bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fall Harvest Management of Alfalfa. I. Date of Fall Harvest aind Length of Growth Period Prior to Fall Harvest
Authors: Edmisten K. L. , Wolf D. D. , Lentner M 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) harvest schedules are often interrupted by various factors. Interruptions in ideal alfalfa harvest schedules can delay the final harvest to dates considered critical to winter survival. The objectives of this study were to determine if a critical period for fall harvest management actually exists at 80°25′ W Long., 37°ll′ N Lat., and 610‐m elevation in Virginia, and if length of the growth period prior to final fall harvest (GPPFH) influences plant persistence and succeeding spring yields. Final fall alfalfa harvest was made 10, 20, or 30 September or 10,20, or 30 October for 2 yr in two identical experiments. Alfalfa was managed to achieve a 30‐, 40‐, 50‐, or 60‐d GPPFH. The soil was a mixture of Landisburg silt loam (fine‐loamy, mixed, mesic Typic Fragiudult) and Greendale silt loam (fine‐loamy, siliceous, mesic Fluventic Dystrochrept). Total nonstructural carbohydrates (TNC) in taproots and population of surviving plants were determined in December (214–351 g kg−1) and March (141‐221 g kg−1). Succeeding spring yields in May ranged from 1.0 to 3.1 Mg ha−1 and were a measure of accumulated influence of management treatments. Harvests made at any time during the fall period did not cause stand density reduction. Length of GPPFH was more important than date of fall harvest in making management decisions for fall harvest. Succeeding spring yields and TNC levels were generally high for the 50‐d growth period, and fall harvest yield would offset any reductions in spring yield observed in this study. In addition, fall harvests made with a 50‐d GPPFH maintained quality and leafiness better than the 60‐d GPPFH. With the exception of the 30 October fall harvest date, a critical period was eliminated by increasing the GPPFH to 50 or more days. The 30 October fall harvest required a 60‐d GPPFH for maximum spring production.
Growth of Wheat and Barley Seedlings at Different Matric and Osmotic Potentials
Authors: Hao X. , de Jong E. 
Published: July 2010

AbstractSince saline and drought conditions often occur together, plant response to the combined stresses is of considerable interest. The effects of matric and osmotic potential on shoot and root growth of wheat (Triticum aestivum, cv. Neepawa) and barley (Hordeum vulgare, cv. Bonanza) were investigated in a growth chamber. An artificially salinized Dark Brown Chernozemic sandy loam soil (Typic Borolls) was used in the study. The plants were germinated in nonsaline soil, transplanted onto columns with different osmotic and matric potentials, and grown for up to 8 d. Osmotic potentials of −0.1 to −1.0 MPa and matric potentials of −0.01 to −2.5 MPa reduced shoot and root growth, but the effects of the matric and osmotic stress were not necessarily quantitatively equal. A marked interaction between the two potentials occurred at high stress levels. In the most saline treatments, root growth was greater in the dry than the wet treatments. It is suggested that the latter is due to increased salt accumulation around the roots caused by more rapid mass flow in the wettest soil.
Interactive Water and Nitrogen Effects on Senescence of Maize. I. Leaf Area Duration, Nitrogen Distribution, and Yield
Authors: Wolfe D. W. , Henderson D. W. , Hsiao T. C. , Alvino A. 
Published: July 2010

AbstractStress effects on leaf senescence are important for maize (Zea mays L.), since production of new photosynthetic area is genetically pre‐determined. Interactive effects of water and N deficits on water potential components, green leaf area (GLA) duration, and N and biomass allocation during grain filling were evaluated in a 2‐yr field study conducted on Yolo loam (fine‐silty, mixed, nonacid, thermic Typic Xerorthents) under four treatments: 180 kg N/ha applied at planting, with (NI) and without (ND) irrigation; and no N fertilizer, with (OI) and without (OD) irrigation. Leaves of low N plants had reduced capacity for solute accumulation, and both water and N deficits caused 0.1‐ to 0.5‐MPa reductions in midday leaf turgor. Total GLA was smallest in the OD treatment, but senescence during grain filling was greatest in the ND treatment because of a high transpiration demand and a high reproductive sink demand for N. Ear removal reduced the rate of post‐anthesis leaf N decline of all treatments, and plants in the ND treatment showed a significant reduction in leaf senescence rate when ears were prevented. Grain yield of the OD treatment was <50% of NI yield in both years; ND and OI treatments had intermediate reductions. Although the timing and intensity of stress differed between treatments and years, both water and N deficits reduced leaf longevity, and GLA duration from anthesis to harvest was linearly related (r2 = 0.92) to final grain dry weight.
Wheat Yield Analysis in Relation to Advancing Technology in the Midwest United States
Authors: Feyerherm A. M. , Kemp K. E. , Paulsen G. M. 
Published: July 2010

