bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphorus Fertilization Reduces Vesicular‐Arbuscular Mycorrhizal Infection and Changes Nodule Occupancy of Field‐Grown Soybean1
Authors: Hicks P. M. , Loynachan T. E. 
Published: July 2010

AbstractMycorrhizal infection of the roots of soybean [Glycine max (L.) Merr.] has been reported to stimulate both nodulation and N2 fixation, especially in soils low in available P. Less is known about yield responses of field‐grown soybean due to mycorrhizal infection, and little is known about the effects of mycorrhizal development on nodule occupancy by Bradyrhizobium japonicum strains. These field studies used two soils each of 2 yr to evaluate the changes in mycorrhizal infection, nodule occupancy, total nodulation, and seed yield when the level of mycorrhizal infection was reduced by adding 112 kg P ha −1 as triple superphosphate. Soils were chosen to represent a range of Bray PI extractable P (12–91 kg P ha −1), and belonged to Aquic Hapludolls, Typic Argiudolls, and Typic Haplaquolls. Mycorrhizal infection and nodulation were assessed, and the occupying bradyrhizobial strains identified at growth stages R1.0 in 1984 and R4.5 in 1985. Even though P fertilization significantly reduced mycorrhizal infection from 25.4 to 5.2 vesicles per 4‐cm root length, there was no effect on the number of nodules per plant or on the resulting seed yields. There was a significant change, however, in nodule occupancy; serogroup 123 averaged 72% in the nonfertilized plots and 37% in the plots fertilized with P. Because mycorrhizal reduction and P fertilization were confounded in the field studies, a greenhouse study was conducted where vesicular‐arbuscular mycorrhizal infection could be controlled by soil sterilization. Inoculation of soybean by Glomus mosseae in sterile soil did not increase the competitiveness of USDA 123 when challenged by USDA 110.
Relationships between Canopy Botanical Composition and Diet Selection in Aeschynomene‐Limpograss Pastures1
Authors: Sollenberger L. E. , Moore J. E. , Quesenberry K. H. , Beede P. T. 
Published: July 2010

AbstractThe proportion of aeschynomene (Aeschynomene americana L.) in diets of cattle (Bos spp.) grazing aeschynomene‐limpograss [Hemarthria altissima (Poir.) Stapf et C.E. Hubb.] pastures is critical because protein concentration of the grass is often below levels thought needed to prevent intake depression (70 g kg−1 dry matter). A study was conducted on a Pomona sand (sandy, siliceous, hyperthermic Ultic Haplaquod) to determine the effect of botanical composition of aeschynomene‐limpograss canopies on the composition of diets selected by cattle. Esophageally fistulated steers were used to determine selection at first exposure to a pasture, and a sward difference technique was used to quantify the botanical composition of the herbage consumed during 48‐h mob grazing periods. Fistulated steers selected a diet higher in percentage aeschynomene than that in the upper layer of the canopy, but over a 48‐h grazing period, percentage legume in herbage consumed was not different than percentage legume in the grazed horizon. As the canopy was grazed down, total herbage bulk density of the surface layer increased and the legume leaf/stem ratio decreased. These factors ended selection for aeschynomene, and late in a grazing period animals were likely to choose the most accessible grass and weed forage and to avoid legume stems. These data are evidence of a dynamic plant‐animal interface in that (i) canopy characteristics influenced diet botanical composition, (ii) the act of consumption changed the canopy, and (iii) animals responded by altering their degree of selection. The results show that aeschynomene leaf and fine stem are highly palatable to cattle. This finding, along with previous reports of excellent forage quality, suggests that aeschynomene is capable of providing satisfactory levels of protein in steer diets if legume stands are adequate and if grazing ends before all aeschynomene leaf and fine stem are removed from the grazed horizon.
Vegetation and Animal Production from Reclaimed Mined Land Pastures
Authors: Hofmann L. , Ries R. E. 
Published: July 2010

