bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scales: a Computer Program to Convert among Three Developmental Stage Scales for Wheat
Authors: Harrell D. M. , Wilhelm W. W. , McMaster G. S. 
Published: July 2010

AbstractThe Haun, Feekes, and Zadoks‐Chang‐Konzak developmental stage scales are often used to report phenological information for wheat (Triticum aestivum L.) development. Agronomists familiar with one of these scales may have only a passing acquaintance with developmental scales other than the one they consider most appropriate for their purposes. This makes review and interpretation of the literature more difficult. Although wheat development models often report phenological results, they generally use no more than one scale. For these reasons, and because there is not a simple numeric correspondence among the three scales, a computer program to convert among them is a useful tool. SCALES is a three‐module FORTRAN program that relates the three scales based on published descriptions. The interactive user interface module requests an input scale value and minimal additional information, which the conversion module uses to determine values for the remaining two scales via a dichotomous key. The output module writes the conversion results to the monitor. SCALES may be used independently for comparing phenological data based on different developmental scales, or the conversion module may be incorporated into computer models to provide output of developmental stage information for the simulation.
Validation of Salinity Crop Production Functions Obtained with the Triple Line Source Sprinkler System
Authors: Royo A. , Aragüés R. 
Published: July 2010

AbstractTraditional methods of screening crops under field conditions for salt tolerance produce low selection efficiencies at a relatively high cost; consequently, more practical and reliable methods need to be developed. We evaluated the reliability of salinity crop production functions obtained with a triple line source (TLS) sprinkler system, the reproducibility of the results from different years and site locations within the TLS, and the minimum plot size per cultivar that allows for consistent results. Ninety‐six percent of the 154 ECaw (electrical conductivity of the applied water)‐grain yield response functions obtained from 6 yr of field experiments with the TLS had significant correlation coefficients (P < 0.05), and 77% of the standard errors (SE) of the estimated EC50 (EC of the applied water that reduces yield by 50%) values were <2.0 dS m‐1. The EC50 and SE values of four barley (Hordeum vulgare L.) cultivars sown at the center and at the far end of the TLS plot indicate that the response functions were independent of location within the TLS. The EC50 and SE values of eight barley cultivars grown in different years indicate nonsignificant differences (P > 0.05) in 79% of the 29 comparisons performed. The EC50 values of four barley cultivars grown in hill plots and in two‐row, three‐row, and six‐row plots did not differ statistically (P > 0.05). With a typical 30‐ by 60‐m TLS system, elemental two‐row 1.2‐m‐long plots, and 10 saline treatments, 120 salinity crop production functions can be developed. Hence, this system is a reliable and practical field method for developing salinity‐crop production functions and screening for salt tolerance.
Nitrogen Fertilization Effects on Planting Stock Characteristics and Establishment Performance of Dwarf Elephantgrass
Authors: Rusland G. A. , Sollenberger L. E. , Jones C. S. 
Published: July 2010

Abstract‘Mott’ elephantgrass (Pennisetum purpureum Schum.) is a high‐quality tropical forage that is vegetatively propagated using stems or stem cuttings. Mott is more difficult to establish than tall elephantgrass, and a better understanding is needed of management factors that affect its establishment. During 1987 through 1989, field studies were conducted on an Adamsville fine sand (hyperthermic, uncoated, Aquic Quartzipsamment). Objectives were to determine the effect of N fertilization of planting stock nurseries on chemical and physical characteristics and establishment performance of Mott stems, and to determine if relationships exist between planting stock characteristics and establishment performance. Nitrogen rates were 0, 50, 100, 200, 300, and 400 kg ha−1, and treatments were replicated twice for measurement of stem characteristics and three times for establishment performance. Stem length (31.0–40.5 cm), mass (10.4–14.8 g per stem), N concentration (8.9–16.0 g kg−1), N content (0.09–0.24 g per stem), and total nonstructural carbohydrate (TNC) content (0.97–1.33 g per stem) increased linearly with increasing N rate. Measures of establishment performance generally increased with increasing N rate in 1987 and 1989, years for which rainfall was near or above normal during the time when planting stock was growing. Drought during this period in 1988 resulted in lower values for most stem characteristics and for measures of establishment performance. Highest correlation coefficients (0.53–0.60) were observed between number of emerged shoots per row and the stem characteristics, length, mass, and TNC concentration and content. These data indicate that N fertilization of Mott nurseries (≥200 kg ha−1) and soil moisture during growth of planting stock are critical to subsequent establishment performance of planted stems, and that stem characteristics are correlated with establishment performance.
Deriving Fertilizer Recommendations with a Flexible Functional Form
Authors: Sain Gustavo E. , Jauregui Mario A. 
Published: July 2010

