐plant increase of approximately 18 kg N ha−1, 3 kg P ha−1, 24 kg K ha−1, 4 kg Ca ha−1, and 3 kg Mg ha−1. Soil chemical properties were only marginally affected by any variable. Shorter fallow periods with legume cover crops can produce adequate yields of annual crops. Longer cropping periods than we used are likely to require lime and fertilizer to sustain crop production.
Turfgrass Quality, Growth, and Water Use Influenced by Salinity and Water Stress
Authors: Dean Dorothy E. , Devitt Dale A. , Verchick Linda S. , Morris Robert L. 
Published: July 2010

AbstractLimited water resources in the arid southwestern USA have created greater interest on the part of municipalities to utilize nonpotable waters in urban areas. Research was conducted to assess the feasibility of using a perched saline aquifer as an alternative irrigation source for turfgrass. Two line‐source irrigation gradients, one using municipal water with an EC of ≈ 1.1 dS m−1 and the other using saline aquifer water blended with municipal water to an EC of 6.0 dS m−1, were established to impose a salinity and/or water deficit gradient on tall fescue (Festuca arundinacea Schreb. ‘Monarch’) and an improved common bermudagrass (Cynodon dactylon L. ‘Numex Sahara’). Yield was found to be highly correlated with actual evapotranspiration (ETa) (r = 0.92, P < 0.001 for bermudagrass; r = 0.83, P < 0.001 for tall fescue), regardless of how the stress was imposed. Relative ETa (ratio of ETa to maximum ETa under municipal irrigation) values as a function of the summation of the leaf‐to‐air temperature differences also indicated no distinguishable change in stress response based on water quality (r = 0.94, P < 0.001 for tall fescue; r = 0.86, P <0.001 for bermudagrass). Relative turf color and percent cover remained unchanged if the ratio of irrigation volume to potential evapotranspiration (I/ETo) remained above species‐specific threshold values of 0.80 for tall fescue and 0.65 for bermudagrass. Below these thresholds, cover and color declined linearly, with differences due to water quality treatment in tall fescue but with no differences due to water quality treatment in bermudagrass.
Genotype of Wheat and Barley Affects Light Penetration and Wild Oat Growth
Authors: Lanning Susan P. , Talbert Luther E. , Martin John M. , Blake Thomas K. , Bruckner Philip L. 
Published: July 2010

AbstractCereal breeders have selected for traits that confer resistance to diseases and insects, with the goal of stabilizing yield potential and reducing inputs. The possibility exists that, by selecting for growth habits that impede weed development, cultivars can be developed with increased tolerance to weed infestations. Our objective was to determine whether wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) lines differ in their ability to prevent penetration of light into interrow spaces and suppress wild oat (Avena fatua L.) growth. Based on our results, significant genotypic variation exists within winter and spring wheat and spring barley for the amount of sunlight allowed to penetrate to interrow spaces. A negative correlation existed between height and light penetration in four of seven nurseries studied. Six barley lines and six spring wheat lines, of similar heights but allowing different amounts of light penetration, were tested for suppression of wild oat growth. Barley was a much better competitor with wild oat than wheat was, allowing approximately one‐half the wild oat biomass and seed production. Barley lines allowed approximately 43% less light penetration than wheat. Significant variation for wild oat growth variables also existed among lines within the crops. High positive correlations of light penetration with wild oat growth existed within barley, suggesting that lines may be selected to contribute to integrated wild oat management.
Superiority of Winter Sowing over Traditional Spring Sowing of Chickpea in the Mediterranean Region
Authors: Singh Kharag B. , Malhotra Rajinder S. , Saxena Mohan C. , Bejiga Geletu 
Published: July 2010

