bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fertilizer Requirements for New Plantings of Tall Fescue and White Clover on Two Low‐Fertility Ultisols1
Authors: Burmester C. H. , Adams Fred 
Published: July 2010

AbstractThe use of optimum fertilizer rates is an essential component of managing pasture forages. Tall fescue (Festuca arundinacea Schreb.), the dominant cool‐season pasture grass in much of the South, is often interplanted with white clover (Trifolium repen L.) for improved forage quality and as an N source for the grass. Inadequate P and K fertilizers allow weeds to invade new plantings; too much N fertilizer allows tall fescue to choke‐out white clover. Since a paucity of data exists on N‐P‐K requirements for new plantings of fescue and fescue‐clover, two on‐farm experiments were established on soils that are typical of extensive pasture acreage. Three N rates (0, 67, and 134 kg ha−1), four P rates (0,15, 30, and 60 kg ha−1), and four K rates (0, 28, 56, and 112 kg ha−1) were applied to fescue and a fescue‐clover mixture; tall fescue alone received an additional N rate of 201 kg ha−1. Swards were clipped when 20 to 25 cm tall. Optimum N rate for tall fescue differed for the two sites; with clover in the sward, however, it was zero for both. Soil test P was very low for both soils (2 mg kg−1), and the optimum P rate for fescue was 15 kg ha−1 on one soil and 45 kg ha−1 on the other. With clover in the sward, optimum P rates were 50 to 55 kg ha−1 on both soils. Soil‐test K differed for each site (low vs. medium), but optimum K rate for fescue alone was 28 kg ha−1 for each soil; with clover in the sward, however, optimum K rate was higher on the soil with the lower soil K (110 vs. 28 kg ha−1). In fescue‐clover swards, weeds became dominant in the no‐P and no‐K plots at one site; tall fescue became dominant at the other. White clover almost disappeared in the no‐P and the highest‐N plots at both sites.
Root Observations Using A Video Recording System In Mini‐Rhizotrons1
Authors: Upchurch D. R. , Ritchie J. T. 
Published: July 2010

AbstractTo understand the development of a crop, information is needed concerning the dynamics of root growth and water uptake. An extendible, 13 mm diam borescope, a low light, monochrome video camera, and a video tape recorder were combined into a system for in situ root observation through 51 mm inside diam clear acrylic tubes installed at an angle 30° from vertical. The viewing area was illuminated by two fiber optic light guides and a variable intensity light source. The observation tubes could also be used as access for a neutron probe to measure water uptake and root growth at the same point. Sector intersections rather than line intersections were counted and used to convert observations from the mini‐rhizotrons to root length densities. A comparison of root length densities determined through mini‐rhizotrons, installed in four orientations with respect to plant rows, with those determined by soil sampling indicates there was a linear relationship between the two techniques. When only depths greater than 20 cm were used the correlation was higher than when all depths were included. Results indicated that no installation orientation was clearly the best when only the depths greater than 20 cm were included. Because of the variability of the results from individual mini‐rhizotrons the results from several tubes had to be averaged before there was a satisfactory correlation with the bulk soil root length density.
Quantification of Aspergillus flavus Growth on Inoculated Excised Kernels of Corn Genotypes1
Authors: Adams Nancy J. , Scott Gene E. , King Stanley B. 
Published: July 2010

abstractCorn (Zea mays L.) genotypes that resist invasion by Aspergillus flavusor inhibit toxin production would be one major approach to controlling aflatoxin contamination. The primary objective of this study was to determine if a particular laboratory technique could be used to detect differences in responses to A. flavusgrowth among maize genotypes. In addition, several other aspects were considered including a) effect of pollen source, b) kernel sample size, c) incubation period, d) surface sterilization of kernels, and e) stage of kernel development when sampled. Evaluation of corn genotypes involved the removal of kernels from ears of field‐grown hybrids at various times throughout the kernel development period. Kernels were placed on NaCl amended agar in petri dishes and inoculated with a suspension of A. flavusconidia. After incubation, samples were evaluated by recording the extent of A. flavusgrowth on each kernel. Significant genotypic differences were detected at all stages of kernel development sampled. However, these differences were not always consistent over sampling dates nor were they always consistent over years for a given sample date. Visual ratings of kernels sampled early in the kernel development period were higher than the ratings of those kernels sampled toward the end of the maturation process. Surface sterilized kernels promoted more A. flavusgrowth than did unsterilized kernels. Evaluation of F1, seed produced on inbreds revealed significant differences between reciprocal crosses. When a resistant inbred was used as the female parent, the seed gave a resistant response. However, when the susceptible parent was used as a female, A. flavusgrowth on inoculated kernels was markedly greater.
Water Condensation on Peltier‐Cooled Thermocouple Psychrometers: A Photographic Study1
Authors: Wiebe Herman H. 
Published: July 2010