AbstractGeneral fertilizer response models are useful to derive robust recommendations for farmers who face different circumstances. This paper shows that a flexible functional form such as the transcendental can be applied to develop both agronomically and economically sound recommendation tables using a set of soil test, climate, and management variables. Data from thirty‐eight experiments on wheat response to N and P in the Humid Pampa, Argentina, were used to build a general response model that incorporates the initial levels of soil test measures (NO3‐N and Bray‐1 P), rainfall from sowing to maturity, and previous crop. The economic analysis was performed for relevant nutrient/grain price ratios ro = 8.0 and rp = 18.3 for N and P, respectively. A table of fertilizer recommendations for wheat was derived for different combinations of rainfall expectations, previous crop, and soil test values. The following results were obtained: (i) the estimated model not only accounted for a significant percentage of the total variability in the dependent variable (InY), with R2 =0.56, P = 0.01, but it also gave coefficients with signs in conformity with agronomic expectations; (ii) the economic optima for N (N*) and P (P*) are compatible with the range of optima computed with per‐site economic analyses; (iii) N* and P* increased as rainfall increased; (iv) N* was lower for wheat after soybeans than for wheat after maize; (v) N* was higher for smaller values of soil N, while P* was practically unaffected by soil N; and (vi) P* was higher for smaller values of soil P, while N* was affected by soil P, with a pattern that depended on both previous crop and rainfall. Similar tables can be derived for groups of farmers under different economic circumstances (i.e., different input/output price ratios).
Timing of Furrow Irrigation Termination for Determinate Soybean on Clay Soil
Authors: Heatherly Larry G. , Spurlock Stan R. 
Published: July 2010

AbstractIrrigation commencing at or near beginning bloom (R1) and continuing during reproductive development of determinate soybean [Glycine max (L.) Merr.] grown in the southern USA in dry years increases seed yield. The number of irrigations between the first and last irrigation event can influence the direct costs of irrigation; however, the optimum time to stop irrigation in relation to crop maturity has not been identified. ‘Leflore’ (1987–1990) and ‘A5980’ (1988–1990) determinate cultivars were grown on Sharkey clay (very‐fine, montmorillonitic, nonacid, thermic Vertic Haplaquept) at Stoneville, MS, to determine the effect of timing of last furrow irrigation on seed yield, yield components, yield increase, and net returns. All irrigation treatments within a cultivar were started at R1 (beginning bloom) or later. One treatment was dropped from the sequence with each successive furrow irrigation event through R6 (full seed). Irrigation applied through mid‐R5 (seed‐filling period) during a dry year produced the greatest seed yield increase of 1855 kg ha−1, which was 610 kg ha−1 greater than the yield of the treatment terminated at R4 (full pod), and equal to the yield of the treatment terminated at R6. Yield increases due to irrigation during wet years were smaller or nonexistent. In all cases, increased number of seeds was the sole contributor to increased yield. In the dry years, irrigation terminated at either mid‐ to late‐R2 or mid‐R5 produced the greatest yield increase per unit of irrigation water, but irrigation continued into the seedfill period and then terminated produced the highest net return. These results indicate that furrow irrigation of soybean grown on a cracking clay soil in dry years should be continued through mid‐R5 to achieve maximum seed yield and net returns.
Timing of the First Irrigation in Corn and Water Stress Conditioning
Authors: Jama Ahmed Omar , Ottman Michael J. 
Published: July 2010

