bluuebunny/crossref_metadata_2025_split huggingface dataset:
Central Appalachian Hill Land Pasture Evaluation Using Cows and Calves. I. Ordinary and Generalized Least Squares Analysis for an Unbalanced Grazing Experiment1
Authors: Burns J. C. , Giesbrecht F. G. , Harvey R. W. , Linnerud A. C. 
Published: July 2010

AbstractIn formal grazing trials, especially those involving cow‐calf test units, the land area needed and cost of initiation and operation limit the number of treatments simultaneously evaluated. Often it is desirable to terminate and add a new treatment or simply add a new treatment during the trial. The analysis of the resulting unbalanced data poses several difficulties. The objective of this paper was to evaluate a two‐step statistical procedure to analyze cow‐calf responses from an unbalanced grazing trial. Per animal and per hectare responses and pasture characteristics were obtained from a 6‐year study conducted in the Appalachian hill land region. Soils ranged from a Typic Hapludult to a mixed, mesic Hapludult. Pastures were a mixture of Kentucky bluegrass (Poa pratensis L.), white clover (Trifolium repens L.), and orchardgrass (Dactylis glomerata L.) and 12 agronomic or animal management treatments were evaluated. Some of the original treatments were deleted and new ones added, but not always on fields already in the study or in equal replication. The full 6‐year unbalanced data set contained two balanced subsets used to evaluate results from the two‐step analysis. The statistical procedure involved a fist step of estimating variance components for year and field effects. These were applied in a second step as a weighted adjustment through a generalized least squares analysis. The variance components, treatment mean adjustments and associated standard deviations from the two‐step analyses were compared with ordinary least squares (OLS) analyses where years were fixed effects and fields ignored (OLS1) or year and field effects were both ignored (OLS2). Year and field variances for cow and calf daily gains, pasture productivity estimates and pasture measurements from the 6‐year unbalanced data had similar magnitude and structure from the two‐step procedure compared with the two balanced data subsets. The residual error from OLS1 and OLS2 compared with the two‐step analysis were consistently larger. The two‐step analysis (unbalanced data) gave biologically rational adjustments of treatment means and offers much potential for use in experiments requiring high resources and where unbalance is likely for maximum treatment evaluation.
Soybean Water Status and Canopy Microclimate Relationships at Four Row Spacings1
Authors: Sojka R. E. , Parsons J. E. 
Published: July 2010

AbstractThere is little field data relating plant water status and canopy microclimate of determinate soybean [Glycine max (L.) Merr.] cultivars grown in humid environments. Also, few observations of these parameters have been reported for the period prior to complete canopy closure. A field study was conducted in South Carolina in 1979 to determine these basic relationships for two determinate soybean cultivars, Davis (Group VI) and Coker 338 (Group VIII) grown in 1.02, 0.76, 0.51 and 0.36‐m row spacings. The experiments were conducted on a Norfolk loamy sand (fine‐loamy, siliceous, thermic, Typic Paleudult). Thermistor‐determined leaf temperatures (TL) and ambient temperatures (TA) were highly correlated, and no significant improvement in the correlation resulted from treating row spacing or diurnal periods separately. Both TL and ΔT (TL – TA) were highly correlated with pressure chamber determination of xylem pressure potential (ΨX). Parallel leaf diffusive resistance (R5) was not highly correlated with any of the canopy microclimate or water status parameters observed. Atmospheric vapor pressure deficit (VPD) was correlated with ΔT. Xylem pressure potential was very highly correlated with leaf vapor pressure deficit (LVPD). No row spacing effect on Ψx was observed, but mean seasonal midday Ψx was 0.10 MPa lower for Coker 338 than for Davis (P≤0.001) and osmotic potential was 0.20 MPa lower for Coker 338 than for Davis (P≤0.01). The authors propose that the slope of ΔT vs. VPD may be influenced by high prevailing relative humidity and heating of the canopy from exposed soil between rows in the period prior to complete canopy coverage.
Nitrification of Anhydrous Ammonia Related to Nitrapyrin and Time‐Temperature Interactions1
Authors: Gomes S. L. , Loynachan T. E. 
Published: July 2010