AbstractWater condensation on Peltier‐cooled thermocouple psychrometers (used to measure water potential) was observed and photographed under a microscope. Hundreds of minute droplets condensed on the entire junction within a second. As Peltier cooling continued these grew and coalesced, and after 1 min some 50 to 20 droplets uniformly covered the junction. After 5 min these had grown and merged into one (sometimes 2) large drop(s) that adhered to only part of the junction and to a lead wire. This drop grew by coalescence of the droplets that continued to condense on the junction until the drop eventually attained a constant diameter of about 0.3 mm, 6 times that of the junction. Evaporation during the psychrometric water potential measurement stage appeared uniform from the entire junction surface after short condensation times when it was covered with many small droplets. The two‐step procedure used to measure very low water potentials requires a large amount of condensed water. Poor psychrometric cooling is a hazard, however, if a drop only partly covers the junction after prolonged condensation times.
Physiological Responses to Sorghum Hybrids and Parental Lines to Soil Moisture Stress1
Authors: Hofmann W. C. , O'Neill M. K. , Dobrenz A. K. 
Published: July 2010

AbstractThe development of more drought‐resistant sorghum [Sorghum bicolor(L.) Moench.] germplasm depends on a fuller understanding of physiological responses to soil moisture stress. To investigate adaptation to moisture stress, physiological responses of six sorghum hybrids and their respective parental lines were evaluated under two irrigation treatments at Tucson, Ariz., in 1980 and 1981. The soil was a Comoro sandy‐loam (coarse‐loamy, mixed calcarious, thermic, Typic, Torrifluvent). Apparent photosynthesis, transpiration, diffusive resistance, and temperature differential (ambient temperature minus leaf temperature) were measured under field conditions at weekly intervals. Regression analysis was used to compare the physiological performance of the germplasm over a wide range of environmental conditions. Hybrid 4 was superior to its parental lines for all four physiological characteristics. In 1980, this hybrid was superior to the other hybrids in temperature differential (1.03°C) and transpiration (23.4 μg cm−2s−1) and had the highest mean apparent photosynthetic rates (45.9 mg dm−2h−1) and lowest mean diffusive resistance (1.41 cm s−1). Regression analysis is an effective tool that can be used for analyzing the physiological responses across diverse environmental conditions. By regressing the response of individual germplasm against the mean response of the population across all environmental conditions, the slope, mean, and coefficient of correlation were used to evaluate genotype‐environment interactions.
Use of Nitrogen Stress to Demonstrate the Effect of Yield Limiting Factors on the Yield Response of Soybean to Narrow Row Systems1
Authors: Cooper R. L. , Jeffers D. L. 
Published: July 2010

AbstractMost research indicates yields of soybean [Glycine max(L.) Merr.] are increased as row width is narrowed and in general indicates that the optimum seeding rate per hectare increases. In spite of good management (appropriate seeding rates and good weed control), the anticipated yield increase from narrow rows is not always observed. It was postulated that this may be due to the effect of some other yield limiting factor or factors in the environment. In this study, N stress was used as a model to test this hypothesis. Three experiments were conducted to evaluate the effect of N stress on the yield advantage of a 17‐cm row system over a 75‐cm row system. In two of the experiments, a genetic non‐nodulated cultivar (‘Clark rj1,’) was compared with normal cultivars (‘Corsoy’ and ‘Williams’) in 17‐ and 75‐cm row widths across four rates (0, 55,110, and 220 kg ha−1) of added N. In the third study, a normal cultivar (‘Beeson’) was grown in similar narrow and wide row systems on soil (fine‐loamy, mixed, mesic Agric Fradgiudalf) with a low level of Rhizobium japonicum(Kirchner) Buchanan and four rates (0,8.8,17.6, and 26.4 kg ha−1) of granular R. japonicuminoculant were used. Results from all three studies dramatically demonstrated that the potential yield advantage (15 to 25%) of the 17‐cm row system over the 75‐cm row system was minimized or eliminated under N stress situations. These results corroborate other research results that indicate late season moisture stress has a similar effect and strongly supports the hypothesis that any yield limiting factor, such as lodging, moisture stress, N stress, or other nutrient stress can significantly reduce the yield response of soybean to a narrow row system. This relationship may help explain previously published data which appears to be contradictory, as well as some of the variability in yield response to narrow rows reported by soybean growers.
Influence of Selected White‐Rot Fungi and Topdressings on the Composition of Thatch Components of Four Turfgrasses1
Authors: Sartain J. B. , Volk B. G. 
Published: July 2010