AbstractDelaying the first irrigation is thought to encourage root growth and to condition crop plants for stress later in the growing season. We tested this common practice for corn (Zea mays L.) grown under arid conditions in Tucson, AZ, in 1989 and 1990. In field studies conducted on an Agua sandy clay loam (coarse‐loamy over sandy, mixed, thermic Typic Torrifluvent), the first irrigation was applied at the 2‐leaf, 4‐leaf, or 6‐ to 8‐leaf stages, followed by irrigation or water stress at anthesis. Delaying the first irrigation did not encourage root growth but actually restricted it in 1989. Seasonal water use was decreased from an average of 796 mm to 705 or 652 mm if the first irrigation was delayed from the 2‐leaf to the 4‐leaf or 6‐ to 8‐ leaf stages, respectively. Timing of the first irrigation did not affect yield in 1989, or in 1990 if irrigations were withheld at anthesis. However, grain yield was decreased from 830 to 693 g m−2 and total plant yield was decreased from 2490 to 2185 g m−2 when the first irrigation was delayed past the 2‐leaf stage in 1990 and the crop was well‐watered at anthesis. Delaying the first irrigation of corn, with 148 mm (1989) and 170 mm (1990) plant available water in the top 1.5 m of soil at the beginning of the season, did not appear to condition the crop for water stress later in the season in an arid environment, but may substantially decrease yield if adequate water is available for the remainder of the growing season.
Errors in Measuring Absorbed Radiation and Computing Crop Radiation Use Efficiency
Authors: Gallo Kevin P. , Daughtry Craig S. T. , Wiegand Craig L. 
Published: July 2010

AbstractRadiation use efficiency (RUE) is often a crucial component of crop growth models that relate dry matter production to energy received by the crop. RUE is a ratio that has units g J−1, if defined as phytomass per unit of energy received, and units J J−1, if defined as the energy content of phytomass per unit of energy received. Both the numerator and denominator in computation of RUE can vary with experimental assumptions and methodologies. The objectives of this study were to examine the effect that different methods of measuring the numerator and denominator have on the RUE of corn (Zea mays L.) and to illustrate this variation with experimental data. Computational methods examined included (i) direct measurements of the fraction of photosynthetically active radiation absorbed (ƒA), (ii) estimates of ƒA derived from leaf area index (LAI), and (iii) estimates ƒA derived from spectral vegetation indices. Direct measurements of absorbed PAR from planting to physiological maturity of corn were consistently greater than the indirect estimates based on green LAI or the spectral vegetation indices. Consequently, the RUE calculated using directly measured absorbed PAR was lower than the RUE calculated using the indirect measures of absorbed PAR. For crops that contain senesced vegetation, green LAI and the spectral vegetation indices provide appropriate estimates of the fraction of PAR absorbed by a crop canopy and, thus, accurate estimates of crop radiation use efficiency.
Manual and Digital Line‐Intercept Methods of Measuring Root Length: A Comparison
Authors: Farrell Richard E. , Walley Frances L. , Lukey Adele P. , Germida James J 
Published: July 2010

AbstractThe manual line‐intercept (MLI) method is widely accepted as the standard method of estimating root length. Recently, however, semiautomated systems employing a digital line‐intercept (DLI) method have been developed. Although the DLI method is said to represent a significant time savings over the MLI method, comparisons between the two methods are relatively scarce. This study was conducted to determine and compare root length estimates obtained using manual and digital line‐intercept methods and to evaluate different methods of preparing root subsamples for analysis. Roots were collected from spring wheat (Triticum aestivum L.) inoculated with three different plant growth‐promoting rhizobacteria and a vesicular‐arbuscular mycorrhizal fungus. Subsamples were cut from bulk root systems before or after they had been dried, and root lengths were estimated using both the MLI and DLI methods. Although the DLI and MLI methods yielded highly correlated results (r2 = 0.880***) when the subsamples were dried before being cut, the DLI method consistently underestimated root lengths and could not distinguish between inoculant effects. This was attributed to the inability of the imaging system to resolve small pieces of shattered root. When subsamples were prepared from fresh root material, the number of small root fragments was minimized; the two methods yielded highly correlated results (r2 = 0.943***) and both methods were equally adept at distinguishing significant differences between inoculant effects. Accurate root length estimates can be obtained using the DLI method with subsamples prepared from fresh roots in one‐ to two‐thirds less time than can be achieved with the MLI method.
Modeling the Occurrence of Reproductive Stages after Flowering for Four Soybean Cultivars
Authors: Grimm Sadi S. , Jones James W. , Boote Kenneth J. , Herzog D. C. 
Published: July 2010

