bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of pH on Proteolysis in Ensiled Legume Forage1
Authors: McKersie B. D. 
Published: July 2010

AbstractThe hydrolysis of proteins is extensive in ensiled forages but the production practices which may influence the extent of proteolysis remain to be characterized. An in vitro assay system was developed to estimate the relative rates of proteolysis and was compared to a laboratory silo system as a means of estimating the relative extent of proteolysis in three forage legumes, alfalfa (Medicago sativa L. cv. Iroquois), red clover (Trifolium pratense L. cv. Arlington) and birdsfoot trefoil (Lotus corniculatus L. cv. Leo). Plants were harvested from field plots as first and second cuts at the same time and were in the early bud to 10% bloom stages, depending on species and sampling time. Leaf homogenates containing chloramphenicol as an antibiotic were used as in vitro systems to monitor changes in the level of free amino acids at pH values between 4.0 and 6.5 at incubation times up to 72 h. This method provided a more satisfactory estimate of the relative proteolysis in ensiled forage than previous attempts using azocasein as substrate. Proteolysis was more extensive in alfalfa than the other two species. The optimal pH of proteolysis was approximately 6.0 in alfalfa, but 6.5 or above in red clover and birdsfoot trefoil. Low pH inhibited proteolysis. In a second experiment, forage from the same field plots as the in vitro experiment was ensiled in laboratory silos with the addition of 1% Na2CO3, 1% formic acid, 0.7% HCl, 1% formaldehyde, or no treatment. After ensiling for 30 days, protein hydrolysis was consistently highest in the alfalfa silages. The acid additives reduced proteolysis in all species, but a significant (P≤0.01) additive ✕ species interaction was observed in the second cut. A close positive relationship between the initial pH of the forage at ensiling and proteolysis was established for each species. The amount of protein degraded to free amino acids during ensiling of these legumes appears to be dependent on the proteolytic activity in the leaves, the rate of pH decline during ensiling, and the interaction between these two factors.
Response of Sugarbeet in Europe and the USA to Cercospora beticola Infection1
Authors: Smith G. A. 
Published: July 2010

AbstractThe interaction among cultivars and pathogen races is of particular relevance since sugarbeet (Beta vulgaris L.) cultivars developed in one geographic area may or may not be resistant in other areas. The objective of this study was to investigate the presence of pathological variability among indigenous biotypes of Cercospora beticola under field conditions as measured by cultivar ✕ location (biotype) interaction. Twelve sugarbeet cultivars developed in four different and unrelated breeding programs were evaluated for response to C. beticola in Greece, Italy, Spain, and the USA. The cultivars representing a wide range of inherent resistance were evaluated under field epidemics for 3 years. Results indicated that resistance to C. beticola was stable over the four diverse geographic locations and the 3 years, in all probability in the presence of several different biotypes of the pathogen. If pathogenic races do exist, as has been reported, their presence may be of limited consequence to germplasm development programs.
Row Spacing, Plant Population, and Water Management Effects on Corn in the Atlantic Coastal Plain1
Authors: Karlen D. L. , Camp C. R. 
Published: July 2010

AbstractLack of water because of erratic rainfall frequently limits corn (Zea mays L.) production on Typic Paleudults in the Atlantic Coastal Plain. Traditionally, wide (96 cm) row spacing and low plant population have been used to prevent water stress, but recently landowners have begun to invest in irrigation systems. Changes in row spacing, plant population, or fertilization practices may be required to achieve maximum water‐and nutrient‐use efficiency with those systems. We evaluated plant population treatments averaging 7.0 and 10.1 plants m−2 in single and twin rows on a Norfolk (fineloamy, siliceous, thermic Typic Paleudult) loamy sand during 1980, 1981, and 1982. Three water management [nonirrigated, irrigated using tensiometers (TENS) to measure soil‐water potential for scheduling, and irrigated using a computer‐based water balance (CBWB) for scheduling], and two fertilization programs were also evaluated in a four‐factor split‐plot design. Water management and plant population interacted significantly. Planting in twin rows increased grain yield an average of 0.64 Mg ha−1 (10 bu/A), but planting more than 7.1 plants m−2 significantly increased grain yield only in 1980. Irrigation increased grain yield 150, 161, and 8% in 1980, 1981, and 1982, respectively, as a result of increased kernel weight and number of kernels per ear. Increasing total N, P, and K application beyond 200, 30, and 167 kg ha−1, respectively, did not significantly influence grain yield or yield components. Yield advantages of narrow rows can be obtained on Coastal Plain soils which require subsoiling by using a twin‐row planting configuration. Irrigation can be scheduled using either tensiometers (soil‐water potential) or a computerized water balance without significantly changing corn grain yield, nutrient accumulation, or yield components.
Phosphorus Relationships in Potato Plants1
Authors: Westermann D. T. , Kleinkopf G. E. 
Published: July 2010

