bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cultivation, Cultivar, and Crop Age Effects on Sugarcane
Authors: Glaz B. , Ulloa M. F. , Parrado R. 
Published: July 2010

AbstractA practice that may allow farmers to reduce field cultivations is the use of cultivars that have vigorous growth rates early in the growing season. In sugarcane (a complex hybrid of Saccharum spp.) culture, this practice can be disadvantageous to sugarcane processors if these vigorous cultivars have lower sugar concentrations (SC) than the less vigorous cultivars. The objective of this research was to determine the effects of different levels of cultivation on yield characteristics of sugarcane cultivars with varying growth potentials and SCs, from the plant‐cane through the second‐ratoon crop. An experiment with four cultivation levels and three cultivars, representing slow‐growth rate/high SC, moderate‐growth rate/moderate SC, and fast‐growth rate/low SC types was conducted in a field infested primarily by short or prostrate weeds. Stalk heights and stalk counts were measured in the plant‐cane and second‐ratoon crops. Yields of Mg ha−1 of cane (MHC), SC and Mg ha− of sugar (MHS), were measured from the plant‐cane through the secondratoon crop. Although there were significant differences among the cultivars and among levels of cultivation for MHC, SC, and MHS, there were no important relative differences among cultivars across levels of cultivation for any of these characteristics. There were important differences in cultivars and levels of cultivation across crops. The most important conclusions were that cultivar growth rate did not influence number of cultivations necessary to attain maximum yields, and the greatest benefits from cultivating throughout the three‐crop cycle occurred in the last crop.
A Detrimental Interaction of Subsoil Aluminum and Drought Stress on the Leaf Water Status of Soybean
Authors: Goldman I. L. , Carter T. E. , Patterson R. P. 
Published: July 2010

AbstractDrought and subsoil Al are major concerns which face soybean [Glycine max (L.) Merr.] producers in the southeastern USA. However, the interaction of these two factors is not clearly understood. This study was designed to characterize the combined effect of these two stress factors on soybean water status. A greenhouse experiment was conducted, with two levels of subsoil Al saturation (6 and 71%), and two levels of drought stress (watered and unwatered). A split plot experimental design with three replications was employed. Soil treatments were applied via a soil layering technique using topsoil of a Goldsboro sandy loam (fine‐loamy, siliceous, thermic, Aquic Paleudult). The top layer in all pots consisted of the unamended topsoil. In the lower layer, highly contrasting Al saturation levels were obtained by amending one half of the pots with Al2(SO4)3. Data were collected during a 14‐d moisture stress treatment imposed at podfilling (R3). Traits measured were leaf water potential, relative water content, transpiration, and diffusive resistance. A detrimental interaction between subsoil Al and drought was observed in all traits measured. Plants grown in the presence of both stress factors had lower levels of leaf relative water content and water potential, and a lower transpiration rate than predicted additively by independent stress factors. In general, subsoil Al had much greater effects on leaf water status in drought‐stressed soybean plants than in the wellwatered plants. These results suggest that hindered root growth in highly Al‐saturated subsoils may have limited the ability of the plant to withstand drought. Soybean producers in regions characterized by drought and subsoil Al should consider the incorporation of Altolerant germplasm into management systems. Field studies including water stress as a variable should be interpreted with regard to this interaction, if soil A1 is present.
Least Significant Differences for Combined Analyses of Experiments with Two‐ or Three‐Factor Treatment Designs
Authors: Carmer S. G. , Nyquist W. E. , Walker W. M. 
Published: July 2010

AbstractMany agronomic experiments with complete factorial treatment designs are conducted in two or more environments. If at least one of the treatment factors is qualitative, the combined analysis may appropriately include pairwise comparisons of various treatment means averaged over environments. Heretofore, however, formulae for estimation of the variances of pairwise mean differences, which are needed for the calculation of least significant differences (or other mean separation procedures), have not been available in either the agronomic or statistical literature. The main purpose of this paper is to provide the formulae for estimation of these variances so that researchers can use them in testing the significance of differences among various treatment means averaged over environments. Emphasis is given to combined analyses of series of experiments in which the effects of experiments are considered to be random; individual experiments are assumed to have complete factorial treatment designs involving either two or three factors of which at least one is qualitative. All treatment effects, including main effects and interactions, are considered to be fixed effects. Formulae applicable to commonly used experimental designs are presented for the estimation of variances for the five categories of pairprise mean differences in two‐factor treatment designs and the 19 categories of pairwise mean differences in three‐factor treatment designs. Experimental design considerations and the implications of assuming random (versus fixed) experiment effects as well as the structure of the treatment × experiment interactions are studied. Pooling portions of the treatment × experiment interaction with error mean squares are considered, and suggestions are given for cases where some of the treatment factors are quantitative rather than qualitative.
Soybean Cultivar Response to Reduced Tillage Systems in Northern Dryland Areas
Authors: Deibert E. J. 
Published: July 2010