AbstractImproving grain yields requires knowledge of sources of gains in the past to point the way to future advances. Our objectives were to analyze technology‐related yield changes of winter wheat (Triticum aestivum L.) in the U.S. Great Plains (a seven‐state region) and the Cornbelt (a four‐state region) since 1954 and to attribute them to major sources of variation. Within each of the 11 states, total yield change due to technology, yield change due to genetic improvement, and yield change due to applied N, were independently estimated. Yield change due to other factors was obtained by subtracting genetic and applied N induced changes from the total. Results were aggregated to regional levels. Wheat yields advanced 30 kg ha−1 yr−1 in the Great Plains and 43 kg ha−1 yr−1 in the Cornbelt from 1954 through 1979. In the Great Plains, 43,22, and 35% of the total increase was attributed to genetic improvement, applied N, and other sources, respectively. Comparable figures for the Cornbelt were 74, 22, and 2%. When the analysis was extended to 1984 for Nebraska, Kansas, and Oklahoma, the rate of increase remained almost the same, but the distribution among genetics, N, and other sources changed from 45, 25, and 30% for 1954 through 1979, to 61, 27, and 13% for 1954 through 1984. We concluded that from 1954 through 1979, genetics and applied N accounted for almost all the yield gain in the Cornbelt, but other factors (irrigation, pesticides, improved tillage, etc.) contributed about one‐third of the gain in the Great Plains. Technology continued to raise yields at the same rate in the central Great Plains during the 1980s, but a larger share was due to genetic improvement than during 1954 through 1979.
Forage Lignins and Their Effects on Fiber Digestibility
Authors: Jung H. G. 
Published: July 2010

AbstractThe lignin fraction of forage cell walls is negatively associated with fiber digestion by ruminants. Lignins can be classified as core lignins, highly condensed polymeric matrices; and non‐core lignins, low molecular weight phenolic monomers. Core lignins are covalently linked to hemicellulose in forage cell walls, with at least some of these linkage being alkali‐labile in grasses. Among the non‐core lignins, p‐coumaric acid is primarily associated with the core lignin fraction of cell walls whereas ferulic acid is generally linked to the hemicellulose fraction. The majority of non‐core lignin moities are esterified to other cell wall components, but ether linkages also seem to exist. Legumes and grasses differ in lignin concentration and composition. Physiological maturity of forages influences lignin content. Genetics and environmental influences have been observed to alter both concentration and composition of forage lignins. Lignification seems to depress digestion of grass cell walls more strongly than in legumes. Composition of core lignin may influence fermentation of forages more than does simply concentration. Non‐core lignins also are negatively correlated with fiber fermentation, but this may just reflect the positive correlation between core and non‐core lignin concentrations. Covalent linkage of lignin to carbohydrate has been shown to be important in model cell wall systems for inhibiting fermentation. Much remains to be learned about lignin structure and the mechanisms by which lignins interfere with ruminal digestion of forages.
Phosphorus Nutritional Requirement of Maize Seedlings for Maximum Yield
Authors: Barry D. A. J. , Miller M. H. 
Published: July 2010