AbstractThe effects of time and temperature, with and without nitrification inhibitor, were evaluated on the rate of nitrification for field‐applied anhydrous ammonia on a Webster clay loam soil (fine loamy, mixed, mesic Typic Haplaquoll) in central Iowa. The purpose of the study was to document factors influencing the production of oxidized N, forms of N more easily lost from the soil by leaching or denitrification. Anhydrous ammonia at 180 kg N/ha was applied at three application dates in the fall of 1979 (9 October, 27 October, and 14 November) and three application dates in the spring of 1980 (15 April, 2 May, and 25 June). Plots with and without 0.56 kg/ha nitrapyrin were established on each date. Ammonium was found to be concentrated within a 5‐cm radius of the injection zone. The accumulation of heat units (HU), calculated by the summation of temperature (°C) multiplied by time (days), was shown to have a negative correlation with recoverable NH4‐N and followed the equation: %NH4‐N = −0.07 HU + 76.4, R2= 0.84*, significant at the 0.05 level. Thus, much of the variability of recovered NH4‐N could be explained by a time by temperature interaction. This suggests that a grower's decision to apply anhydrous ammonia in the fall when soil temperatures reach a given level, commonly 10˚C, should be tempered by the date. In early fall, more time is available for nitrification to occur before freezing of the soil, and a greater conversion of NH4‐N to N03‐N would be expected. In the presence of a nitrification inhibitor, higher percentages of NH4‐N were recovered for a similar heat‐unit accumulation. Regression equations predicted an 84% recovery with 233 accumulated heat units in the presence of nitrapyrin, compared with a 60% recovery without nitrapyrin. For an equal percentage of NH4‐N recovery the following spring, a grower could apply anhydrous ammonia earlier in the fall if nitrapyrin was used. According to the equations developed in this study for the 1979‐1980 season, a 9 October application of anhydrous ammonia with nitrapyrin would have resulted in approximately a 70% NH4‐N recovery in the spring of 1980, compared with the same recovery for a 23 November application without nitrapyrin.
Maturity Effects on Genotype × Environment Interactions in Grain Sorghum1
Authors: Saeed Mohammad , Francis C. A. , Rajewski J. F. 
Published: July 2010

AbstractGenotype × environment (GE) interaction is an important consideration in plant breeding because of its effects on progress from selection. This study examines the effects of genotype maturity on GE interaction for grain yield and yield components. Fifty‐four grain sorghum [Sorghum bicolor(L.) Moench] genotypes included in three maturity groups, early, medium, and late, were evaluated in 48 environments across Nebraska and Kansas in 1978 and 1979. The soil ranged from sandy types (mixed, mesic Typic Ustipsamment) to intermediate types as represented by Typic Haplustoll, course‐silty, mesic and fine‐silty, mixed, mesic, Aridic Argiustoll, to clay loam at the opposite extreme (deep with high water holding capacity) as represented by fine, montmorillonitic mesic, Typic Argiuboll. In the analysis of variance combined over years and environments within year, genotype, genotype × year, and genotype × environment within year sums of squares were partitioned into components representing within and among maturity groups. More than half of the interaction effects sums of squares was attributed to differences among maturity groups. The GE interaction increased with an increase in duration of plant growth (maturity). Genotypes showed larger interaction with environments within year than with years, irrespective of maturity. The results suggest that a reliable evaluation of relative genotype performance can be made if the genotypes under test do not include a wide range of maturity. Minimizing differences in maturity among genotypes reduces GE interaction. Testing at more locations or environments at given locations should be done rather than testing in more years. For a desired level of precision, the amount of testing required for a set of genotypes with a wide range of maturity and long‐growth duration is greater than that required for genotypes with a narrow range of maturity and short‐growth duration. Increasing number of replications per test more than two, environments in a year more than eight, and years of testing more than two, was not effective in increasing efficiency in genotype evaluation, especially in early and medium maturing genotypes.
Leaf Area Development in Field‐Grown Soybeans1
Authors: Sinclair T. R. 
Published: July 2010

AbstractLeaf area is critical for crop light interception, and thereby has a substantial influence on crop yield. In this research an attempt was made to characterize the development of soybean [Glycine max(L.) Merr.] leaf area by examining the process in two phases. First, the rate of increase of plastochron index as a function of temperature was evaluated under field conditions. A total of seven cultivars was studied during three cropping seasons on Arredondo fine sand (loamy siliceous hyperthermic Grossarenic Paleudalf). A linear response was confirmed in the rate of increase in plastochron index to temperature with a base temperature of 9 to 11°C for most cultivars. Second, an allometric model for predicting plant leaf area from plastochron index was developed. The same medel with differing coefficients was found to work well for all cultivars. A simplified procedure for estimating the coefficients of the model was developed and found to result in good predictions of leaf area from plastochron index.
Zinc Nutrition Related to Critical Deficiency and Toxicity Levels for Sorghum1
Authors: Ohki K. 
Published: July 2010

