bluuebunny/crossref_metadata_2025_split huggingface dataset:
AGSTATS—A Statistical Analysis Program for Simple Experiments
Authors: Karow Russell S. 
Published: July 2010

AbstractAGSTATS is a statistical analysis program that allows county agents and growers to analyze completely randomized and randomized complete block experiments with a maximum of 15 treatments, six replications, and no missing plots. The user selects the experimental design to be used and is then asked for the number and label of treatments and replications. A row (treatments) and column (replications) table for data entry is displayed. The program allows changes in table headings, replication and treatment labels, and data. Output is a summary table including means, LSD, and CV values that can be stored on disk, printed, or both. The program will recycle to allow additional data using the same design‐treatment‐replication information or the user can enter information for a new trial. The program runs on IBM‐compatible computers. While intended for an inexperienced data analysis audience, the program is also useful for quick analysis of small lab, greenhouse, or field experiments and as a teaching aid.
Intensifying Plant Density Response of Corn with Artificial Shade
Authors: Hashemi‐Dezfouli A. , Herbert S. J. 
Published: July 2010

AbstractCompetition among corn (Zea mays L.) plants for interception of photosynthetically active radiation (PAR) at high plant density can result in a reduction in kernel number per ear and complete ear barrenness. The response of field corn to long‐term shading as density increased was investigated. A single‐ear hybrid was grown at the Agricultural Experiment Station Farm, Univ. of Massachusetts, at three densities of 3, 7.5, and 12 plants m−2. Shading was provided by using black polypropylene fabric with 50% light penetration installed 44 d after emergence. The rate of apparent photosynthesis in ear leaves was reduced significantly by both increased plant density and shading. The reduction was attributed to reduced PAR in higher densities and shaded plots and to the decreased chlorophyll concentration measured in leaves of plants at high density in both ambient light and shaded plots. Tassel emergence was slightly delayed in high density and shaded plots. However, the time of silking was delayed significantly because of both high density and shading. Seven days after anthesis, 10% of plants in high densities and 50% of plants in shaded plots had no silk. The response of grain yield per unit area in ambient light to increasing density was parabolic. No increase in yield was obtained with density increase in the shaded plots. Shade reduced the number of productive ears per plant, and the number of kernels per row resulting in a 23 and 66% yield reduction in low and high plant densities respectively, when compared to ambient light. Weight per kernel was reduced 28% with increased plant density. Shading did not further decrease kernel weight. The number of kernel rows per ear was least sensitive to both high plant density and shading.
Corn Phosphorus and Potassium Uptake in Response to Soil Compaction
Authors: Dolan M. S. , Dowdy R. H. , Voorhees W. B. , Johnson J. F. , Bidwell‐Schrader A. M. 
Published: July 2010

AbstractSoil compaction by heavy axle load farm machinery can inhibit optimum plant growth. Uptake of essential nutrients, like P and K, is influenced by soil compaction. This study describes plant P and K accumulation from a compacted Webster (fine‐loamy, mixed, mesic Typic Haplaquolls) soil. Whole plant samples of corn (Zea mays L.) were collected at the 75% vegetative‐tassel (VT) stage from 0, 9, and 18 Mg axle load subsoil compaction treatments, each with secondary interrow surface soil compaction of 0‐ or 4.5‐Mg axle loads. Subsoil compaction reduced P and K uptake as much as 22% during seasons when June and July rainfall was less than average. Subsoil compaction of 18 Mg did not consistently reduce P and K uptake more than did 9 Mg subsoil compaction. Surface soil compaction also reduced P uptake, but to a lesser extent than did subsoil compaction. Overall P and K uptake, across all treatments, was enhanced when June and July precipitation was average or wetter than the 30‐yr average.
Estimation of Solar Radiation Data Missing from Long‐Term Meteorological Records
Authors: Hook J. E. , McClendon R. W. 
Published: July 2010