AbstractInformation on response of soybean [Glycine max (L.) Merr.] cultivars to reduced tillage systems in northern dryland areas is limited. A 4‐yr field study (1984 to 1987) was conducted to evaluate the effect of tillage system, weed control method, and cultivar maturity on soybean seed yield variables. An early and a late‐maturing soybean cultivar were grown on a Fargo clay (fine, montmorillonitic frigid Vertic Haplaquoll) on established tillage plots. Tillage systems included conventional (moldboard plow) and three reduced tillage systems (sweep, intertill, and no‐till) with herbicides or herbicides plus cultivation for weed control. Climatic conditions resulted in differences among years in seed yield, seed weight, seed moisture, seed oil concentration, and seed oil yield. These seed variables were not significantly influenced by tillage system, weed control method, or cultivar maturity when grown in rotation with barley (Hordeum vulgare L.), but showed significant interactions. Cultivation for weed control depressed seed yield and weight of only the early cultivar. Early plant water stress (June and July) lowered yield of the early cultivar more than the late cultivar. Early cultivar no‐till yields (1240 kg ha−1) were greater than tilled system yields (average 1070 kg ha−1), while late cultivar yields were similar among systems (average 1420 kg ha−1). An early maturing cultivar performed similarly to a late‐maturing cultivar irrespective of tillage system unless early plant water stress was encountered. Fall application of granular herbicide provided good weed control, but cultivation for weed control was not beneficial for the yields parameters measured.
Rice Response to Waterlog‐Tolerant Green Manures
Authors: Morris R. A. , Furoc R. R. , Rajbhandari N. K. , Marqueses E. P. , Dizon M. A. 
Published: July 2010

AbstractChemical N fertilizers are usually applied to modern rice (Oryza sativa L.) cultivars, but yield responses are obtained from green manuring as well. To be considered as a viable alternative to chemical N fertilizer in tropical Asia, however, green manures must tolerate the ephemeral waterlogging that precedes rice cultivation. Experiments on an Aeric Tropaqualf soil during three early wet seasons determined green manure N accumulation in 60 d or less, and rice grain yield response to it. In the first experiment (1983), cowpea [Vigna unguiculata (L.) Walp.] and Sesbania cannabina [(Retz.) Poir.] were grown 24, 36, and 48 d before incorporation. Nitrogen accumulation was greatest (79 kg N ha−1) in 48‐d S. cannabina. Accumulation in cowpea was apparently depressed by waterlogging. Rice grain yield response to green manure N was unaffected by location of green manure cultivation (in situ vs. transported from a nearby field). In the second (1984) and third (1985) experiments, Sesbania sp. were flooded during the last 25 d of growth to assure early wet–season waterlogging. Mean N accumulation in flooded S. rostrata (Brem. and Obrem.), which nodulates on its stem, was 90 kg ha−1 in 48 d and 164 kg ha−1 in 60 d. Nitrogen accumulations in nonflooded S. rostrata were 128 kg ha−1 in 48 d and 198 kg ha−1 in 60 d. Accumulation in a Nepalese S. cannabina cultivar averaged 84% of that in S. rostrutu. Rice grain yield response was a function of green manure N regardless of species or age. Both S. rostrata and S. cannabina tolerate waterlogging and accumulate sufficient N in less than 60 d to increase rice yields more than 2 Mg ha−1.
No‐Till Winter Wheat Production on the Canadian Prairies: Timing of Nitrogen Fertilization
Authors: Fowler D. B. , Brydon J. 
Published: July 2010