AbstractChickpea (Cicer arietinum L.), when traditionally grown as a springsown crop in the Mediterranean region, often suffers from heat and moisture stress, resulting in low and unstable yields. In contrast, sowing the crop in winter with cultivars tolerant to cold and to ascochyta blight [caused by Phoma rabiei (Pass.) Khune & J.N. Kapoor; syn. Ascochyta rabiei (Pass.) Lab.] minimizes the effects of terminal heat and drought stress and increases and stabilizes productivity. Therefore, a study was conducted with the objective of assessing the comparative seed yield advantage of winter over spring sowing in Mediterranean environments. Nineteen to 23 ascochyta blight‐resistant and cold‐tolerant breeding lines were compared in winter and spring sowing for 10 yr (1983–1993) at three locations in Syria and Lebanon. The set of lines used in this study differed each year. Averaged over 10 yr, winter‐sown chickpea produced 70% (692 kg ha−1) more seed yield than the spring‐sown crop. The longer growing period of winter‐sown chickpea resulted in higher biomass production, which contributed mainly toward increased seed yield. The yield potential of lines sown during winter was approximately 4000 kg ha−1, and yields were more stable than in the spring‐sown crop. The correlation between seasonal rainfall and seed yield was positive and significant in both seasons. In 1988–1989, when the Tel Hadya site experienced severe drought, the springsown crop resulted in virtually no seed yield, whereas the winter‐sown crop produced an average yield of 542 kg ha−1 by a partial escape of the severe drought. Winter‐sown plants were taller than those in the spring sowing, permitting harvesting by combines. Because of these advantages, winter sowing of chickpea is gaining popularity in the Mediterranean region.
Factors Affecting Maize Forage Quality Development in the Northeastern USA
Authors: Crasta Oswald R. , Cox William J. , Cherney Jerome H. 
Published: July 2010

AbstractTopographical features in the northeastern USA result in temperature and soil water differences between locations of close proximity. Dairy producers frequently inquire how these differences affect forage quality of maize (Zea mays L.). Field experiments were established in 1990 and 1991 at two locations and two planting dates to evaluate temperature and soil water effects on neutral‐detergent fiber (NDF), lignin, and in vitro dry matter digestibility (IVDMD). Whole‐plant IVDMD at harvest (R5 stage) had correlation coefficients (r) of −0.61 with NDF and −0.63 with lignin concentration at silking. Also, IVDMD had r = −0.90, −0.72, and 0.75 with NDF, lignin, and grain content, respectively, at the R5 stage. Stover lignin concentration and grain content explained 83% of the variability in whole‐plant IVDMD at the R5 stage. In the dry 1991 growing season, IVDMD was higher and fiber components were lower than in the wetter 1990 season. Locations, which had average temperature differences of 3.5°C from the eighth‐leaf (V8) to R5 stage, did not affect forage quality in 1990, but the cool location in 1991 had somewhat higher IVDMD and lower fiber components than the warm location. Nevertheless, regression analysis indicated that temperature did not contribute significantly to IVDMD variability and contributed only a small portion to NDF variability at harvest. In contrast, a calculated water deficit index value explained 74%o f the variability in IVDMD at early grain‐fill and 61% at harvest. Clearly, maize forage quality in this study was associated more with soil water differences than with temperature differences.
Environmental Adaptation of Long‐Juvenile Soybean Cultivars and Elite Strains
Authors: Tomkins Jeffrey P. , Shipe Emerson R. 
Published: July 2010