AbstractSorghum [Sorghum bicolor(L.) Moench] production has increased in the Southeastern United States as a second crop in many double‐cropping systems. Guidelines are needed for Zn concentration in leaf blade tissue for the diagnosis and correction of Zn deficiency and toxicity problems. The Zn critical deficiency level (CDL) and critical toxicity level (CTL) are the minimum and maximum concentrations, respectively, associated with a 10% yield reduction from maximum yield due to Zn deficiency and toxicity. Sorghum was grown in nutrient solutions containing Zn concentrations ranging from 0.0 to 91.78 nmol L−1in 14 increments in the greenhouse. Individual blades were sampled at 49 days growth and analyzed for Zn concentration by atomic absorption spectrometry. The Zn CDL values in blades were 10, 10, 9, 13, and 24 µg g−1for blades 1 (top), 2, 3, 4, and 5 (bottom), respectively, as calculated from the exponential relationship of Zn concentration in blades and top dry weight. The Zn CTL values in blades were 64, 68, 80, 100, and 195 µg g−1in blades 1, 2, 3, 4, and 5, respectively. For tissue sampling to diagnose Zn deficiency and toxicity, blade 1 is recommended. The Zn CDL and CTL are 10 and 64 µg g−1, respectively, sampled at growth stage 2 and near maximum vegetative growth harvested at this time is expected if the Zn concentrations are within the CDL and CTL.
Estimating Absorbed Photosynthetic Radiation and Leaf Area Index from Spectral Reflectance in Wheat1
Authors: Asrar G. , Fuchs M. , Kanemasu E. T. , Hatfield J. L. 
Published: July 2010

AbstractSome plant growth models require estimates of leaf area and absorbed radiation for simulating evapotranspiration and photosynthesis. Previous studies indicated that spectral reflectance, absorption of photosynthetically active radiation (PAR), and leaf area index (LAI) are interrelated. The objective of this study was to establish a procedure by which spectral reflectance can be used to simultaneously estimate PAR absorption and LAI. A method is presented for estimating the quantity of absorbed PAR by wheat (Triticum aestivumL.) plants and their LAI based on the normalized difference (ND), transformation of the near infrared (ρn= 800 to 1100 nm) and red (ρr= 600 to 700 nm) canopy reflectances. The results, from a theoretical analysis and field measurements, indicated that ND correlates with the fraction of PAR absorbed by wheat canopies. Bare soil reflectance and scattering of near infrared radiation by foliage elements were the major factors that influenced the relation between ND and PAR absorption. The estimated PAR absorption values, based on the ND, and four classes of assumed leaf angles (45°, 60°, 75°, and spherical), were used to indirectly evaluate LAI of wheat for three different geographical locations. The standard deviation on mean predicted to measured LAI's for the three locations varied from 0.5 to 0.9 for a range of 0 to 6 LAI. The method is considerably less sensitive in predicting LAI above 6.0 since the sensitivity of ND to changes in LAI becomes small (<0.01), due to small changes in canopy reflectance.
Soil Testing, Foliar Analysis, and DRIS as Guides for Sugarcane Fertilization1
Authors: Elwali A. M. O. , Gascho G. J. 
Published: July 2010