AbstractThe introduction of a practical snow management system, which uses direct no‐till seeding into standing stubble immediately after harvest of the previous crop, has permitted northward expansion of the North American winter wheat (Triticum aestivum L.) production area to include most of the western Canadian prairies. Twenty‐one broadcast ammonium nitrate fertilizer field trials were conducted in Saskatchewan from 1976 to 1986 to determine what influence timing of N fertilizer application had on grain yield, grain protein yield, and grain protein concentration of no‐till winter wheat. Time of N application had a significant influence on all three variables in approximately one‐third of the trials. Lower grain yield, grain protein yield, and grain protein concentration were attributed to loss of fallapplied N in four trials. In one trial, a prolonged period without rainfall left N temporarily stranded in a dry surface soil layer and lowered yield for early spring fertilizer application. Delays in spring N application also limited grain and grain protein yield‐N responses. However, dry spring conditions and late fertilizer applications did not limit grain protein yield to the same extent as it did grain yield. Therefore, increased grain protein concentration was often associated with delayed N availability. Reduced grain and grain protein yield, and increased grain protein concentration were observed for fall and early spring N applications in trials that experienced favorable spring growing conditions followed by a prolonged drought. Under these conditions maximum grain protein concentration ranged from 170 to 230 g kg−1, compared with approximately 150 g protein kg−1 dry grain under normal growing conditions.
Seasonal Variation in Chemical Composition of Forage Brassicas. II. Mineral Imbalances and Antiquality Constituents
Authors: Guillard K. , Allinson D. W. 
Published: July 2010

AbstractAlthough the nutritional value of Brassica crops is apparently high, antiquality constituents and elevated concentrations of certain minerals in herbage may negatively affect animal performance. This paper reports on seasonal variation of Ca/P, K/(Ca + Mg), and (K + Ca)/Mg ratios, and concentrations of thiocyanate (SCN−) and nitrate (NO−3‐N) in various Brassica crops. Turnip (B. rapa L.), rape (B. napus L.), swede (B. napus L.), and Tyfon [B. rapa L. × B. pekinensis (Lour.) Rupr.) were no‐till seeded in Connecticut on a Paxton fine sandy loam soil (coarse‐loamy, mixed, mesic Typic Dystrochrept) in summer and autumn of 1983 and 1984. Kale (B. oleracea L. var. acephala DC.) and the species listed above were seeded in the summer of 1987 and autumn of 1986 and 1987, to determlne NO−3‐N partitioning. Foliage Ca/P ratios were above 1:1 to 2:1, whereas root ratios were close to or slightly below this range. Ratios of Ca/P were significantly greater in summer than in autumn. The (K + Ca)/Mg ratio in 1983 exceeded the maximum desirable limit of 5.2 in autumn foliage and roots. Only turnip root ratios exceeded 5.2 in 1984. Concentrations of SCN− ranged from 160 to 840 mg kg−1 in foliage and from 274 to 845 mg kg−1 in roots. Foliage concentrations of NO−3‐N ranged from 21 to 1011 mg kg−1 in summer and from 2293 to 4750 mg kg−1 in autumn. Concentrations of NO−3‐N were lower in roots and showed the same seasonal pattern as foliage. Accumulation of NO−3‐N was highest in stems and petioles, lowest in leaf laminae, and intermediate in roots. Nitrate toxicity risk may be greater for ruminants grazed on autumn‐grown Brassica than those grazed on summer‐grown Brassica. Supplementation of P and iodine, controlled intake of Brassica crops, or addition of roughages should reduce concerns about mineral imbalances or antigrowth constituents associated with these forages.
Growth Response of Cultivars to Conservation Tillage in a Continuous Wheat Cropping System
Authors: Dao Thanh. H. , Nguyen H. T. 
Published: July 2010

AbstractChanges in tillage methods to cope with the continual erosion of our soil resource prompted the need to reassess current management practices for annual cropping systems of wheat (Triticum aestivum L.). A field study was conducted on Bethany silt loam (fine, mixed, thermic Pachic Paleustoll) from 1983 through 1987 near El Reno, OK to determine whether 10 hard red winter wheat cultivars respond differently to tillage systems. The cultivars were planted in moldboard‐plowed seedbeds, stubble‐mulch‐tilled seedbeds, or directly in standing stubble (no‐tillage). The effects of tillage method on plant stand, phenology, grain yield, and yield components were determined. Tillage method ✕ cultivar interactions varied with agronomic traits and years. In general, reducing tillage intensity delayed plant maturation beginning in the spring. Anthesis and leaf‐area duration periods occurred about 1 to 8 d later in mulch‐tilled and no‐tilled plots, compared with plowed plots. The prolonged vegetative phase indicated a potential benefit of no‐tillage in a wheat‐production system that includes a livestock grazing component during the winter months. Grain‐fill periods of no‐tillage wheat increased between 1 to 4 d in early‐maturity cultivars while those of later‐maturity cultivars were variable. The lack of tillage method ✕ cultivar interaction for grain yield indicated that development of wheat cultivars for emerging conservation technology may not be necessary. Notillage wheat yields were similar to conventional‐tillage yields, or slightly better in years with cold autumns that had erosive rains or dry springs. Early maturity cultivars consistently had stable yields during 1983 to 1987 with good resilience against environmental variations, but late‐maturity ones may not be suitable for no‐tillage winter wheat production. High temperature tolerance may be a potential breeding objective for plant types adapted to conservation tillage in the Southern Plains.
Plant Density and Defoliation Effects on the Recovery of Soybean Injured by Stem Cutoff During Vegetative Development
Authors: Hintz R. W. , Fehr W. R. 
Published: July 2010

