bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spacing Pattern and End‐Trimming on Solid‐Seeded Soybean Plot Comparisons
Authors: Philbrook B. D. , Oplinger E. S. 
Published: July 2010

AbstractPlanting soybean [Glycine max (L.) Merr.] in solid stands increases grain yields for many producers. Testing techniques that simplify plot work but separate the effects of adjacent plots in solid‐seeded soybean have not been described. This study was conducted to determine the influence of plot planting patterns and time of end‐trimming on soybean cultivar comparisons in a solid‐seeded system. The effects of three planting patterns and end‐trimming at two stages of growth on yield, yield components, and agronomic characteristics of six cultivars were investigated in field studies conducted near Arlington, WI, from 1982 through 1984. All patterns had seven 0.18‐m harvest rows plus a border row spaced 0.28 m from each of the outside harvest rows that created a tramline through the plot. Yields of cultivars were inflated 6% when the distance between border rows of adjacent plots was increased from 0.18 m in Pattern 1 to 0.48 m in Pattern 2; however, relative yield differences among cultivars were consistent. Adding an additional border row using a common cultivar (Pattern 3) increased the distance between harvest rows of adjacent plots without increasing the distance between their borders. Soybean planted using Pattern 3 performed more consistently with respect to lodging, plant height, and yield than when either of the other patterns was used. Plot yields were inflated an average of 10% when plot ends were not end‐trimmed late in the season near plant maturity, as opposed to early season end‐trimming only. Cultivars did not respond uniformly to end‐trimming in 1983. Final plant density, pods per plant, and seed weight averaged 55, 60, and 6% more in the plot ends than in the middles, while the number of seeds per pod was unchanged. Response of pods per plant to end effects was greater for ‘Hardin’ and ‘Corsoy 79’ in 1982, and ‘Hodgson 78’ in 1984 than for the other cultivars. Techniques for solid‐seeded soybean plot comparisons are improved by using additional border rows to separate plots and by end‐trimming at or near harvest maturity.
Grain Moisture Loss Rate of High‐Oil and Standard‐Oil Maize Hybrids
Authors: Mišević D. , Alexander D. E. , Dumanović J. , Kerečki B. , Ratković S. 
Published: July 2010

AbstractHigh‐oil hybrids having the same date of anthesis as normal‐oil hybrids are frequently found to have higher moisture content in the grain at harvest time. Field drying rate of maize (Zea mays L.) grain was followed in nine single‐cross hybrids differing in percent oil in the kernel and in agronomic traits. The objectives of this study were to determine the duration of the grain filling period (GFP), moisture content at physiological maturity, and grain moisture loss throughout the period after physiological maturity. Hybrids were grown in 1984 in a randomized complete‐block design with four replications at Urbana, IL, and Zemun Polje, Yugoslavia. Three ears were harvested from each plot 14 d after pollination (DAP) and at weekly intervals until 70 DAP. Percent moisture in the grain, and 100‐kernel weight were measured for each hybrid, harvest date, and location. High‐oil hybrids had higher moisture content 70 DAP than did normal‐oil hybrids. Differences in kernel moisture percent among oil groups at the beginning of GFP were not significant at Zemun Polje, but were significant at Urbana. At the time of approximate physiological maturity the 7% oil group had significantly lower moisture percent in the grain than did the normal‐ and 9% oil hybrids at both locations, and had significantly lower moisture percent in the grain than the 9% oil hybrids at Zemnn Polje only. There were no significant differences in rate of kernel water loss among oil groups throughout the GFP. However, normal‐oil hybrids were faster drying than 7 and 9% oil hybrids after physiological maturity. Differences in the drying down rate between the 7 and 9% oil groups were not significant at one (Urbana) of the two locations.
Nodule Occupancy by Introduced Bradyrhizobium japonicum in Iowa Soils
Authors: Berg R. K. , Loynachan T. E. , Zablotowicz R. M. , Lieberman M. T. 
Published: July 2010