AbstractLimited data are available on the productivity and persistence of reclaimed mined land in the northern Great Plains used for grazing. The purpose of this study was to compare standing crop, vegetation use, steer (Bos spp.) performance, soil compaction, and measurement methods on reclaimed cool‐season pasture near Center, ND, at three grazing intensities and grazed each spring over 5 yr. Light and moderate intensity pastures were grazed an average of 36 days, with an average total vegetation use of 35 and 47%, respectively. Heavy intensity pastures were grazed 27 days and averaged 93% use. Live vegetation production averaged 2040,2860,2390, and 1630 kg ha−1 dry matter in early July for ungrazed exclosures and light, moderate, and heavy intensities, respectively, over the 5 yr; litter averaged 1440, 1180,640, and 200 kg ha−1, respectively. Yearling steers gained an average of 64,86, and 31 kg ha−1 and 1.2, 1.0, and 0.3 kg day−1 at the light, moderate, and heavy intensities, respectively. The heavy intensity was detrimental to both vegetation and livestock production, but vegetation dry matter and liveweight gain improved when grazing was moderated in 1981. Grazing did not measurably affect soil bulk density in the top 150 mm of soil, but proving ring penetrometer measurements indicated increased soil compaction with increased grazing intensity. With 50% or less total vegetation removal in early summer, the reclaimed grassland provided sustained productive post‐mine grazing use with no signs of deterioration.
Irrigation and Plant Spacing Effects on Seed Production of Buffalo and Coyote Gourds
Authors: Nelson J. M. , Scheerens J. C. , McGriff T. L. , Gathman A. C. 
Published: July 2010

AbstractBuffalo gourd (Cucurbita foefidissima HBK) and coyote gourd (Cucurbita digitata Gray) are xerophytic perennial cucurbits with potential as oilseed or starch crops for arid and semiarid lands. This study investigated irrigation and plant spacing effects on growth, water requirements, and oilseed production of these species. Irrigation of first‐season buffalo gourds planted in 1981 at a 610‐m elevation site on Pima clay loam [fine‐silty, mixed (calcareous) thermic Typic Torrifluvent], and irrigation and plant spacing were evaluated on first‐season buffalo and coyote gourds at a 360‐m site in 1983 on Casa Grande sandy loam (fine‐loamy, mixed, hyperthermic Typic Natrargid) and Trix clay‐clay loam [fine‐loamy, mixed (calcareous), hyperthermic Typic Torrifluvent], respectively. Irrigation and plant spacing were evaluated on second‐season buffalo gourds planted in 1983. Irrigation did not affect first‐season buffalo gourd yields. Second‐season yields were reduced by irrigating when the available soil water was 75% depleted (I2) compared to irrigating when soil water was 50% depleted (I1). Coyote gourd yields were reduced by the I2 treatment in 1983 but not in 1984. Consumptive water use for first season buffalo gourds in the I1 treatment at the 610‐ and 360‐m sites was 870 and 645 mm, respectively. Consumptive water use was similar for coyote and buffalo gourds at the 360‐m site. In the first season, these species derived up to 50% of water used from the top 0.4 m of soil, and extracted water to a depth of at least 2.6 m. Irrigation did not affect water‐use efficiency (WUE) of either species. Buffalo gourds had higher WUE in the second season (0.09 kg seed m−3 water) than the first season (0.04 kg m−3). Plant spacings of 0.25 to 2 m in 1‐m spaced rows had no effect on first‐season yield in 1983, but in 1984 a quadratic relationship indicated that the closest and widest spacings reduced yields. Coyote gourd consistently outyielded buffalo gourd at the 360‐m site. Although these gourd species have promising water use characteristics for arid lands agriculture, the low seed yields of the cultivars currently available appear to limit their potential as oilseed crops.
Light Absorption and Competition in Mixed Sorghum‐Pigweed Communities
Authors: Graham P. L. , Steiner J. L. , Wiese A. F. 
Published: July 2010

AbstractPlant productivity in a community is governed in part by its ability to absorb and utilize photosynthetically active radiation (PAR). Studies on weed competition with a crop for light are limited. The effect of pigweed (Amaranthus hybridus L. and A. palmeri S. Wats) competition on leaf area development, light absorption, and dry matter production of fully developed grain sorghum [Sorghum bicolor (L.) Moench] was evaluated in a field experiment on Pullman clay loam (a fine, mixed, thermic Torrertic Paleustoll) at Bushland, TX, in 1984. Profile measurements (0–0.3, 0.3–0.6, 0.6–0.9, and >0.9 m above ground) of absorbed PAR (APAR) and leaf area index (LAI) by species were taken at four densities of pigweed (0, 1, 4, and 12 plants m−2). APAR calculated for sorghum in mixed communities of 1,4, and 12 pigweed plants m−2 was 79,77, and 49% of the APAR in weed‐free sorghum. Sorghum LAI was reduced to 81, 65, and 37% of the LAI of weed‐free sorghum in canopies with 1, 4, and 12 pigweed plants m−2. Sorghum LAI was concentrated in the 0.3‐ to 0.6‐m layer, while the taller pigweed plants had the greatest leaf area concentration above 0.6 m. By absorbing light in the upper canopy, pigweed reduced light penetrating into sorghum. Leaf measurements of photosynthesis and transpiration rates, leaf temperature, and stomatal resistance indicated a relatively minor degree of water stress under full canopy and high potential evaporation conditions; the level of water stress measured was not adequate to explain sorghum dry matter reduction in plots with 1, 4, and 12 pigweed plants m−2 to 78, 56, and 28% of that in weed‐free sorghum.
Herbicide Efficacy for Various Application Times in Doublecrop Wheat and Soybean
Authors: Higgins Jeffery M. , Whitwell Ted , Toler Joe E. 
Published: July 2010