AbstractThe current procedure for assessing the yield loss of soybean (Glycine max (L.) Merr.] caused by defoliation and stem cutoff does not take into account plant density. This study was conducted to determine the effects of plant density on the recovery of soybean injured by defoliation and stem cutoff during vegetative development. Plots were established during 2 yr at plant densities of 119 600, 191 300, 239 200, 310 900, and 382 700 plants ha−1. Treatments imposed on each of the five densities at stages V3 and V6 consisted of a factorial arrangement of 33 and 66% removal of the main stem with 0 and 100% defoliation. The stage of development at which treatments were imposed and the plant density of treated plots had no significant effect on percentage yield reduction. The results indicated that plant density is not an important factor when assessing yield loss of soybean from plant injury during vegetative development.
Predicting the Effect of Ammonium Placement on Nitrogen Uptake by Corn
Authors: Anghinoni L. , Barber S. A. 
Published: July 2010

AbstractA mechanistic model has successfully described the effect of P placement on P uptake by corn (Zea mays L.) and soybean (Glycine max L.). Model predictions for N have not been evaluated experimentally. The objective of this paper is to compare the effect of NH+4 placement on N uptake by corn found experimentally with that calculated with the mechanistic uptake model mentioned above. Observed N uptake values were obtained by growing corn in a growthchamber experiment using a sample of the 0 to 20 cm layer of Raub silt loam (fine‐silty, mixed, mesic Aquic Argiudolls) soil. Ammonium as (NH4)2SO4 was applied at a rate of 270 mg N per 3 kg soil to all or part of the soil in each pot. Fractional volumes fertilized were 1.00, 0.50, 0.20, 0.10, 0.05 and 0.02. Nitrapyrin [2‐chlorod‐6‐(trichloromethyl) pyridine] at 8 mg kg−1 was added to the soil to minimize nitrification of NH+4. Contribution to N uptake of each of the fertilized and nonfertilized fractions of soil were calculated with the mechanistic model from data for ion uptake kinetics, root distribution and morphology, and the soil parameters, soil solution NH+4 concentration, buffer power, and effective diffusion coefficient, used in the model. Predicted values were close to observed values when N fertilizer was mixed with all the soil. Calculated values became progressively smaller than observed values as the NH+4‐treated fraction of the soil decreased. When increases in the size of the NH+4‐treated soil volume due to NH+4 diffusion out of the initially treated volume and increases in the maximum N uptake rate per unit of root due to a reduction in the proportion of roots absorbing N were considered in the model, most predicted values approximated observed N uptake values.
Comparison of Three Herbicides For Selective Tall Fescue Control in Kentucky Bluegrass
Authors: Dernoeden Peter H. 
Published: July 2010