AbstractSolar radiation has a direct effect on plant growth and, thus, is used in most crop growth models. At most locations in the USA, though these measurements have been made only in recent years. At Tifton, GA, a 53‐yr (1938–1990) record was available with meteorological observations consisting of maximum/minimum temperature, precipitation, and pan evaporation. Only during the last 15 yr was solar radiation data available. To allow us to use these data to evaluate realistic scenarios for drought occurrence studies, we developed a method to estimate daily global solar radiation. Using a 13‐yr record of meteorological observations with solar radiation, a regression equation was developed to determine daily solar radiation from maximum and minimum air temperature, pan evaporation, precipitation, and calculated extraterrestrial radiation. A random component was added to express the variability associated with the unmeasured degree of cloudiness. The radiation estimate had the same variances and means as observed data and an overall correlation of 78%. The 53‐yr record with estimated solar radiation represents an intermediate step between computer generated radiation scenarios and fully measured data. The approach presented here should help to complete long‐term weather records so that crop growth and water balance models can be applied to historical data.
A Modular Structure for Crop Simulation Models: Implemented in the SIMPOTATO Model
Authors: Hodges Tom , Johnson Scott Lee , Johnson Brad S. 
Published: July 2010

AbstractA highly modular structure has been developed for crop growth simulation models and implemented in the SIMPOTATO model, a model based on the standards of the IBSNAT (International Benchmarks Sites Network for Agrotechnology Transfer) project. The model structure features top‐down design, modularity, high cohesiveness, loose coupling, and data hiding. SIMPOTATO is composed of (i) an upper level module to run the model, (ii) an experiment selection module, (iii) an initialization module, (iv) a simulator module, (v) the crop and soil processes module, (vi) a start/stop module, (vii) a report writing module, and (viii) a graphic display module. Each module is composed of one or more subroutines and functions. Such a modular structure facilitates transferring improvements between models, combining models into multi‐crop models and crop/pest models, and modifying models for new applications.
Cultural Factors for Minimizing Bermudagrass Invasion into Tall Fescue Turf
Authors: Brede A. D. 
Published: July 2010

AbstractTall fescue (Festuca arundinacea Schreb.) is becoming increasingly popular for turf in areas where bermudagrass [Cynodon dactylon L. (Pers.)] has traditionally been grown. Volunteer bermudagrass can be a serious weed problem in tall fescue lawns, and presently there are no reliable herbicides to eradicate bermudagrass without injury to the fescue. The purpose of this study was to examine multiple cultural factors to see if a combination of treatments might be used to prevent bermudagrass invasion into fescue turf. Cutting height (19 and 57 mm), fescue cultivar (‘Kentucky‐31’ and ‘Mustang’), fescue seeding rate [2100, 12 900, and 34 400 pure‐live seeds (PLS) m−2], fertilization rate (49 and 244 kg N ha−1yr−1), and source of bermudagrass introduction [seed, rhizomes, or stolons (clippings)] were examined in this 2‐yr field study performed on Kirkland silt loam soil (fine, mixed, thermic, Udertic Paleustolls) in central Oklahoma. No bermudagrass invaded plots that were seeded to the two higher fescue seeding rates and mowed at the higher cutting height. The greatest number of bermudagrass originations (6 crowns m−2) and amount of stolon coverage (42%) occurred in plots of Mustang seeded to the lowest seeding rate, mowed at the lower cutting height, and fertilized at the heavier rate, with seed as the source of bermudagrass introduction. In conclusion, if tall fescue is managed like bermudagrass turf (closer mowing, higher fertilization), then the stand may eventually give way to invading bermudagrass.
Irrigating and Liming Alfalfa on Coastal Plain Soil
Authors: Morris D.R. , Caldwell A.G. , Corkern D.L. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) stands do not persist for longer than 2 or 3 yr in many regions of the southern USA. A 3‐yr experiment was conducted to determine if alfalfa yield and stand persistence could be improved by irrigating and liming. Water management treatments were no irrigation and spinkle irrigation with about 25 mm of water when soil moisture reached approximately 50% of available water. Dolomitic lime treatments included 0 lime, 2.2 Mg lime ha−1 applied before planting, and 4.4 Mg lime ha−1 applied before planting, and 2.2 Mg time ha−1 applied every year. Soil samples were taken and analyzed for pH, exchangeable Ca, Mg, and Al and available Mn. In addition, plant density was monitored. Annual dry matter yields averaged 13, 10, and 3 Mg ha−1 in 1987, 1988, and 1989, respectively. The progressive decrease in seasonal yield over time was due to a decline in plant population density from an average of 191 to 26 plants per square meter between Years one and three of the study. Dry matter yield was not changed by irrigation, but decreased by an average of 0.9 Mg ha−1 when lime was not applied. Crop annual dry matter yield showed a positive correlation with soil Ca, Mg, and pH and a negative correlation with soil Al. Growing conditions resulting from lime application and irrigation should have been favorable for alfalfa production; therefore, stand reduction was probably not due to acid condition or drought stress in the surface soil.
Yield and Quality of Silage Corn as Altered by Johnsongrass Infestation
Authors: Mueller J. P. , Lewis W. M. , Green J. T. , Burns J. C. 
Published: July 2010