AbstractIn a maximum yield experiment in Ontario, Canada, response of maize (Zea mays L.) to greater than recommended P fertilizer applications seemed to result mainly from improved P nutrition of seedlings. A 2‐yr study was conducted to determine the effect of P nutrition during the seedling stage on final yield. An outdoor, hydroponic system was used to vary P nutrition during growth and provide adequate levels of all other nutrients and water. Plants receiving the greatest or an intermediate P concentration solution had P concentrations of 7.2 and 4.4 g kg−1, respectively, at the 6‐leaf stage, whereas plants receiving the least P concentration solution had a shoot P concentration of 2.8 g kg−1. Plants that received the intermediate or least P solutions until the 6‐leaf stage but then received the greatest P solution to maturity attained shoot P concentrations of at least 5.0 g kg−1 8 d after increasing the P solution concentration. Grain yield was greater on treatments receiving the greatest P solution from the beginning than from the 6‐leaf stage (8.2 vs. 7.2 t ha−1), mainly because of a greater kernel number. Kernel number was most sensitive to P nutrition during the period from planting to the 6‐leaf stage. A shoot P concentration of at least 5.0 g kg−1 at the 6‐leaf stage was required to obtain maximum yield.
Variability in Alfalfa for Growth and Mineral Uptake and Efficiency Ratios under Aluminum Stress
Authors: Baligar V. C. , Elgin J. H. , Foy C. D. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) is an important forage legume that is known to be sensitive to soil acidity. A nutrient solution experiment was conducted under controlled growth conditions to evaluate the effects of Al (0, 75, and 150 µmol L−1) on growth, nutrient uptake, and mineral nutrient efficiency ratios (ER = shoot dry weight produced per unit element in shoot) in 15 selected alfalfa cultivars and lines. Growth of shoots and roots differed with Al levels and cultivars/lines. At 75 µmol L−1 the mean reductions of shoot and root dry matter yield were 29 and 6% of the control, respectively. Shoot nutrient contents showed significant positive correlations with shoot and root weights, and negative correlations with Al level and shoot Al concentrations. The ER values were used to classify cultivars and lines into efficient and inefficient utilizers of absorbed nutrients. With the exception of the ER for Ca, negative correlations were observed between Al level and ER. The cultivars and lines used in this study showed intraspecific genetic diversity for dry matter yield and ER values for the elements when plants were grown with or without AL.
Time of Desiccation Effects on Plant Composition and Subsequent Nitrogen Release from Several Winter Annual Cover Crops
Authors: Wagger M. G. 
Published: July 2010

AbstractEfficient utilization of N contained in cover crop residues by the subsequent summer crop requires an understanding of temporal patterns of N release as related to specific management strategies. The objective of this research was to determine, under field conditions, changes in plant composition and subsequent patterns of N release resulting from two desiccation dates approximately 2 wk apart (early and late) for rye (Secale cereale L.), crimson clover (Trifolium incarnatum L.), and hairy vetch (Vicia villosa Roth) cover crops. Averaged over 2 yr the late desiccation treatment resulted in increases in cover crop dry matter of 39, 41, and 61% for rye, crimson clover, and hairy vetch, respectively. Corresponding increases in total N content of the respective cover crops were 14, 23, and 41%. Significant differences in cellulose, hemicellulose, and lignin contents were found among cover crop residues between desiccation times. Nitrogen release from decomposing cover crop residues was monitored using nylon mesh (53 µm) bags. In general, the order of N release was hairy vetch > crimson clover > rye. Cover crops desiccated early decomposed faster, however, the relative magnitude of these N release patterns differed sharply between years. The percentage of initial residue N remaining after 16 wk for the early desiccation date in 1984 was 53, 14, and 13% for rye, crimson clover, and hairy vetch, respectively, compared with corresponding values of 59, 42, and 35% in 1985, which was characterized by a relatively dry growing season. Estimates of N released from each cover crop indicated that the potentially larger available N pool resulting from a delay in desiccation was offset by the slower rate of N release, especially for rye and crimson clover.
Evaluation of the Green Manure Potential of Austrian Winter Peas in Northern Idaho
Authors: Mahler R. L. , Auld D. L. 
Published: July 2010

AbstractThe objective of this field study was to determine the effect of Austrian winter peas [Pisum sativum spp. arvense (L.) Poir] used as either a green manure (GMP) or seed pea (SP) crop on soil N levels, and yields of subsequent crops of winter wheat (Triticum aestivum L.) and spring barley (Hordeum vulgare L.). The Austrian winter pea‐winter wheat‐spring barley (GMP‐WW‐SB) rotation was compared with seed pea‐winter wheat‐spring barley (SP‐WW‐SB), spring barley‐winter wheat‐spring barley (SB‐WW‐SP), and summer fallow‐winter wheat‐spring barley (SF‐WW‐SB) cropping sequences at two sites similar in annual precipitation. After harvest of the initial rotational crop, plots were divided into four subplots and four rates of N were applied as a topdress application following planting of ‘Stephens’ winter wheat. Spring barley was planted the third year. Winter wheat yields, spring barley yields, and inorganic soil N were not significantly affected by rotation ✕ N fertilizer interactions. Winter wheat yield averages following GMP, SP, SF, and SB were 6.6, 6.4, 6.3, and 4.7 Mg ha−1, respectively. Average N feitilizer equivalent values of 94, 75, and 68 kg ha−1 were provided by GMP, SP, and SF, respectively, to the following winter wheat crop. Yield differences resulting from crop rotation or N fertilization rate were not observed in the third year of the cropping sequence. Austrian winter peas used as either a GMP or SP crop provided more inorganic N for the following winter wheat crop than SF or SB. From a 3‐yr total yield the SP‐WW‐SB was the most efficient cropping sequence, as cereal yields were comparable to the GMP‐WW‐SB and SF‐WW‐SB rotations; however, since SP was harvested three crops instead of two (other rotations) were produced.
Nitrogen Fertilizer Carriers and Their Placement for Minimum Till Corn Under Sprinkler Irrigation
Authors: Raun W. R. , Sander D. H. , Olson R. A. 
Published: July 2010