AbstractCompetitive indigenous strains of Bradyrhizobium japonicum occupy many soils of the Midwest, but they are generally considered to be less efficient in fixing N2 than many strains added as inoculants. Inoculant strains will not improve N2 fixation in soybean [Glycine max (L.) Merr.], however, unless they are able to form nodules on the host plant. This research evaluated whether strains selected for competitiveness in the greenhouse could compete against indigenous bradyrhizobia in the field in forming nodules when added at rates used for commercial inoculants, and whether higher nodule occupancy resulted in improved plant growth. Plots were established in north‐central Iowa at seven sites on four representative soil series. Seven to 12 strains were introduced in two or three soils each year from 1983 to 1985 at approximately 5.8 log10 viable cells per centimeter of row as granular‐peat inoculants. Results showed that average strain recoveries ranged from 0 to 46%. Some introduced strains differed in their competitive ability among the sites tested. The most competitive strains were AN8, AN10, AN11, AN23, AN27, and AN30, which typically occupied at least 20% of the nodules at a given site. When considering all members of each serogroup tested, strains from serogroup 123 were the best competitors. Increased nodule occupancy by the introduced strains did not result in increased plant growth or yield. Nodulating and nonnodulating ‘Clark’ isolines and urea fertilizer treatments were used to evaluate contributions from N2 fixation and plant growth with added N fertilizer.
Histological and Physical Factors Affecting Digestibility of Forages
Authors: Akin D. E. 
Published: July 2010

AbstractFactors that limit forage quality are complex and interactive. Structural characteristics that limit forage breakdown are primarily highly lignified support tissues like sclerenchyma and xylem. However, the presence of chemical barriers (likely the low molecular weight phenolic compounds) within “living” cell walls, such as the parenchyma bundle sheath and epidermis, prevents fiber degradation in these tissues. The presence of high proportions of these tissues in leaves of warm‐season grasses plus growth in hotter climates, which tends to speed maturity, combine to limit breakdown of warm‐season grass leaves compared to cool‐season species. Legume leaflets in warm‐ and cool‐season species can be readily degraded due to a high proportion of mesophyll. However, leaflets of certain species or cultivars with high tannin concentrations are poorly degraded, with mesophyll and vascular bundles comprising the residue. Grass stems have a more rigid structure than leaves, with the non‐digestible epidermis, sclerenchyma ring, and vascular tissue occupying about 30% of the tissues in the cross sections. In addition, mature grass stems have a poorly degraded parenchyma that contributes to a rigid structure in the residue. Parenchyma in legume stems is totally degraded, leaving a residue of a hollow cylinder surrounded by a uniformly lignified ring. Possibly, variations between structures of mature grass and legume stems contribute to observed differences in forage quality for these forage types. Rumen bacteria and fungi both physically associate with the more recalcitrant forage tissues. Fungi are better able to colonize the lignocellulosic tissues and can partially degrade the most resistant xylem tissues. Research avenues for improving forage quality are: (i) to enhance the ability of anaerobic fungi to weaken lignocellulosic barriers, (ii) to reduce the amount of non‐degradable barriers, particularly in stems, by plant breeding, and (iii) to improve by plant breeding the rate and extent of slowly or partially degraded tissues in leaves.
Aluminum Effects on Growth and Macronutrient Uptake by Annual Ryegrass
Authors: Rengel Z. , Robinson D. L. 
Published: July 2010