AbstractEffective weed management is essential in reduced tillage doublecrop wheat (Triticum aestivum L.) and soybean [Glycine max Merr.] production. Field experiments were conducted on a Hartsells fine sandy loam soil (fine loamy, silaceous, thermic Typic Hapludalfs) near Crossville, AL, from 1981 to 1983 to determine the influence of application time on herbicidal efficacy of oryzalin [4‐(dipropylamino)‐3,5‐dinitrobenzenesulfonamide], pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine], and oryzalin + 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] for weed control. Herbicides were applied early preplant (EP) to fully tillered wheat, and preemergence (PRE) at soybean planting. Paraquat (1,1'‐dimethyl‐4,4'‐bipyridinium ion) was applied separately at 0.3 kg ha−1 at the time of PRE applications to ail plots that received other herbicide applications (EP or PRE) and alone as a check treatment. Early preplant treatments did not reduce wheat seed yields in 2 of 3 yr compared to the untreated control. Fall panicum (Panicum dichotomiflorum Michx.) and prickly sida (Sida spinosa L.) control were similar with EP and PRE applications of all herbicides. Fall panicum control ranged from 63 to 100%, and prickly sida control from 20 to 87%. Early preplant applications provided greater Pennsylvania smartweed (Polygonum pensylvanicum L.) control than PRE applications. Pennsylvania smartweed control was 5 to 70% greater with EP applications compared to PRE applications. Preemergence applications of oryzalin + 2,4‐D produced moderate (20%) soybean injury in 1982 and 1983. Soybean seed yields were similar with EP and PRE applications in 1981 and 1982; however, seed yields were from 26 to 103% greater with EP applications than PRE applications in 1983.
Performance of Orchardgrass, Smooth Bromegrass, and Ryegrass in Binary Mixtures with Alfalfa
Authors: Casler M. D. 
Published: July 2010

AbstractForage grass cultivars used in grass‐alfalfa (Medicago sativa L.) mixtures are generally the same as those used in pure stands. Little is known about the relative performance of grass cultivars in grass‐alfalfa mixtures in temperate North America. The objective of this study was to evaluate 78 cultivars and experimental populations of three species—orchardgrass (O), Dactylis glomerata L.; smooth bromegrass (SB), Bromus inermis Leyss.; and ryegrass (R), Lolium perenne L. and L. hybridum Hausskn.—for persistence and competitive ability in binary mixtures with alfalfa. Entries were seeded in 3‐m single‐row plots, spaced 0.9 m apart, in six randomized complete blocks at Arlington, WI, and overseeded with ‘Saranac’ alfalfa in April 1983. Plots were managed for 3 yr following the seeding year by taking three cuttings at late bud to early flower of alfalfa before 1 September. Species rankings for vigor and ground cover were O > SB > R; rankings for regrowth after cutting were O > R > SB. Orchardgrass increased in ground cover in each year, SB decreased in the first year and increased in subsequent years, while R decreased in the first year and remained nearly constant for the duration of the study. True ground cover ratings (TGC, expressed as a percentage of initial established stands) ranged from 46 to 508% for O, 31 to 233% for SB, and 21 to 81% for R. Cultivar variation for TGC was related to maturity in O, prior selection history in SB, and ploidy and species in R. Variation among entries was generally not related to performance in pure stands. The study provided an efficient procedure for developing preliminary evaluations of cultivars and experimental populations in mixture with alfalfa.
Simulating Growth and Yield Responses of Sorghum to Changes in Plant Density
Authors: Huda A. K. S. 
Published: July 2010