AbstractDairy and beef producers in the southern piedmont region of the USA with limited land often grow corn (Zea mays L.), after corn, for silage even though stands gradually become infested with johnsongrass [Sorghum halepense (L.) Per.]. The objective of this study was to quantify the influence of johnsongrass infestation on the yield and quality of corn grown for silage. Seven field trials were conducted over a 6‐yr period in the piedmont region of North Carolina on clayey, kaolinitic, thermic, Typic Hapludult soils. Corn was planted each year into johnsongrass‐infested sites. Herbicides were used to produce johnsongrass‐free plots and plots where johnsongrass was the only weed present. Additionally, to assess the influence of johnsongrass infestation level on the subsequent silage quality, physical mixtures of corn and johnsongrass forage were made which represented an infestation range from 0 to 100% by weight. In five of seven trials, corn forage yield was significantly increased with johnsongrass control. Where johnsongrass was not controlled, corn plant population was reduced by 13% and silage quality, estimated by in vitro dry matter disappearance (IVDMD), was reduced by 8 to 21%. Silage IVDMD decreased linearly 2.37 g kg−1 (r2 = 0.95, P < 0.001) for each percentage unit increase in johnsongrass infestation by weight.
Nitrogen Management for Spring Wheat Grown Annually on Zero‐Tillage: Yields and Nitrogen Use Efficiency
Authors: Campbell C. A. , Zentner R. P. , Selles F. , McConkey B. G. , Dyck F. B. 
Published: July 2010

AbstractSoil testing laboratories require predictive equations that provide accurate fertilizer recommendations to improve economic return to producers and reduce the risk of environmental pollution. Snow management by cereal trap strips and fertilizer N management involving rates, placement, and timing of application were studied in a 9‐yr experiment on a Swinton Loam (Aridic Haploboroll) in southwestern Saskatchewan. Spring wheat (Triticum aestivum L.) was grown annually using zero‐tillage management. Stepwise regression with backward elimination was used to develop the following relationship: Y = −781 + 3.11 WU + 6.88 FN − 0.053 FN2 − 0.33 SN2 + (0.23 SN × WU) − (0.25 SN × FN) + (0.035 FN × WU) + (0.00083 SN × FN × WU) + (1.60 Yr × SN) − (0.53 Yr × FN) R2 = 0.91, P=0.001, n = 1248), where Y = grain yield (kg ha−l), WU = estimated water use (mm), SN = available soil N (kg ha−1), FN = rate of fertilizer N (kg ha−1), and Yr = number of years of study. Water use was available spring soil water in the 0‐ to 1.2‐m depth plus 1 May to 31 July precipitation, and SN was NO3‐N in 0‐ to 0.6‐m depth, measured in the fall. The regression accurately predicted yields of wheat for an 8‐yr zero‐tillage study carried out on similar soil nearby. Fertilizer N placement (seed placed, deep band, broadcast) influenced grain yields more than timing, but in 5 of 9 yr neither factor was significant. Response to fertilizer N decreased with years, presumably because the available N supplying power of the soil improved under no‐till management with adequate fertilization. Efficiency of available N use [grain wt/(SN + FN)] varied from 4 to 41 kg grain kg−1 N, being directly related to WU and generally to SN, but inversely to FN rate.
Use of Stability Analysis for Long‐Term Soil Fertility Experiments
Authors: Raun W. R. , Barreto H. J. , Westerman R. L. 
Published: July 2010