AbstractMaximum potato (Solanum tuberosum L.) tuber yields occur when an active plant canopy is maintained until normal plant maturation. Plant nutrient concentrations and uptake rates play a major role in maintaining an active plant top. The objectives of this study were to relate the plant P concentrations to the P and dry matter balance between tuber and total plant growth needs. Growth analysis data, plant and leaf total P concentrations and content, and the petiole soluble P concentrations were obtained on a 10‐to 14‐day sampling interval from P fertilization treatments in replicated field studies. The P concentration of the plant tops was significantly related to the petiole soluble P concentration and the P concentration of the active leaves. Total plant P uptake and dry matter production rates were not adequate for the tuber growth rate when the total P concentrations of the tops and active leaves were less than 2.2 g P kg−1. Soluble P concentrations in the fourth petiole down from the growing tip were less than 1000 and 700 mg kg−1 when P uptake and dry matter production rates were not adequate for tuber growth, respectively. Final tuber yields increased from 30 to 70 Mg ha−1 as the number of growing days past tuber set increased from 10 to 60 days for which the P concentration of the tops was above 2.2 g P kg−1. The petiole soluble P concentration decreased during the growing season following a semi‐logarithmic relationship. This relationship enabled the prediction of the petiole soluble P concentration for the rest of the growing season and could be used to predict when to apply supplemental P fertilizer.
Corn Hybrids Response to Four Methods of Tillage1
Authors: Hallauer A. R. , Colvin T. S. 
Published: July 2010

AbstractConservation tillage methods are becoming more widely used in corn (Zea maysL.) production because of energy costs and soil losses due to wind and water erosion. Changes in tillage methods, however, create different environments for the germination, development, and maturation of the corn plant. The objective of our study was to determine if single‐cross corn hybrids responded differently to tillage methods. A 5‐yr continuous corn study was conducted that included 14 single‐cross hybrids and four tillage methods (fall‐plow, striptill, spring‐disk, and no‐till). The soil was a mesic Typic Hapludoll. There was no significant interaction of hybrids by tillage methods, but significant differences were detected among tillage methods for yield, stand, and grain moisture. Hybrids planted in fall‐plow or spring‐disk conditions had greater yields, better stands, and lower grain moisture than when planted in strip‐till and no‐till conditions. Hybrids performed similarly for the fall‐plow and spring‐disk treatments, but spring‐disk had significantly greater plant residue cover (54.5 vs. 7.8%). Our results suggested that it was not necessary to test hybrids for different tillage methods.
Response of Solid‐Seeded Soybeans to Flood Irrigation. I. Application Timing1
Authors: Griffin J. L. , Taylor R. W. , Habetz R. J. , Regan R. P. 
Published: July 2010