AbstractAnnual ryegrass (Lolium multiflorum Lam.) is an important forage crop in the southeastern USA, often grown on acid soils with potentially high levels of soluble Al. Effects of Al on growth and nutrient relationships in ryegrass are poorly understood. In this study four ryegrass cultivars were grown in a growth chamber in nutrient solutions at 0, 37, 74, 148, 296, and 592 µmol L−1 Al. The pH was initially adjusted to 4.2 and subsequent changes were monitored daily. More Al‐tolerant cultivars induced higher nutrient solution pH than more sensitive cultivars. For more Al‐tolerant cultivars, these pH changes were positively correlated with root and shoot tolerance indexes and negatively correlated with percent inhibition of Ca, Mg, K, and Na uptake. Root (shoot) tolerance index was defined as dry weight (wt.) of roots (shoots) grown with Al/dry wt. of roots (shoots) grown without Al. Changes in nutrient solution pH were effects rather than causes of differential Al tolerance, but once induced, differences in pH intensified cultivar differences in Al tolerance. An Al concentration of 37 µmol L−1 in solution significantly increased root Al concentrations, but very little Al was translocated to shoots. Higher shoot Al concentrations were found more often in the less Al‐tolerant cultivars Wilo and Urbana than in the more tolerant cultivars Gulf and Marshall. Larger root and shoot tolerance indexes, and lower percentages of inhibition of total Ca and Mg uptake were observed more often for more Al‐tolerant cultivars Marshall and Gulf than for more sensitive cultivars Wilo and Urbana. The average net influx of Ca and Mg was decreased where Al was added. Total uptake of K (quantity factor) was decreased by Al, while net K influx (intensity factor) increased for plants grown in the nutrient solution containing up to 74 µmol L−1 Al. Short exposure to Al increased net influx and total Na uptake. Longer exposure to higher concentrations of Al (at least 74 µmol L−1) inhibited both total uptake and net influx of Na. The root tolerance index was positively correlated with net influx of Ca, Mg, K, and Na. Increasing the nutrient solution Al level to 148 µmol L−1 greatly increased K/(Ca+Mg) ratio of shoots, thus increasing the grass tetany potential of the ryegrass forage.
Soil Temperature and Moisture Stress Effects on Kernel Water Uptake and Germination of Winter Wheat
Authors: Lafond G. P. , Fowler D. B. 
Published: July 2010

AbstractDirect seeding into standing stubble from a previous crop (stubbling‐in) has allowed successful production of winter wheat (Triticum aestivum L.) on the northern edge of the North American Great Plains. Soil at seeding is usually very dry with this production system, and the producer is often left with the dilemma of either seeding at the optimum date into a dry seedbed or delaying seeding until after a rain. The objectives of this study were to determine the importance of soil temperature and moisture potential on kernel water uptake and germination, so that the minimum requirements for successful crop establishment could be identified. Controlled environment studies demonstrated that germination could occur at moisture contents as low as 512 g water kg−1 kernel dry weight. Therefore, differences in rate of water uptake observed for kernels placed in a Typic Haploboroll soil at −0.2, −1.0, and −1.5 MPa did not result in differences in speed of germination. Temperature differences in the 5 to 30°C range had a large influence on rate of kernel water uptake and speed of germination. As temperature increased, rate of water uptake increased and median germination time decreased from 6.9 d at 5°C to 0.9 d at 25 and 30°C. This study demonstrated that the effects of temperature on speed of germination are much larger than those of moisture, indicating that seeding of stubbled‐in winter wheat should proceed at the optimum date regardless of seedbed moisture conditions.
Efficiency of Type 2 Modified Augmented Designs in Soybean Variety Trials
Authors: Lin C. S. , Voldeng H. D. 
Published: July 2010

AbstractReplicated designs are not practical when large numbers of test lines with limited seed supplies must be evaluated. Therefore modified augmented design (Type 2) was used to assess yield and other agronomic variables in a large number of soybean [Glycine max. (L). Merr.) strains in Ottawa. Thirty‐three experiments, each involving 100 to 500 test lines, were studied to determine the relative efficiency (RE) of adjusted versus unadjusted observations. There were seven groups of experiments in which the same set of test lines were used, and these were further investigated to determine RE in replicated conditions. Thus, RE was defined in two different ways; for nonreplicated (single) experiments the RE was measured by the ratio of variances between the unadjusted and the adjusted values of the subplot controls, and for the replicated experiments the RE was measured by the ratio of the mean squares of the “Replication ✕ Test line” (based on a randomized block design) between the unadjusted and the adjusted values. Adjustment was made for fertility variation by using the row and the column effects of control plots (Method 1), and the regression coefficient of the test plots on the control (Method 3). The results show that, for yield, the average RE by Method 3 was 220% for the nonreplicated and 167% for the replicated experiments, and 160 and 147% for Method 1 for the corresponding experiments. The adjustment was most effective for yield and plant height, somewhat less effective for protein and oil, and not very effective for maturity and 100‐seed weight.
Quadratic Programming Method for Determining Optimum Nitrogen Rates for Winter Wheat During Tillering
Authors: Baethgen W. E. , Taylor D. B. , Alley M. M. 
Published: July 2010