AbstractSoybean growth and yield models require good predictions of vegetative and reproductive development stages, as a function of specific environmental variables. Parameters for predicting R5 (beginning of seed growth) and R7 (physiological maturity) dates of four soybean cultivars were estimated for a development rate model. R5 is predicted by accumulating a daily rate of development, which depends on night length and temperature, starting at Rl (flowering) until a threshold is reached. Daily development rate is computed by a multiplicative relationship containing two linear‐plateau functions: one for describing the variation in development rate with night length under optimal temperature and the other describing variation with temperature under optimal night length. The downhill simplex method was used to estimate phenological parameters for each cultivar, minimizing the error sum of squares between observed and simulated dates of R5 occurrence. The same type of model and methodology was used to estimate parameters for R7 prediction, but beginning at R5 until a threshold is reached. The results indicate that as plants develop from V1 (first true leaf) to R7 they become more responsive to photoperiod and less sensitive to temperature. Differences among cultivars with respect to optimal night length tend to diminish as the plants approach physiological maturity; with respect to temperature, the reverse happens. The optimal temperature for reproductive development varied between 25 and 29 °C, without great differences among cultivars of differing maturity, but with a slight increasing trend from V1 toward R7.
Performance Comparisons of Conventional and Laboratory‐Scale Alfalfa Hay Bales in Small Haystacks
Authors: Coblentz Wayne K. , Fritz John O. , Bolsen Keith K. 
Published: July 2010

AbstractField trials designed to study the storage of moist hay have often been plagued by uncontrollable factors such as weather. A system for making laboratory‐scale (10.3 by 10.8 by 13.4 cm) hay bales was evaluated in two trials. In the first experiment, three conventional small square bales of alfalfa (Medicago sativa L.) were prepared in the field at each of seven different combinations of moisture and density. One bale was randomly selected to be used as the forage source for laboratory‐scale bales of the same density. Laboratory bales were incubated between the two remaining conventional bales. Bale types were compared for maximum temperature, 30‐d average temperature, degree days > 30 °C, visual mold, dry matter (DM) recovery, total nitrogen (N), acid‐detergent fiber (ADF), neutral‐detergent fiber (NDF), and acid‐detergent‐insoluble nitrogen (ADIN). Laboratory bales generally remained different (P < 0.05) from parent conventional bales for most temperature‐related traits. Agreement between bale types was better for most quality analyses. In an effort to improve relative performance between bale types, a second experiment was conducted, in which the laboratory bales were prepared at 1.0, 1.3, 1.6, and 2.0 times the density of the conventional bales. Results showed improved agreement between laboratory bales of elevated densities and conventional bales for most temperature traits. Acid‐detergent‐insoluble N levels for laboratory bales were greatly affected by bale density. High‐density laboratory bales had significantly greater ADIN fractions than conventional bales, particularly in the high moisture treatment. These results implicate bale density as an important factor in damage to alfalfa proteins by the Maillard reaction.
Sensitivity of Winter Wheat Phyllochron to Environmental Changes
Authors: Cao Weixing , Moss Dale N. 
Published: July 2010