AbstractThough numerous field experiments have been conducted on the effects of plant density on growth and yield of sorghum [Sorghum bicolor (L.) Moench], tests showing the ability and validity of a sorghum simulation model to respond to changes in plant density have not been reported previously. Thus, a field experiment was conducted at ICRlSAT Center, Patancheru, India, in the 1983 rainy season on a Vertisol (fine, clayey, montmorillonitic, isohyperthermic Typic Pellustert) to test the validity of the sorghum simulation model, SORGF, for simulating the effect of plant density on growth and development of sorghum. Simulations were compared to data collected on phenology, leaf area indices (LAI), total dry matter (TDM), and grain yield for five plant densities (4, 8, 12, 16, and 20 plants m−2) of two sorghum cultivars (CSH 6 and SPV 351). Observed TDM and grain yield increased up to 16 plants m−2, while simulated TDM and grain yield increased up to 20 plants m−2. The model, on average, underestimated TDM by 8% and overestimated grain yield by 2%. Good agreement between observed and simulated LAI, TDM, and grain yield across five plant densities and two cultivars was supported by the insignificant differences of observed and simulated values from a one‐to‐one line. The model was further validated using climatic data from the ICRISAT Center between 1976 and 1984. Simulated grain yield using plant densities of 12 plants m−2 were within 3% in 6 yr and between 11 and 20% in the other 3 yr of observed data using plant densities of 13 plants m−2. Results from this study suggest that the SORGF model appears useful for simulating the effect of plant density on the growth and yield of well‐managed sorghum when input data on cultivar, climate, soil, and agronomic management are available.
Nutrient Norms for Cured Burley Tobacco
Authors: Evanylo G. K. , Sims J. L. , Grove J. H. 
Published: July 2010

AbstractTobacco (Nicotiana tabacum L.) cured leaf yield, price, and total alkaloid concentration can be altered through appropriate fertilization programs. A study was undertaken to establish critical values and Diagnosis and Recommendation Integrated System (DRIS) norms using total N, NO3–N, P, K, Ca, Mg, Mo, Mn, Na, Cl, and S for burley tobacco grown on Maury silt loam (Typic Paleudalf) and associated soils in Central Kentucky. Preliminary sets of critical nutrient level and DRIS norms were calculated for cured burley tobacco leaf using a data bank of 500 observations collected from 15 field studies conducted between 1972 and 1984. Differences in optimum nutrient levels and DRIS ratios existed between subpopulations created using a single dividing criterion for yield, price, or total alkaloid concentration. Narrower nutrient ranges were required for high‐yielding than for high‐priced, or for low total alkaloid‐containing leaf. Leaf total N concentration did not vary among high‐yielding, high‐priced, or low alkaloid‐containing tobacco. High K concentrations were more important in attaining high yield than high price. Low Cl and high S concentrations were associated with low total alkaloids. The proposed norms should serve as useful guides in burley tobacco research or production to optimize tobacco composition for quality and safety without concurrent loss in yield.
Management Effects on Kernel Breakage Susceptibility of Early Maturing Corn Hybrids
Authors: Moes J. , Vyn T. J. 
Published: July 2010

AbstractThe tendency of corn (Zea mays L.) kernels to break during post‐harvest handling causes problems for several user groups. Crop management factors have been reported to influence breakage susceptibility, but the effects of hybrid, plant density, harvest moisture content, and drying temperature on grain corn breakage susceptibility have not yet been investigated in a single study. To this end, a field experiment was established in May 1985, at the Arkell Research Station, Arkell, Ontario. Five commercial hybrids, Hyland HL2280, DeKalb XL11, Co‐op 2645, First Line 1636, and Pioneer 3949, were grown at 5.6 and 7.1 plants M2, harvested at 310 and 240 g kg−1 moisture content (wet basis) and dried at 30 and 80°C to approximately 150 g kg−1 moisture content. A Wisconsin Breakage Tester was used to measure breakage susceptibility. In the breakage tests, the main effects were statistically significant, as well as the interactions of hybrid with plant density, harvest moisture, and drying temperature, and of harvest moisture with drying temperature. Of these, only the interaction of hybrid with drying temperature resulted in differences large enough to be commercially significant. Four hybrids were relatively resistant to breakage when dried at 30°C; when dried at 80 °C, increases in breakage susceptibility were much larger for two hybrids than for the other three. Of the other parameters measured, the degree of multiple stress cracking and kernel length were most strongly related to breakage susceptibility, but levels of severe kernel damage and fine broken corn ( <4.76 mm), and kernel thickness were also related to breakage susceptibility. Test weight was not related to breakage susceptibility.
Effect of Added Urea and Potassium Chloride on Yields of Corn over Four Years and on Soil Potassium
Authors: MacKenzie A. F. , Phillip L. E. , Kirby P. C. 
Published: July 2010