AbstractNitrogen fertilizer efficiency is influenced by source of N and how sources interact with different methods of application. This study was initiated to evaluate various N sources and placement methods for sprinkler irrigated corn (Zea mays L.) grown under minimum tillage on a Sharpsburg silty clay loam (fine, Montmorillonitic, mesic Typic Argiudoll) in 1983 to 1985. In general, no differences were found for the yield parameters measured in this study for any of the N methods or N source combinations at 180 kg N ha−1. At the 90 N kg ha−1 grain yields were equal when N was applied broadcast preplant (using urea‐ammonium nitrate, urea, or urea‐ureaphosphate as sources) and when anhydrous ammonia was applied (preplant and sidedressed at the eight‐leaf stage). Both the broadcast preplant and anhydrous ammonia treatments were found to maximize grain yield at the low N rate. Broadcast preplant and anhydrous ammonia treatments provided superior grain yields, fertilizer N uptake in the grain, fraction of N translocated to the grain, and values for harvest index compared with the banding methods employed (dribble surface and band to the side of the seed) at the low N rate. Marked differences were observed in N utilization efficiency as only the banding methods showed fertilizer response above 90 kg N ha−1 while having no advantages over the other methods at 180 kg ha−1. There were generally small differences among N sources although urea‐ureaphosphate did appear to maximize total dry matter yields versus sulfur‐coated urea, urea, and urea‐ammonium nitrate over the 3‐yr period. Measurements made for ear leaf N did not consistently show high positive correlation with grain yield, therefore limiting the use of such a variable for identifying season N deficiencies.
Reducing Iron Toxicity in Rice with Resistant Genotype and Ridge Planting
Authors: Winslow M. D. , Yamauchi M. , Alluri K. , Masajo T. M. 
Published: July 2010

AbstractIron toxicity reduces rice (Oryza sativa L.) grain yield in many poorly drained swamps in West Africa. Two methods for alleviating Fe toxicity were examined, (i) the use of a resistant genotype, and l(ii) planting on ridges to aerate the upper root zone. Grain yield responses to these factors were measured in field trials conducted .in an inland valley swamp in southeastern Nigeria over two seasons on a set of paddies ranging from nontoxic to severely toxic. Two genotypes were compared, ITA 212 (susceptible) and ITA 247 (resistant). The severity of Fe toxicity in each paddy was estimated by visually scoring symptoms on ITA 212. Yield decline with increasing toxicity score fit simple linear regressions for both genotypes, but slopes differed significantly. On nontoxic paddies, ITA 212 yielded 10% more than ITA 247, but ITA 247 yielded 10 to 250% more than ITA 212 as toxicity increased from moderate to severe. Ridge planting did not significantly affect grain yield in 1985, but increased it by 245% in 1986 on a severely toxic paddy. The large increase in 1986 was attributed to the use of higher ridges (120 mm above the water surface) than in 1985 (30 mm). In both years the response to ridging was significantly greater when the resistant genotype was used. Resistant genotype and ridging appear to be effective technologies for reducing yield losses on Fe toxic soils, especially when used in combination.
Yield‐Soil Water Relationships in Sorghum‐Soybean Cropping Systems with Different Fertilizer Regimes
Authors: Roder W. , Mason S. C. , Clegg M. D. , Kniep K. R. 
Published: July 2010