AbstractA long‐juvenile (LJ) trait that delays flowering under short‐day conditions has been incorporated into adapted soybean [Glycine max (L.) Merr.] germplasm. Little is known about the performance of recently developed LJ cultivars and elite strains as influenced by planting systems typical of the southeastern USA. Therefore, a field study was undertaken using two LJ cultivars and four elite LJ Florida strains at Blackville and Pendleton, SC. Planting dates were early (late April), normal (late May), and late (late June), in 1993 and 1994. The LJ genotypes exhibited neither genotype × planting date nor genotype × location interactions for seed yield or seed quality, indicating consistency of genotype performance across environments. Although variation among LJ genotypes for yield was not detected, all four elite strains all ranked higher in yield than the two cultivars. Maturity varied among LJ genotypes but seed yield did not, indicating the possibility of developing LJ genotypes that have relatively short life cycles and high seed yield. Additionally, LJ genotypes were compared with two conventional cultivars: Maturity Groups (MG) IV, V, and VI at early plantings; MG V, VI, and VII at normal plantings; and MG VI, VII, and VIII at late plantings. As planting date was delayed, growth and agronomic responses of LJ genotypes became similar to those of successively later conventional cultivars. The LJ genotypes were similar in yield to conventional cultivars in maturity groups V to VIII across planting dates, but had 56% higher yields than MG IV cultivars at the early planting. Seed quality ratings of LJ genotypes were 54 and 23% better than MG IV and V cultivars, respectively, at the early planting. In general, LJ genotypes showed superior photoperiodic adaptation to different planting date environments.
Grazing Sheep and Cattle Together or Separately: Effect on Soils and Plants
Authors: Abaye Azenegashe O. , Allen Vivien G. , Fontenot Joseph P. 
Published: July 2010

AbstractDifferences in grazing behavior suggest opportunities to improve forage use when cattle and sheep graze in the same pasture, but a better understanding of their effect on soils and plants is needed. Angus cows (Bos taurus) with calves and ewes (Ovis aries) (1/2 Dorset, 1/4 Finn, 1/4 Rambouillet crossbred) with lambs grazed Kentucky bluegrass‐white clover (Poa pratensis L.‐Trifolium repens L.) pastures from spring until autumn in a study of the effects on soils and plants of grazing cattle and sheep together and separately. The experiment was a randomized block design with three replications conducted during 3 yr. There were 6 cow‐calf pairs per replication of cattle alone and 6 ewes with 11 lambs per replication of sheep alone. For the mixed‐grazed pastures, there were 6 cows plus 6 ewes, each with their respective offspring, per replication. Grazing sheep alone increased soil bulk density (1.47 vs. 1.38 g cm−3), extractable soil P (140 vs. 80 kg ha−1), and percentage bluegrass (36 vs. 25%), but decreased percentage white clover (3 vs. 10%) compared with grazing cattle alone. Grazing sheep and cattle together resulted in soil bulk density and extractable soil P of 1.45 g cm−3 and 115 kg ha−1, respectively. Grazing sheep and cattle together resulted in a higher B horizon soil pH (6.7 vs. 6.4 and 6.5) and percentage organic mater (1.9 vs. 1.5 and 1.7) than where cattle or sheep grazed alone, respectively. Percentage bluegrass and white clover present in the sward where both animal species grazed was 37 and 5%, and there were fewer forbs (12%; P < 0.08) than when cattle or sheep grazed alone (18 and 15%, respectively). Grazing both animal species together appeared to have beneficial effects on several botanical composition and soil characteristics over grazing cattle and sheep in separate pastures.
No‐Till Corn Response to Crop Rotation and In‐Row Residue Placement
Authors: Janovicek Ken J. , Vyn Tony J. , Voroney Robert P. 
Published: July 2010