AbstractLong‐term fertility experiments with replications are often statistically analyzed as split plots in time. Years are often shown to be significantly different and the inconsistency of treatment effects over years enters into significant year‐by‐treatment interactions which are difficult to interpret. The objectives of this study were to evaluate long‐term fertility experiments by stability analysis and relative stability and to observe possible benefits of these analyses to complement conventional analysis of variance procedures. Stability analysis which is the linear regression of treatment yield on the location/year environment mean yield was performed on long‐term wheat (Triticum aestivum) and corn (Zea mays L.) fertility trials. Stability analysis on wheat data from the Magruder Plots, indicated that beef manure applications (269 kg N ha−1) responded poorly compared to the NPK treatment when environment means were low (<2.0 Mg ha−1) and visa versa when environment means were high (>2.0 Mg ha−1)‐ Similarly, anhydrous ammonia applied as sidedressing in an irrigated corn experiment at Mead, NE, was found to be superior to urea‐ammonium nitrate applied either pre‐plant or sidedressed when environment means were less than 8.0 Mg ha−1. Stability analysis provided a simple method of interpreting significant year‐by‐treatment interactions detected in analysis of variance models from these longterm experiments. Stability analysis may also be useful for multilocation experiments and continuous site experiments where treatments are applied to the same plot year to year. However, stability analysis may be misleading when employed on continuous site experiments where autocorrelations are present year to year.
Cool Night Temperatures Alter Leaf Starch and Photosystem II Chlorophyll Fluorescence in Cotton
Authors: Warner Donn A. , Burke John J. 
Published: July 2010

AbstractCotton (Gossypium hirsutum L.) growth and reproduction are sensitive to cool temperatures, but few studies are available on specific metabolic responses to low temperature stress. We studied the relationship between starch levels and Photosystem II (PSII) function in cotton plants grown in growth chambers to determine if low temperature stress at night alters metabolic processes during the day when temperatures are optimal. Predawn starch levels in fully expanded leaves were three to four times higher on an area basis, and PSII chlorophyll fluorescence was 43 to 54% lower in leaves of two varieties of cotton (T25 and Paymaster HS26, averages for three plants of each variety) when grown with a day/night temperature of 28/20 °C, compared with plants grown at a constant temperature of 28 °C. Cotton plants that were grown at a constant 28 °C had 4.4 (T25, n = 3) to 6.6 (HS26, n = 3) times more starch on a leaf‐area basis after exposure to one night at 20 °C. When cotton plants that were grown with a day/night temperature of 28/20 °C were exposed to one night at 28 °C, starch was depleted to levels found in control plants that were grown at a constant 28 °C. The response of chlorophyll fluorescence was reciprocal to that of leaf starch when night temperature was changed. Shading, to reduce starch in six plants of each variety grown with 20 °C night temperatures to levels found in plants grown with 28 °C night temperatures, resulted in increased PSII chlorophyll fluorescence of 200%. We conclude that a night temperature of 20 °C caused an accumulation of leaf starch that was associated with reduced PSII function, even when plants experienced optimal temperatures during the day.
Defoliation and Plant Density Effects on Maize Selected for Reduced Plant Height
Authors: Edmeades G. O. , Lafitte H. R. 
Published: July 2010

AbstractSelection for reduced plant height in maize (Zea mays L.) has been accompanied by a reduction in stem volume and in stem nonstructural carbohydrate (SNSC) reserves, which may result in increased instability of grain yield when plants are exposed to stress during grain filling. This possibility was examined when cycles 0, 6, 12, and 18 of a tropical maize population selected recurrently for reduced height were grown in four environments at 3.5 and 6.7 plants m−2 and defoliated by removing all but five, all but three, or no leaves 7 d after 50% silking. Per‐cycle changes were observed in undefoliated plots for stem biomass (−0.116 Mg ha−1), grain yield (0.052 Mg ha−1), optimum plant density for grain yield (0.14 plants m−2), and harvest index (0.009). Lodging declined from 39 to 10% with 18 cycles (C18) of selection. The reduction in SNSC in C18, compared with C0, was 0.66 Mg ha−1. Defoliation increased the per‐cycle reduction in final stem biomass to −0.146 Mg ha−1, but reduced grain yield and harvest index equally in all cycles of selection. At 7 d after silking, SNSC was correlated with final plant height (r = −0.66**, 16 df) and with final kernel number per plant (r = 0.48*, 16 df). Reduction in plant height increased stability of grain yield by reducing lodging and by increasing tolerance to stresses occurring near flowering.
Aluminum Effects on Calcium Uptake and Translocation in Wheat Forages
Authors: Huang J. W. , Grunes D. L. , Kochian L. V. 
Published: July 2010