AbstractVariation in seasonal rainfall accumulation directly affects soybean [Glycine max(L.) Merr.] yields. In southwest Louisiana, where soybeans are primarily grown in rotation with rice (Oryza sativaL.), moisture shortages frequently occur due to the presence of a traffic‐induced hardpan 15 to 20 cm below the soil surface, which restricts root development. Field studies were conducted in southwest Louisiana on a Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf) soil during 1981–1983 to study response of solid‐seeded ‘Dare’ (Maturity Group V) and ‘Ransom’ (Maturity Group VII) soybeans to flood irrigation. Water was applied at R2 bloom (B), R5– R6 pod fill (PF), B + PF, and full season (FS) as needed based on tensiometer readings (60 to 65 cbar). A nonirrigated control was included for comparison. In 1981 rainfall was adequate prior to bloom, but deficient when plants entered the reproductive stage. In 1982 and 1983, rainfall was generally deficient prior to bloom but adequate during the reproductive stage. Yield responses to the irrigation treatments varied among years and were directly related to rainfall distribution. Averaged over years, Dare yields were 161 kg ha−1higher (P=0.05) than the control where water was applied at B + PF and Ransom yields were 168 and 323 kg ha−1higher (P=0.05) than the control where water was applied at B + PF and FS, respectively. Seed/pod for Ransom and 100‐seed weight for Ransom and Dare averaged over years were significantly higher than the control only where water was applied FS. Pods/plant, seed/plant, plant height at maturity, lower pod height, and plant density were not affected by the irrigation treatments. Results indicate that in years where moisture is limited prior to bloom, early application of water can be beneficial, provided it is applied as needed throughout the remainder of the growing season. In years where moisture is adequate in early season prior to bloom, water should be applied during the reproductive stage if water shortage occurs.
Dry Matter Accumulation and Seed Yield of Determinate and Indeterminate Soybeans1
Authors: Beaver J. S. , Cooper R. L. , Martin R. J 
Published: July 2010

AbstractSome determinate soybean [Glycine max(L.) Merr.] cultivars developed for the northern USA yield as well as the conventional indeterminate cultivars. The principal objective of this research was to compare morphological and physiological traits of the determinate cultivar ‘Elf’ with the indeterminate cultivar ‘Williams’ and a determinate isoline of the cultivar ‘Clark.’ Field experiments were conducted at Urbana, IL in 1976 on a Flanagan silt loam (fine, montmorillonitic, mesic Acquic Argiudoll) and at Wooster, OH in 1981on a Wooster silt loam (fine‐loamy, mixed, mesic Typic Fragiudolf). Plants from weekly samples taken from the 5th week after emergence until R7 were separated into leaflets, petioles, main stems, branches, pods from main stems, and pods from branches. Patterns of dry weight accumulation for the plant parts were estimated using regression techniques. Estimates of seed yield components were obtained from an adjacent set of experiments. The genotypes accumulated leaf, petiole, and total dry weight in a similar fashion. Williams accumulated more main stem dry weight than the determinate genotypes. However, the difference in main stem dry weight was partially compensated by a greater branch dry weight of the determinate genotypes. Although Williams produced more main stem nodes, the determinate genotypes set as many pods on the main stems as Williams. The determinate genotypes produced a greater number of pods and more seed weight from branches than Williams. In 1976, Elf accumulated reproductive dry weight at a greater rate than Williams or Clark (dt1). The apparent harvest index of Elf was greater than the other genotypes during both years. Seed yields did not differ in 1976, whereas the determinate genotypes yielded slightly less than Williams in 1981.
Response to Soil Temperature of Dinitrogen Fixation (Acetylene Reduction) Rates by Field‐Grown Soybeans1
Authors: Sinclair T. R. , Weisz P. R. 
Published: July 2010

AbstractTemperature has a major effect on the dinitrogen (N2) fixation rate of legume nodules. Experiments were performed under field conditions to assess the influence of soil temperature on acetylene reduction rates by soybean [Glycine max(L.) Merr.]. Data were collected in situ under low acetylene concentrations such that observations of a number of plants were made every 30 min throughout diurnal periods. Significant positive correlations existed between acetylene reduction rates and soil temperature at temperatures below 30 °C. A linear model and an exponential model fit the data equally well over the 10 to 12 °C ranges where data were obtained. Since it was determined that both the nodule gas conductance and maximum activity of the nodule changed in parallel, it was not possible to identify which of these terms was responding directly to the changes in soil temperature. Between 30 and 33 °C little change in acetylene reduction rates with soil temperature was observed. Above 34 °C declines in acetylene reduction rates were observed. The decline was usually to 70% of the values observed in the 30 to 33 °C soil temperature range. Little or no recovery was observed in acetylene reduction rates after this high‐temperature–induced decline, indicating that a more permanent alteration had occurred in the nodules.
Distribution of Small Grain Residue Produced by Combines1
Authors: Allmaras R. R. , Douglas C. L. , Rasmussen P. E. , Baarstad L. L. 
Published: July 2010