AbstractThe effect of environmental changes on the rate of leaf emergence in wheat (Triticum aestivum L .) must be understood to accurately simulate the development of the crop canopy. We determined the phyllochron for ‘Stephens’ winter wheat plants in growth chambers at two constant temperatures (10 and 18 °C) at a daylength of 14 h and at two constant daylengths (8 and 18 h) at a temperature of 20 °C, and for plants transferred between the two temperatures and between the two daylengths at the first‐, second‐, third‐, and fourth‐ leaf stages. The phyllochron of all plants transferred from low to high temperature increased to that of plants kept continually at the high temperature. The phyllochron of plants transferred from high to low temperature at the one‐leaf stage was identical with the phyllochron of plants kept continually at the low temperature, but was intermediate between that of the high and low temperatures for transfers at the second‐, third‐, or fourth‐leaf stage. The phyllochron of plants transferred from short to long days decreased to values identical to those plants kept continually at the long daylength. The phyllochron of all plants transferred from long to short daylengths increased to values equal to or greater than that of plants kept continually at the short daylengths. Thus, plants adapted to either temperature or daylengths environments that favor rapid leaf emergence in real time had less capacity to utilize a less favorable environment for leaf growth than plants that were kept continually in the less favorable environment. The results help explain why the phyllochron is often constant for a particular field planting where plants are subject to seasonal changes in temperature and daylength.
DIALLEL: A Microcomputer Program for the Simulation and Analysis of Diallel Crosses
Authors: Burow Mark D. , Coors James G. 
Published: July 2010

AbstractA microcomputer program has been developed to be used as a teaching tool in quantitative genetics classes and as a means of analyzing real data from diallel crosses. The first part of the program, the simulation module, is of use as a teaching tool, offering students the opportunity to examine the ramifications of the underlying genetic and statistical assumptions of diallel mating designs. In particular, the program illustrates the difficulty in obtaining reliable estimates of genetic components of variance when employing a restricted number of parents. Using user‐entered values for the population mean, the number of parents, and genetic, environmental, and error variances, the program generates and analyzes multiple sets of data. The user can experiment by altering the parameters to test different strategies to cope with the difficulties inherent in the diallel mating design. The second module allows the analysis of real‐world experiments made in any of four diallel mating designs. The user may enter and correct data in the program itself, or import data as ASCII files from other programs. The program prints an analysis of variance table, and tables of means by variety and cross, heterosis, general and specific combining abilities, and genetic components of variance and their standard errors.
Seedling Growth as Affected by Seed Weight in Common Vetch
Authors: Qiu J. , Mosjidis J. A. , Williams J. C. 
Published: July 2010

AbstractGrowth pattern of seedlings is important for any species to achieve successful establishment. Growth chamber experiments were conducted to study the relationships between seed weight and usage of cotyledonary reserves and growth rates of major seedling components and to determine the changes in relative importance of cotyledonary reserves and newly developed photosynthetic tissues on seedling growth in common vetch (Vicia sativa L.). Seedlings from three seed‐weight groups of ‘Warrior’, PI 284563, and ‘Cahaba White’ were grown in growth chambers at a temperature of 28/12°C under complete darkness and light–dark cycle (13/11 h) conditions. Seedlings from heavier seeds utilized cotyledonary reserves (UCR) at a faster rate; however, conversion efficiency of cotyledonary reserves (CECR) into plant tissue was the same regardless of seed weight. Hence, the advantage of heavy seeds lies in their higher content of cotyledonary reserves and on their ability to provide energy more rapidly to the growing seedlings. Seedlings from heavier seeds had greater rates of elongation, accumulation of leaf area and shoot, leaf, and root dry weights than those from light seeds. Thus, heavier seeds produce seedlings with a higher growth capacity in common vetch. Cotyledonary reserves supported heterotrophic seedling growth for ≈7 d after emergence (DAE) under dark conditions. However, cotyledonary reserves had little importance in subsequent growth once the first tetrafoliolate leaf emerged at 5 DAE for light‐grown seedlings. Thus, the emergence of the first tetrafoliolate leaf marks the transition between heterotrophic and autotrophic seedling growth.