AbstractFoliar analysis has been practiced widely in sugarcane (a complex trispecies hybrid of Saccharum) for planning and evaluation of fertilizer programs and harvest schedules. On the mainland of the USA, sugarcane farmers have traditionally relied on soil testing to plan fertilizer programs. Soil testing remains an excellent preplant practice but its reliability for the successive ratoon crops has been questioned. Results of foliar analyses are usually interpreted on the basis of the Critical Nutrient Level (CNL) approach. Recently, the Diagnosis and Recommendation Integrated System (DRIS) was introduced as an alternative approach for foliar diagnosis. The present study was conducted to evaluate the effectiveness of soil testing and foliar analysis interpreted by the CNL approach and by the DRIS as guides for sugarcane fertilization. Standard nutrient levels and DRIS norms were established for N, P, K, Ca, Mg, Fe, Mn, Zn, and Cu in the top visible dewlap leaf laminae of sugarcane. Comparison of the three methods was conducted in eight fields of ratoon sugarcane representing the major sugarcane soils in south Florida. Soil samples were collected in May and leaf samples in May, July, and September. Fertilizers were applied in May and July as indicated by each method. Foliar analysis interpreted by either method revealed a need for applying one or more micronutrient(s) to all fields, a practice which had not previously been recommended for ratoon sugarcane in Florida. Application of N was also recommended for the first time on Torry muck soil (euic, hyperthermic Typic Medisaprist) by foliar analysis using both methods. Fertilization according to the DRIS significantly increased both cane and sugar yields compared with those obtained when fertilization was guided by foliar analysis using the CNL approach or soil testing. Differences were not significant between foliar analysis using the CNL approach and soil testing. The high cane and sugar yields obtained by DRIS‐guided fertilization were attributed to the better nutrient balance as revealed by DRIS indices late in the season. Foliar analysis using the DRIS proved to be a better guide for fertilization of sugarcane than the soil testing method currently in use.
Effect of Planting Date and Plant Population on Sunflower Performance1
Authors: Miller B. C. , Oplinger E. S. , Rand R. , Peters J. , Weis G. 
Published: July 2010

AbstractSunflower (Helianthus annuus L.) is an alternate cash crop in the northern humid USA. Sunflower responds variably to planting date and plant population in different production areas. Field experiments were conducted for 3 years to determine the effect of planting date and plant population on sunflower seed yield and other plant characteristics under the humid growing conditions in the north central USA. In Exp. I, three planting dates, from early May to late June, were established with two hybrids at 30,000, 45,000, 60,000 and 75,000 plants ha−1 at Arlington (1978 to 1980) and Spooner (1978 to 1979), Wis. In Exp. II, two hybrids were established at three populations, 30,45, and 60,000 plants/ha, under irrigated and dryland conditions at Hancock (1978 to 1980), Wis. The soil types were silt loam (Typic Argiudoll) at Arlington, and sandy loam (Typic Udipsamment) at Spooner and Hancock. Planting in early and mid‐May at Arlington, and mid‐May at Spooner maximized seed yield, seed weight, seeds head,−1 oil concentration, oil yield, and test weight. Sunflower seed and oil yields were not influenced by plant populations ranging from 28,700 to 73,200 plants ha−1. Relatively constant yields were a consequence of reduced seed weight and seeds head−1 as plant population increased. The yield response of sunflower to increasing plant population, among planting dates and hybrids was more variable under the northern, cooler climate at Spooner. Yield and plant height were much higher under irrigated conditions on the sandy soils at Hancock. Although seed oil concentration under the dryland conditions at Hancock was 1.8% higher, the oil yield was 172 kg ha−1 lower, than under the irrigated conditions.
Tillage System × Planting Date Interactions in Corn Production1
Authors: Eckert D. J. 
Published: July 2010

AbstractLittle information is available concerning the effect of no‐tillage (NT) production on development of corn (Zea mays L.) through harvest, or on appropriate planting dates for NT corn. In this study, NT and conventional tillage (CT) (moldboard plow) corn were planted on a series of planting dates over a 3‐year period, on a moderately well‐drained Canfield silt loam (fine‐loamy, mixed, mesic Aquic Fragiudalfs) located at Wooster, Ohio. Under these conditions, tillage system had no effect on development or yield when data were averaged over 3 years. However, CT corn often silked earlier than NT corn under cooler conditions and yielded more in a wetter than normal year. No‐tillage corn silked earlier and yielded more than CT corn in a drier than normal year. Later silking did not result in wetter grain at harvest in NT corn, but often did so in CT corn. Date of planting had the same effect on yield in both tillage treatments.
Nonstructural Carbohydrates and Dehydration Tolerance of Blue Grama Seedlings1
Authors: Khan Sultan M. , Wilson A. M. 
Published: July 2010