AbstractThe effects of Al on Ca transport could influence Ca accumulation in plants. Low forage Ca concentrations may cause hypocalcemia, a Ca deficiency syndrome of ruminants. Solution culture experiments were conducted in a growth chamber to examine the effects of Al (5–50 μM on uptake and translocation of Ca (45Ca) in winter wheat (Triticum aestivum L.) cultivars (Al‐tolerant Atlas 66 and Al‐sensitive Scout 66). Three‐day‐old seedlings, grown either in a CaCl2 solution (0.1 or 1.0 mM) or in a complete‐nutrient solution, were used. For plants grown in CaCl2 solution, addition of 5 μM Al significantly decreased Ca uptake and translocation in Scout 66, but not in Atlas 66. Higher levels of Al (20 and 50 μM) decreased Ca uptake and translocation much more in Scout 66 than in Atlas 66. For plants grown in complete‐nutrient solution, Al (5–50 μM) exposure for up to 6 h had little effect on Ca uptake and translocation in either cultivar. This may be due to the reduction in Al3+ activities in the external solution, as well as lowered Al3+ activities near the root‐cell plasmalemma. When roots were exposed to Al for 24 h, Ca uptake and translocation were decreased significantly in Scout 66, but were little affected in Atlas 66. The percentage of Ca translocated to the shoots was significantly decreased by Al in Scout 66, but not in Atlas 66. These results suggest that Al inhibits both Ca uptake and translocation in Scout 66, but inhibits primarily root Ca uptake in Atlas 66 (and only at higher Al levels). It appears that the use of Al‐tolerant cultivars of wheat forages on acid soils could be important for maintaining proper Ca nutrition of grazing animals.
Minirhizotron Wheat Root Data: Comparisons to Soil Core Root Data
Authors: Box J. E. , Ramsuer E. L. 
Published: July 2010

AbstractA nondestructive, quick, and efficient root measurement technique that quantifies root dynamics is critical to understanding environmental effects on rooting. The objective of this study was to compare roots of three cultivars of soft red winter wheat (Triticum aestivum L.) observed in minirhizotrons with those washed from soil cores. Minirhizotron determinations were root count (Ca, count cm−2) and root length (La, cm cm−2) per unit area; soil core determinations were root length (Lv, cm cm−3) and root dry weight (Wv, mg cm−3) per unit volume. Growth stages studied were double ridge, early boot, milk, and soft dough. Analysis of variance showed that growth stage and soil depth were significant for Lv, Wv, Ca, and La. Cultivar was significant at early boot and milk growth stages for Ca. Linear regression of Lv, Wv or La as a function of Ca provided highly significant slope and, except for Wv, intercept values. Statistically, Ca was the most discriminating minirhizotron measurement parameter.
Growth and Nutrient Uptake Parameters in Sorghum as Influenced by Aluminum
Authors: Baligar V. C. , Schaffert R. E. , Dos Santos H. L. , Pitta G. V. E. , De C. Bahia Filho A. F. 
Published: July 2010

AbstractSorghum[Sorghum bicolor (L.) Moench] is the fifth most important cereal crop in the world. The majority of soils on which sorghum is grown are acidic, and production on such soils is limited by high levels of Al and Mn, and deficient levels of Ca, Mg, and P. A greenhouse experiment was conducted to evaluate differences in growth and uptake (U), influx (IN), and transport (TR) of nutrients by 40 sorghum genotypes at three levels of soil Al saturation. Growth of shoots and roots and nutrient uptake parameters were affected by soil Al saturation, genotypes, and their interactions. Growth and uptake parameters were used to separate the genotypes into most efficient and least efficient categories at various levels of soil Al saturation. Shoot nutrient U, IN, and TR were positively correlated (P < 0.01) with shoot and root dry weight, and inversely related (P < 0.01) to soil Al saturation and shoot Al concentration. Our greenhouse technique appears to be a reliable method for separating genotypes into Al‐tolerant and intolerant types. Genotypes used in the study showed intraspecific genetic diversity in growth and uptake, influx, and transport of essential elements. Therefore, selection of acid‐tolerant genotypes and further breeding of Al‐tolerant cultivars is feasible in sorghum.