AbstractA uniform distribution of small grain residues is needed in conservation tillage systems, but measurements are needed to describe the degree of uniformity or nonuniformity actually produced by combines. A combination of hand‐cut bundles of wheat (Triticum aestivumL.) plus straw before a combine pass; straw plus chaff deposit on a canvas apron and hand‐cut bundles of the uncut stubble were used to measure the distribution of small grain residue produced by 12 test combines. Header width varied from 5.5 to 7.3 m, grain production from 4.8 to 7.1 Mg/ha, and straw (plus chaff) production from 9.0 to 11.4 Mg/ha. From 52 to 64% of the straw plus chaff was threshed. An uneven residue distribution ratio (URDR) of maximum total to minimum total residue varied from 1.4 to 5.1 depending on combine and residue distribution system. A dispersion index (DI), which ranges from 0 for an even distribution to approximately 0.5 for a severely uneven distribution, varied from 0.09 to 0.42. All test combines with a standard flail spreader gave DI > 0.23. Dispersion indexes ≤ 0.14 were produced by a retrofit chaff spreader on a cylinder‐type combine, a farm‐shop modified flail spreader system on a rotary‐type combine, and an experimental straw chopper on a rotary combine. Agronomic and machinery operation problems associated with chaff rows suggest an URDR < 1.5 is needed to successfully manage no‐till after small grain harvest. A DI < 0.1 can be attained without excessive costs to improve spreading devices.
Organic Matter Relationship to Soil Nutrient Status and Aluminum Toxicity in Alfalfa1
Authors: Kapland D. I. , Estes G. O. 
Published: July 2010

AbstractThe objective of this investigation was to evaluate in unaltered soils the relationship of organic matter (OM) to soil nutrient levels and aluminum (Al) toxicity to alfalfa. The Apand B21horizons from 12 agricultural soils were collected from throughout New Hampshire. The pH range of the soils was 4.91 to 6.60, exchangeable Al was 0.01 to 0.89 cmol (p+) kg−1, organic matter was 6.6 to 81.6 g/kg, and textures ranged from sandy to silt loams. Four kilograms of each soil were potted and seeded to alfalfa (Medicago sativaL.) in a greenhouse experiment. The level of soil OM was highly correlated with top dry weights of 3‐week old alfalfa and top and root dry weights of 9‐week old alfalfa. Increases in OM levels also resulted in corresponding increases in exchangeable soil calcium, magnesium, potassium, extractable phosphorus (Bray 1), total nitrogen, and cation exchange capacity (CEC). A significant amount of variation in the top dry weights of 3‐week old plants and in the top and root dryweights of 9‐week old plants was accounted for by taking into consideration the interaction of Al and organic matter. With the use of three‐dimensional computer plotting programs, the critical Al level of alfalfa was correlated with soil OM levels (r=0.883). An incremental increase of 1% in soil OM on a dry‐weight basis (starting from about zero) increased critical Al levels by 0.3 cmol (p+) kg−1
Dry Matter Partitioning as Influenced by Competition Between Soybean Isolines1
Authors: Wilcox J. R. 
Published: July 2010