AbstractBlue grama [Bouteloua gracilis (H.B.K. Lag ex Steud.] seedlings are susceptible to dehydration during warm dry winds, even when the seminal root has extended into a moist soil profile. The objective of this study was to determine relationships between total nonstructural carbohydrates (TNC) and dehydration tolerance of seedling crowns (lower 3‐cm of stem base). The greenhouse and controlled environment study included growth of seedlings for accumulation of TNC, use of shade and sunlight after shade to change TNC percentage in crowns, dehydration of crowns, and evaluation of the effects of dehydration treatments on tiller survival and production of adventitious roots. Soil was a fine‐loamy, mixed, mesic Aridic Argiustoll. Percent TNC in crowns from various shade and light treatments were as follows: control, 10.1; 2 days shade, 7.5; 4 days shade, 5.9; 4 days shade + 2 days light, 9.0; 4 days shade + 4 days light, 10.4. After dehydration treatments, the numbers of surviving tillers per pot in treatments receiving no shade (control), 2 days shade, 4 days shade, 4 days shade + 2 days light, and 4 days shade + 4 days light were 42, 22, 14, 33, and 42, respectively. Number of surviving tiller decreased with an increase in dehydration stress. Path coefficient analysis indicated a significant relationship (p < 0.01) between TNC and tiller survival (p = 0.35). Thus establishment and persistence of blue grama on semiarid lands may depend on maintenance of adequate levels of TNC.
Premature Flowering in Soybean Yield Reductions at Nonoptimal Planting Dates as Influenced by Temperature and Photoperiod1
Authors: Board J. E. , Hall W. 
Published: July 2010

AbstractThe optimum time for soybean [Glycine max (L.) Merr.] planting in the southeastern USA is from early May to early June. Planting at other times has consistently resulted in seed yield losses which have been blamed on premature flowering induced by short photoperiods. Objectives in this study were to characterize the photoperiod response of soybean cultivars commonly grown in the southeastern USA, determine if daylength differences between optimal and nonoptimal planting dates in the southeastern USA are great enough to cause premature flowering, determine the interaction of photoperiod and temperature factors on the length of the vegetative stage, and evaluate the ability of delayed flowering genotypes to avoid yield losses at nonoptimal planting dates. The studies were conducted in both growth chambers (to provide daylengths of 12 to 16 h and temperatures of 21 to 30°C) and in the field (Aquic Fragiudalf soil). Group V cultivars had smaller increases in vegetative period as daylength increased and had a longer daylength beyond which flowering did not occur compared to Group VI, VII, and VIII cultivars. The critical daylength using constant photoperiod durations for achieving an adequate vegetative period was determined to be between 14 and 14½ h in ‘Forrest’, ‘Centennial’, and ‘Tracy‐M’, while ‘Bedford’, ‘Davis’, ‘Ransom’, ‘Bragg’, and ‘Braxton’ had a critical photoperiod between 13½ and 14 h. Based on these studies, daylength encountered by soybeans planted early (e.g., early April) is short enough to cause premature flowering. Daylength encountered by some cultivars planted late (e.g., mid‐June) is not short enough to cause premature flowering. However, daylength is short enough to cause premature flowering in most cultivars at a July planting date. Field data supported these predictions. Evaluation of delayed flowering genotypes in photoperiod and field studies showed promise for avoidance of yield losses caused by short‐day induced premature flowering. Temperature photoperiod interaction studies showed that warm temperature (27°C) compared to cold temperature (21°C) decreased the time to first flowering and had its greatest effect under short rather than long days. This effect was greater in Group VI and VII cultivars compared to Group V cultivars.
Behavior of Steers Grazing Several Varieties of Tall Fescue During Summer Conditions1
Authors: Bond J. , Powell J. B. , Weinland B. T. 
Published: July 2010

AbstractFescue (Festuca arundinacea Schreb.) toxicosis during summer grazing is characterized by decreased tolerance to environmental stress. The purpose of this study was to determine if this reduced tolerance causes changes in the behavioral patterns of steers (Bos spp.) grazing fescue pastures during summer conditions as has been shown under other conditions of environmental stress and sickness. During a 3‐year experiment to measure chemical characteristics of four lines of tall fescue and to study physiological responses of steers grazing these fescue varieties, observers monitored the behavior of steers at 1300 h daily and during two 24‐h periods on 9 Sept. and 12 Oct. 1978. Categories with the highest frequency included grazing, lying in the field and shade, and standing in the field and shade. Steers on G1‐307 (an experimental line which contained a low level of perloline) showed symptoms of fescue toxicosis and grazed 20% less, laid in the field 4% less, and laid and stood in shade 8 and 17% more, respectively, than the steers that grazed ‘Kentucky 31’, ‘Kenhy’, and G1‐306 (high level of perloline). All steers spent less time lying in field and more standing in shade on 9 September than 12 October. Results suggest that the grazing behavior of steers varied as a function of variety of tall fescue grazed, particularly during periods of climatic stress.