AbstractCrop rotation of soybean [Glycine max (L.) Merr.] with grain sorghum [Sorghum bicolor (L.) Moench], and application of N fertilizer or manure generally increases grain sorghum yield. Little is known about rotation and fertilization effects on soybean yield in the Great Plains. Grain yields were measured from 1981 to 1987 in a cropping experiment started in 1980 on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll). The cropping treatments included continuous soybean, continuous grain sorghum, and grain sorghum‐soybean rotation. Fertilizer treatments consisted of control, manure (15.8 Mg dry matter ha−1 yr−11) and N (45 kg ha−1 for soybean and 90 kg N ha−1 for sorghum). Volumetric soil water content was determined with a neutron probe in 1985, 1986, and 1987. Soil water content was unaffected by fertilizer treatment. Water content in the upper 30 cm was generally greatest with continuous grain sorghum and least with continuous soybean. Soil water depletion to 120 cm in September was 10 to 36 mm greater with soybean than with grain sorghum. Crop rotation increased soybean yield, but N application did not. Manure application reduced soybean yield in 1986, but had no effect in the other years. Rotation and fertilization increased sorghum grain yield. The soybean yield advantage from crop rotation decreased as 1 April to 31 May rainfall increased. Cropping‐system induced differences in soil water content early in the growing season may be partly responsible for higher soybean yield with crop rotation.
Calculating Air Leakage Rates in Controlled‐Environment Chambers Containing Plants
Authors: Acock B. , Acock M. C. 
Published: July 2010

AbstractAir leakage rates from semi‐closed plant growth chambers under elevated CO2 concentration ([CO2]) treatments must be known in order to calculate plant CO2 exchange (CE). It is usually assumed that air leakage rates cannot be measured with plants in the chambers, so air leakage rates are measured before and after each experiment, and assumed to remain constant or vary linearly over time. Variability in leakage rate will diminish the accuracy of calculating CE. A method for calculating air leakage rate at night in the presence of respiring plants was devised. Simultaneous equations for three situations were developed: (i) when respired CO2 = CO2 leaked from chamber; (ii) when [CO2] is maintained at a set level overnight by injection; and (iii) when respired CO2 > CO2 leaked from chamber. All equations were based on two principles: (i) at night, the change in mass of CO2 within the chamber results from a loss of CO2 by leakage and a gain by respiration; and (ii) leakage of CO2 from the chamber is proportional to the difference between chamber [CO2] and ambient [CO2]. Respiration rate is assumed constant during the measurement period. Results are reported for the situation when chamber [CO2] reaches an equilibrium overnight (respired CO2 = CO2 leaked). Air leakage rate was found to have a coefficient of variability as high as 26.2% over eight daily measurements. Errors in calculating CE depend on the magnitude of the leakage rate, its variability, [CO2], and photosynthetic activity. A leakage rate that varied by 10% from two air changes h−1 in the 800 μL L−1 [CO2] treatment chamber could have given a 5% error in calculating CE during a cloudless day and a 14% error during a day with complete cloud cover. Using these procedures, variability in leakage rate can be checked automatically each day, with plants in the chamber, and without monitoring any gas except CO2.
Fraction of Thermal Units as the Base for an Evapotranspiration Crop Coefficient Curve for Corn
Authors: Amos Brigid , Stone L. R. , Bark L. D. 
Published: July 2010

AbstractA need exists to determine if evapotranspiration (ET) crop coefficient curves, based on a fraction of thermal units concept, could be used across cultivars that require various thermal unit totals from emergence to physiological maturity. Our objective was to develop such a curve for corn (Zea mays L.) and then to test the ability of this curve to estimate ET of cultivars of various maturity lengths. A basal crop coefficient curve for corn was developed by using field data obtained from 1974 through 1982 near Manhattan, KS and during 1981 and 1982 near Tribune, KS. The method involved calculating the ratios of measured ET rates adjusted for surface evaporation to reference ET rates, adjusting these ratios for the amount of available soil water, and then performing regression of the adjusted ratios against fraction of thermal units. The developed basal crop coefficient curve (n = 48, RMSE = 0.11, and R2 = 0.88) was then used to estimate the ET rate of three corn cultivars grown near Manhattan, KS in 1983 and 1984. We then performed linear regression of estimated ET rates against measured ET rates (water balance technique) for each cultivar. All regression equations and coefficients were significant at P < 0.001. The hypotheses that intercept equals zero and slope equals 1 could not be rejected for any of the cultivars. The use of fraction of thermal units as the crop coefficient base scale allowed for a general and accurate use of the basal crop coefficient curve across corn cultivars requiring various thermal unit totals from emergence to physiological maturity.