AbstractEnhanced corn (Zea mays L.) yield responses to rotation in no‐till systems may be due to the types and amounts of surface‐placed plant residue. Research in 1989, 1990, and 1995 evaluated no‐till corn yield response to various preceding crops and examined whether in‐row residue removal affected no‐till corn response to rotation crops. The soil was an imperfectly drained loam (medium, mixed, weakly to moderately calcareous Typic Hapludalf). The preceding crops were: corn harvested for grain or whole‐plant silage; hard red spring wheat (Triticum aestivum L.); barley (Hordeum vulgare L.); red clover (Trifolium pratense L.) cover crops, following barley, that were killed by spraying either 3 wk (early‐kill) or 1 d (late‐kill) prior to corn planting; canola (Brassica napus L.); and soybean [Glycine max (L.) Merr.]. In‐row residue was either retained while planting or cleared using planter‐mounted, notched‐disk row cleaners. Clearing in‐row cover crop residue increased early‐season corn growth and was associated with yield increases of 0.61 Mg ha−1 (8%) following early‐killed red clover and 0.43 Mg ha−1 (6%) (P = 0.10) following late‐killed red clover. In 2 of 3 yr, corn yields following early‐killed red clover were similar to following soybean and greater than following grain corn, provided that in‐row residue was cleared. Following the other crops, grain yield response to clearing in‐row residue was smaller and less consistent over years. Preceding cropping affected early‐season corn growth, with the largest plants at 5 wk after planting following either soybean or silage corn and the smallest following either red clover or grain corn. In 2 of 3 yr, when preceding crop effects on grain yield were statistically significant, yields following either soybean or spring wheat were more than 1.05 Mg ha−1 (16%) higher than after grain corn. That yield increase occurred regardless of in‐row residue placement. Removing corn stover by harvesting as silage increased corn yield by 0.86 Mg ha−1 (12%) over yield following grain corn. During 1995, corn yield following silage corn was less than after soybean, canola, barley, or wheat; thus, no‐till corn yield response to rotation is not exclusively due to the presence of surface‐placed stover. In‐row residue placement and preceding cropping practices affected in‐row soil temperature, but this could not totally account for the treatment effects on early‐season corn growth and yields.
A Computer Program for Geostatistical and Spatial Analysis of Crop Model Outputs
Authors: Thornton Philip K. , Booltink Harry W. G. , Stoorvogel Jetse J. 
Published: July 2010

AbstractWell‐tested computer simulation models of the growth, development, and yield of annual crops are being used for a wide range of purposes, including the prediction of impacts of different management practices and land use systems on food production, farmers' profitability, and the environment. Presentation and interpretation of simulation results can be significantly enhanced through the linking of models with software that allows spatial visualization. Many users of crop simulation models, however, are located in institutions in developing countries where resources are particularly limited. Computer software to perform a variety of spatial analyses was written, which can be run on modest hardware without the need for costly third‐party software. The software is an integral part of the Decision Support System for Agrotechnology Transfer (DSSAT), a comprehensive crop simulation model and data system, but can also be run in a stand‐alone mode. Users can run spatial simulation experiments and then analyze the results using (i) a geostatistical module to interpolate maps and produce probability surfaces from a network of data points and (ii) a utility that calculates agronomic and economic output statistics from model simulations and maps the results as polygons. The suite of modules, which runs on an IBM‐compatible personal computer, interfaces with some widely used third‐party GIS software, and the mapping facility enables users to export and import images to a number of common file formats.
Ontogenetic Evaluation of Grain Yield and Time to Maturity in Barley
Authors: Dofing Stephen M. 
Published: July 2010

AbstractHigh grain yield and early maturity are desirable characteristics in many regions in which barley (Hordeum vulgare L.) is grown. However, negative correlation between these traits makes their joint improvement difficult. Previous research quantifying the contribution of traits to grain yield has not included their effects on time to maturity, and often has not included important developmental traits related to time to maturity. The purpose of this research was to quantify the determination of grain yield and time to maturity in barley, using a model that included developmental traits such as leaf number, phyllochron, and grain fill rate. A genetically diverse group of 24 barley genotypes was grown for three years at Palmer, AK, and significant causal relationships determined using path analysis and stepwise regression. Longer vegetative periods (time to heading) resulted in higher grain yield, but longer heading‐to‐maturity periods had no effect on grain yield. Faster grain fill rate resulted in higher grain yield and shorter grain filling period. In environments similar to these, the competing objectives of high grain yield and acceptably early maturity were realized by cultivars with relatively long preheading periods and relatively short reproductive periods, without exceeding the critical level of early maturity required by growers. Longer preheading periods appear necessary to develop an adequate number of kernels per spike and sufficient number of leaves to provide photoassimilate during grain fill. These results provide breeders additional insights for decisions involving choice of germplasm and selection criteria in breeding programs.