AbstractIntergenotypic competition has been shown to bias estimates of seed yield among soybean [Glycine max(L.) Merr.] genotypes. It is unknown how early in plant development intergenotypic competitive effects occur and what plant parts are affected. The objectives of this research were to determine what plant characteristics were affected by intergenotypic competition and how early in plant development these effects could be detected. Two soybean isolines ‘Clark’ and ‘Clark‐e2’, which matures 14 days earlier than Clark, were grown in hill plots at two spacings, 0.38 and 0.76 m between hills in 1981 and 1982. Plots were grown at Lafayette, IN on a Chalmers soil (finesilty, mixed, mesic Typic Haplaquoll). Three areas of hills were planted, (i) all hills of Clark, (ii) all hills of Clark‐e2, and (iii) alternate hills of Clark and Clark‐e2. At the fourth trifoliolate stage and at 2‐week intervals thereafter, three adjacent hills of Clark, of Clark‐e2, and three hills of each isoline in the area planted to alternate hills were harvested. Dry weight of stems, leaves, and pods plus seeds were recorded. Results were similar for the two spacings. Stem weight of Clark was significantly greater when bordered by Clark‐e2than when self‐bordered from the time of initial seed development through maturity. Stem weight of Clark‐e2was unaffected by the phenotype of surrounding plants. Leaf weight of Clark was significantly greater when bordered by Clark‐e2than when self‐bordered from the time of initial seed development until leaves began to yellow and drop. Like stem weight, leaf weight of Clark‐e2was unaffected by the phenotype of the surrounding hills. Competitive effects for pod weight (including seeds) were apparent throughout pod and seed development to maturity. Pod weight of Clark was enhanced and of Clark‐e2was depressed when the two genotypes were grown in alternate hills.
A Weighing Lysimeter for Evapotranspiration and Root Measurements1
Authors: Dugas William A. , Upchurch Dan R. , Ritchie Joe T. 
Published: July 2010

AbstractCrop water use is intimately tied to soil water and rooting patterns. Therefore, a lysimeter was fabricated which is unique in that root density and water content measurements can be made throughout an undisturbed soil profile coincident with whole‐profile evapotranspiration measurements. With this lysimeter, interrelationships throughout this soil profile between rooting depth and density, soil water content, plant water uptake, and evaporative demand can be evaluated. The lysimeter was constructed with a steel outer and inner box. The inner box contained an undisturbed soil monolith and was set on a scale, which in turn was set on the outer box floor. The 2.0 by 1.5 by 2.54 m monolith was obtained by forcing a steel box over a soil pedestal. Root growth and density and soil water are capable of being monitored throughout the monolith by using 36 clear, extruded acrylic tubes that were inserted horizontally through the monolith at various depths. Most of the soil mass is counterbalanced and the system is capable of resolving water mass changes equivalent to 0.02 mm. Evapotranspiration rates determined from the lysimeter compare favorably with empirical estimates. Costs for the facility and manpower requirements for operations and maintenance are substantial. However, root and soil water measurements, which are possible with this lysimeter, in conjunction with total‐profile water loss measurements, provide a means for quantitatively evaluating interrelationships throughout the profile between these important phenomena.
Pre‐Anthesis Defoliation Effects on Six Corn Inbreds1
Authors: Vasilas B. L. , Seif R. D. 
Published: July 2010

AbstractYield loss due to defoliation prediction charts have been developed for corn (Zea maysL.) hybrids, but not for inbreds. The latter is needed by the hail‐loss insurance industry. Field experiments were conducted at the University of Illinois on a Drummer silty clay loam (Typic Haplaquoll) in 1982 and a Flanagan silt loam (Aquic Argiudoll) in 1983 to evaluate the response of six corn (Zea mays L.) inbreds to 0, 50, and 100% defoliation at the 14‐leaf stage with respect to grain yields and yield components. One inbred, FRMo17rhm, produced yield responses quite different from the other five. Complete and 50% defoliation reduced grain yields of five inbreds by an average of 45.5 and 2.5%, respectively; and FRMol7rhmby 86.0 and 17.0%, respectively. With the exception of FRMo17rhm, yield, decreases were due more to a reduction in kernel number than kernel size. Yield reductions with 50% defoliation were due to a reduction in ear number as opposed to kernels per ear; whereas complete defoliation affected both yield components. Ear number was reduced both by decreasing the number of plants with double ears and increasing the number of barren plants. In general, genotypic differences in the yield response to complete defoliation coincide with genotypic differences in final leaf number and the effect of defoliation on increasing the interval between anthesis and silking.