AbstractThe objective of this study was to determine the recommended amount of N fertilizer to be applied to winter wheat (Triticum aestivum L.) at Zadoks growth stage (GS) 25 that would optimize the use of a model previously developed to predict N required at GS 30. Quadratic programming models were developed for six experimental sites in Virginia to maximize marginal profit with N fertilizer application. First, the models were solved to determine the amounts of N necessary at GS 25 and at GS 30 to produce maximum profit. Then, four N fertilizer rates at GS 25 (N25) (0, 30,60, and 100 kg N ha−1) were evaluated by replacing the N25 value with each of these four predetermined amounts, and to again determine maximum profit. The difference (D) between the yields with maximum attainable profit (Y) without replacing N25 and the yields in which N25 was replaced With 0,30,60, and 100 kg N ha−1 (YR) was then calculated (D = Y –YR). The best N25 recommendation was selected as the one that minimized the mean value and standard deviation of D. This method was used for three N fertilizer:wheat price ratios (2.0, 4.0, and 8.0). The results indicated that the best recommendations for N25 were 50 to 60 kg N ha−1 for N fertilizer:wheat price ratios of 2.0 and 4.0, and 40 to 50 kg N ha−1 for a price ratio of 8.0.
Rescue of Soybean Flowers Destined to Abscise
Authors: Weibold William J. 
Published: July 2010

AbstractMany soybean [Glycine max (L.) Merr.] flowers abscise and do not contribute to yield. The objectives of this research were to determine the effectiveness of a proximal pod removal treatment designed to rescue soybean flowers destined to abscise and to determine if the effectiveness of this treatment changes with time after anthesis. ‘Williams 82’ soybean was grown in the field during 1985 and 1986. Racemes were tagged at anthesis of the flower at Position 1 (positions numbered along rachis from proximal to distal ends). Proximal pods (Positions 1 and 2) were removed from one half of the tagged racemes at varying times after anthesis. In 1985, this action resulted in nine treatments (4,6,7,8, 11, 12, 13, 15, and 16 d between anthesis and proximal pod removal). In 1986, five treatments of 3, 5, 7, 9, and 11 d were used. Abscission percentages for the untreated racemes, averaged over the 2 yr, were 5, 12, 30, and 59% for Positions 1, 2, 3, and 4, respectively. Average abscission percentages (all day intervals and both years) for Position 3 were 30% with proximal pods present and 7% with proximal pods removed. For Position 4, average abscission percentages were 59% with proximal pods present and 9% with proximal pods removed. Average seed weights pod−1 (all day intervals and both years) for Position 3 were 0.377 g with proximal pods present and 0.527 g with proximal pods removed. For Position 4, the average seed weights pod−1 were 0.540 g with proximal pods present and 0.610 g with proximal pods removed. In 1986, proximal pod removal increased number of seeds pod−1. Effectiveness of the proximal pod removal treatment in reducing abscission probability and increasing total seed weight pod−1 was not related to length of time between anthesis and proximal pod removal. The fate of pods destined to abscise can be reversed up to at least 11 d after anthesis.
Movement of Rhizobia between Alfalfa Plants
Authors: Chamblee D. S. , Warren R. D. 
Published: July 2010

AbstractEvidence on the rapidity of movement of rhizobia in the soil is inconclusive. Successful inoculation of most of the legume plants in a field would result in subsequent inoculation of the remaining plants if substantial movement of legume bacteria occurred. The objective of this study was to determine the distance rhizobia move in the soil between inoculated and noninoculated alfalfa (Medicago sativa L.) plants during the seeding year. Three field experiments were conducted in North Carolina. Experiments 1 and 2 were established on a Norfolk sandy loam (fine‐loamy, siliceous thermic Typic Paleudult) and Exp. 3 on an Appling sandy loam (kaolinitic thermic Typic Hapludult). Alternating rows of inoculated and noninoculated alfalfa (subplots) were seeded at spacings of 15,30 and 60 cm (whole plots) in four replications. Periodic measurements of nodulation, color, height of top growth and N concentration of top growth and roots were made. Results indicated that the lateral movement of rhizobia in an 11‐month period was largely limited to a distance of 15 cm. There was evidence that substantial N was obtained by noninoculated alfalfa rows from adjacent inoculated (15‐cm spacing) rows by sloughing and/or excretion.
Management of Long‐Term Field Experiments
Authors: Frye W. W. , Thomas G. W. 
Published: July 2010