AbstractSilage corn (Zea mays L.) is a major crop in eastern Canada, and yield increases due to added N and K have been noted. However, possible interaction between N and K, and the effect of weather conditions on yield response and maturity must be determined for rational use of N and K fertilizers. A fertilizer experiment on the production of silage corn using urea and KCI was established on an Ormstown silty clay loam (fine silty, mixed, non‐acid, mesic Typic Humaquept) for 4 yr. Rates of fertilizer were 0, 90, and 180 kg N ha−1, and 0, 60, and 120 kg K2O in the first 2 yr, increased to 0, 120, and 240 kg K2O ha−1 in the last 2 yr. Yields of silage corn were increased with N in 3 yr and with K in 2 of the 4 yr. An interaction between N and K was found in the years when there were yield responses to added KCl, indicating that increased crop yields with K occurred only at relatively high N rates. Added N increased dry matter contents of corn plants, whereas added K reduced dry matter contents at low rates of N. Relative yields of the control plots over the high N–K plots were correlated positively with precipitation during the growing season. Added urea when combined with added KCl increased exchangeable and soluble K, probably due to reduced K fixation by illite, mica and vermiculite minerals in the soil.
Use of Unsaturated Salt Solutions to Generate Leaf Tissue Water‐Release Curves
Authors: Livingston N. J. , de Jong E. 
Published: July 2010

AbstractOsmotic adjustment and changes in cell wall elastic modulus are important processes that enable plants to maintain physiological activity and prolong leaf survival as plant water deficits increase. This paper describes a simple and practical technique to produce tissue water‐release curves that allows many measurements of osmotic potential (π), elastic modulus (ε), and apoplastic water fraction (A) to be made both rapidly and routinely. Discs, 6 mm in diameter, were punched out of hydrated leaves of wheat (Triticum aestivum L.), barley (Hordeum distichon L.), and oil‐seed rape (Brassica napus and B. campestris) and weighed immediately on a precision balance. Each disc was then suspended above an unsaturated salt solution of known molality in a sealed test tube held at 5°C in a stirred water bath. Eighteen salt solutions were used whose water potentials ranged from −0.09 to −4.67 MPa. After 12 h the discs were reweighed and then oven dried at 65°C for 24 h. Water‐release curves were obtained by plotting paired values of disc relative water content and salt solution water potential. Using leaves from the same stem, π, at full and zero turgor, ε, and A determined from the water‐release curves were compared with pressure chamber measurements made on the next lower leaf. Measurements of wheat, barley, and oil‐seed rape π, ε, and A obtained from water release curves generated using salt solutions were within 0.2 MPa for π, 3.0 MPa for ε, and 0.07 for A, of those obtained using a pressure chamber over a wide range of π and ε. More than 40 water‐release curves could be generated over 2 d.
Subterranean Clover Reseeding
Authors: Evers G. W. , Smith G. R. , Beale P. E. 
Published: July 2010

AbstractHard seed production is critical for reseeding of winter annual clover (Trifolium, spp.) under southeastern U.S. climatic conditions. This study was conducted to determine the reseeding capability of a diverse set of subterranean clovers (Trifolium subterraneum L., T. yanninicum Katzn. and Morley, T. brachycalcinum Katzn. and Morley). Thirty‐three subterranean (sub) clover entries were grown in small, replicated plots in fall 1982 to spring 1983 at Angleton (Typic Pelludert) and Overton (Glossic Paleudalt), TX. Reseeding was monitored from June 1983 through December 1985 by counting and removing volunteer sub clover seedlings. Seedling density for all entries at both locations in the first reseeding year (June 1983‐May 1984) accounted for 69% or more of the total seedlings observed during the 2.3‐yr period. In the first reseeding year at Angleton, 15 entries germinated more seed from June to 15 September (summer) than from 15 September to January (fall). Seed survival at Angleton into the second reseeding year was less than 10% of total for all the cultivars evaluated except ‘Meteora’. In the first reseeding year at Overton, only the cultivar ‘Nangeela’ had a higher summer than fall germination. Seed survival at Overton into the second reseeding year was 21 and 29% for the cultivars ‘Esperance’ and ‘Clare’, compared to less than 1% for ‘Mt. Barker’. Summer seed germination was higher and second‐year seed survival less at Angleton compared to Overton. Sub clover reestablishment was adequate for most entries in the first reseeding year at both locations, but reseeding estimates were marginal to very low for most entries in the second and third years. Sub clover germplasm with improved reseeding potential was identified.