AbstractTall fescue (Festuca arundinacea Schreb.) can be an objectionable weed in Kentucky bluegrass (Poa pratensis L.). Field studies were conducted to determine safe and effective rates of chlorsulfuron [2‐chloro‐N‐{[(4‐methoxy‐6‐methyl‐l,3,5‐triazin‐2‐yl)amino]carbonyl}‐benzenesulfonamide], diclofop {(±)‐2‐[4‐(2,4‐dichlorophenoxy)phenoxy]propanoic acid), and metsulfuron [2‐([{[(4‐methoxy‐ 6‐methyl‐l,3,5‐triazin‐2‐yl}amino]carbonyl}amino]sulfonyl)benzoic acid] for selective tall fescue control in Kentucky bluegrass. Herbicides were field tested in either ‘Kenblue’ Kentucky bluegrass, grown on a Sassafrass sandy loam (fine‐loamy, siliceous, mesic Typic Hapludult), or an improved Kentucky bluegrass blend grown on a Chester silt loam (fine‐loamy, mixed mesic Typic Hapludult). Two applications of diclofo p reduced bluegrass cover and quality for extensive periods and generally provided inferior tall fescue control compared to chlorsulfuron or metsulfuron. Chlorsulfuron applied at 0.07 + 0.07 or 0.14 + 0.14 kg ha−1 did not reduce bluegrass cover at either site. Single applications of metsulfuron (0.07 or 0.14 kg ha−1) did not injure Kenblue; however, both rates injured the Kentucky bluegrass blend, and turf treated twice at the high rate required 1 yr for recovery. Single applications of chlorsulfuron (0.14 or 0.28 kg ha−1) or metsulfuron (0.07 or 0.14 kg ha−1) provided over 90% tall fescue control at the Kenblue site. Split applications of 0.07 + 0.07 or 0.14 + 0.14 kg ha−1 of either chlorsulfuron or metsulfuron provided over 90% control in the bluegrass blend. When compared to untreated turf, chlorsulfuron or split applications of metsulfuron applied in the fall, resulted in more bluegrass injury the following summer when turf was subjected to drought stress.
Spring Wheat Response to Enhanced Ammonium Supply: II. Tillering
Authors: Camberato J. J. , Bock B. R. 
Published: July 2010

AbstractSpring wheat (Triticum aestivum L.) grain dry matter (DM) is increased by increasing the proportion of fertilizer N as NH4 in the presence of a nitrification inhibitor (enhanced ammonium supply, EAS). This yield increase is manifest in increased heads plant−1. The objective of this study was to determine the effects of EAS on the number and origin of vegetative and headed tillers and on the number of fertile spikelets and kernels of each tiller. Knowledge of these effects will aid in determining when and how EAS increases grain DM. Increased grain DM with EAS in this study resulted from an increase in the number of headed tillers plant−1, which, for the most part, resulted from an increase in the number of vegetative tillers plant−1. Increases in vegetative tillers plant−1 were detectable within several days after the onset of tillering and were similar for a low‐tillering and a high‐tillering cultivar. The rate of mainstem development was not affected by EAS, but several tillers appeared earlier with EAS. For some tillers, EAS also increased the proportion of vegetative tillers forming heads. Increased grain DM was not proportional to increases in heads plant−1, because the additional headed tillers produced with EAS treatments were primarily T0 (coleoptilar mainstem) tillers and subtillers that had fewer spikelets head−1 and kernels head−1. The number of fertile spikelets head−1 of several tillers was increased by EAS treatments, but the number of kernels head−1 was increased for the T1 and T20 tillers, only. Negative effects of EAS treatments on late‐appearing tillers (T4, T5, and T22) were thought to result from increased self‐shading, increased plant wilting, and reduced soil‐N supply occurring at anthesis and resulting from the much greater plant DM prior to anthesis in EAS treatments. However, in general, increased spring wheat grain DM with EAS can be ascribed to the positive effects of EAS on tiller development.
Area Harvests Equivalency Ratio for Measuring Efficiency in Multiseason Intercropping
Authors: Balasubramanian V. , Sekayange L. 
Published: July 2010

AbstractBoth area and time factors have to be considered to quantify resource‐use efficiency in multiseason intercropping. The land equivalent ratio (LER), commonly used as an indicator of efficiency, is not suitable because it considers only the area factor to estimate intercrop advantages. The area time equivalency ratio (ATER) unrealistically assumes continuous crop growth throughout the year, thus it underestimates the advantages of intercrops. To avoid these problems, some authors used the mean value of LER + ATER as an arbitrary compromise. This paper proposes a new concept called area harvests equivalency ratio (AHER). This ratio incorporates the time factor in the form of number of possible harvests of each component crop in a system that could be obtained during the full intercrop period, if each component was monocropped. Four cases of intercrops were used to compare the above concepts. The AHER has proved to be a better efficiency indicator than others, except when a component species occupies the land for one season plus a fraction of the succeeding season (l.5, 2.5 seasons). In this particular case, other concepts are also disappointing. The problem with any attempt to quantify resource‐use efficiency is that there is no “true value” for yield advantages in intercrops. However, intuitively, AHER does seem to be nearer to the “true value” than others.