AbstractLong‐term field experiments play an essential role in understanding the complex interactions of plants, soils, pests, climate and management, and their effects on sustainable crop production. This paper outlines the management problems associated with long‐term field studies and highlights design characteristics and management techniques to ameliorate these problems. Management of new long‐term studies includes selecting a suitable site, designing the experiment to facilitate statistical analyses and future expansion, collecting data commensurate with the objectives of the experiment, and incorporating nondestructive changes in the experiment as technology and objectives change. All of the old long‐term experiments that we studied have experienced various changes during their existence. Technological advances in areas such as plant populations, varieties, and fertilizer sources must be incorporated into long‐term experiments to maintain interest and generate useful data. Incidental changes, such as soil erosion, soil and fertility creep between plots, development of soil acidity, build‐up of weeds, and weather effects, are an inevitable feature of long‐term experiments. These are often management problems that must be reckoned with, but they usually do not violate the long‐term integrity or invalidate the results of the experiment. Primary treatments, e.g., tillage method and cropping system, cannot be changed without jeopardizing the long‐term status of the experiment. If properly managed, long‐term experiments generate unique, interesting, and valuable information that provides not only a link to the past but also insights into agronomic practices for sustainable future crop production.
Vernalization and Phyllochron in Winter Wheat
Authors: Cao Weixing , Moss Dale N. 
Published: July 2010

AbstractPhyllochron (degree‐days/leaf) has been used to describe phasic leaf development in dynamic wheat (Triticum aestivum L.) crop development models. Vernalization controls the rate of crop development in winter wheat. The objective of this experiment was to determine whether vernalization affected the thermal time required for winter wheat to produce leaves. ‘Stephens’ winter wheat plants were grown in a controlled environment chamber and in outdoor pots, using both pre‐vernalized and non‐vernalized germinating seed. In the outdoor pots plants became vernalized naturally and vernalization before sowing had no effect on growth, development, or flowering. In the controlled environment, up to the time of flowering of the vernalized treatment, there were no differences in phyllochron or total leaf number per main stem between the plants seeded using pre‐vernalized and non‐vernalized germinating seed. The non‐vernalized plants continued to produce tillers until the experiment was terminated, however, while tillering ceased at stem elongation in the vernalized plants. These results support the use of a constant value for phyllochron in simulating leaf development in both vernalized and non‐vernalized seedling winter wheat plants. However, they also show the need to adequately model the effect of vernalization on development (i.e., the cessation of leaf production and tillering in conjunction with flowering) in order to simulate the development of the crop leaf canopy.
Nitrogen Balance and Biomass Production of Newly Established No‐Till Dryland Agroecosystems
Authors: Wood C. W. , Peterson G. A. , Westfall D. G. , Cole C. V. , Willis W. O. 
Published: July 2010

AbstractSoil‐crop management affects the soil‐N balance and, thus, has a direct bearing on soil productivity. This study determined the effects of cropping intensity (crops/time) under no‐till and grassland establishment on aboveground biomass production and the system‐N balance after 4 yr (1985–1989). The effects were examined across toposequences in the West Central Great Plains that had been tilled and frequently fallowed for >50 yr. Production systems included wheat (Triticum aestivum L.)‐fallow (WF), wheat‐corn (Zea mays L.) or sorghum (Sorghum vulgare L.)‐millet (Panicum miliaceum L.)‐fallow (WCMF), and perennial grass (CG). Intense agronomic systems (WCMF) had greater aboveground production, greater N uptake, and greater percent plant residue retention than WF. Continuous grass systems had less aboveground production and N uptake but greater percent plant residue retention than agronomic systems. Soil‐profile NO3–N was lower under WCMF systems than WF systems, but organic N showed the opposite trend implying that more intense systems are at less risk for NO3–N leaching, and have greater potential for replenishment of soil‐organic N via enhanced immobilization. Aboveground biomass production and plant residue production increased downslope, but slope position had little effect on plant‐N uptake, plant residue retention, or soil‐N dynamics. Imposing no‐till and perennial grassland systems created a N‐balance disequilibrium, but more time will be required to ascertain the trajectory of N loss or gain due to establishment of no‐till or grassland management on these soils.