AbstractIn a pot‐culture experiment with four highly‐thatched turfgrasses [bermudagrass, Cynodon dactylon(L.) Pers.; centipedegrass, Eremochloa ophiuroides; Kentucky bluegrass, Poa pratensisL.; and St. Augustinegrass, Stenotaphrum secundatum(Walt.) Kuntze] we examined the influence of selected white‐rot fungi and topdressings on the degradation of thatch components. Cores of each turfgrass were placed in pots and inoculated with one of four species of white‐rot fungi (Polyporous giganteus, Coriolus versicolor, Phebia gigantea, or Phanerochaete chrysosporium). Pots were reinoculated with the appropriate fungus 14 days after the initial inoculation and after the 6 month sampling. Subplot treatments of the split‐plot design were three topdressings (none, 0.31 cm sand, and 0.31 cm sand containing 4% colloidal phosphate). Samples of thatch were collected 6 and 12 months after inoculation and analyzed for cellulose and lignin by the acid detergent fiber procedure. Total oxidizable organic material and C and N were also determined. The cellulose content of bermudagrass and centipedegrass thatch was significantly reduced by Phebia gigantea, but no fungus significantly reduced the thatch cellulose content of St. Augustinegrass and Kentucky bluegrass. Coriolus versicolorsignificantly reduced the lignin content of thatch from all turfgrass species and the total oxidizable organic material of bermudagrass and centipedegrass. It appears to hold some potential for decomposing accumulated thatch. Topdressings with sand or a mixture of sand and colloidal phosphate significantly reduced the cellulose and lignin contents of thatch from most of the turfgrass species. Adding colloidal phosphate to the sand did not significantly increase the decomposition rate of the thatch. Kentucky bluegrass thatch contained the lowest quantity of lignin, and St. Augustinegrass thatch the least cellulose.
Row Pattern and Seeding Rate Effects on Value of Virginia‐Type Peanut1
Authors: Mozingo R. W. , Coffelt T. A. 
Published: July 2010

AbstractThe improvement of peanut (Arachis hypogaeaL.) productivity by genetics or management systems is a continuing process. The effects of cultivars, row patterns, and seeding rates on market value of virginia‐ type peanut were studied in a 2 ✕ 2 ✕ 2 factorial experiment for 4 years at the Tidewater Research and Continuing Education Center in Suffolk, Va. ‘Florigiant’ and ‘Virginia 81 Bunch’ (VA 81B) cultivars were seeded at the rate of 143 516 and 215 274 seed ha−1in single and double row patterns. Soil types were coarse‐loamy or fine‐loamy, silicious, thermic Aquic Hapludults (Nansemond fine sandy loam, 1977 and 1980, Nansemond loamy fine sand, 1979, and Eunola loamy fine sand, 1978). VA 81B had a higher percentage of extra large kernels, sound mature kernels, total meat, and market value ha−1than Florigiant. Florigiant produced a higher percentage of fancy size pods; however, no differences were found between cultivars for yield. The single row pattern was higher in percentage of fancy pods and total meat than the double row pattern. Seeding rate did not affect grades, however, the higher seeding rate had significantly higher yield and value ha–1. The cultivar X row pattern interaction was significant for yield and value. Row pattern did not affect yield and value of Florigiant, while both were higher for VA 81B in the double row system. This study indicated that peanut productivity can be increased by using the cv. VA 81B in the double row pattern, especially if used in combination with the high seeding rate.
Toxicity of Arrowleaf Clover Seed to Rhizobium trifolii1
Authors: Materon L.A. , Weaver R.W. 
Published: July 2010

AbstractArrowleaf clover (Trifolium vesiculosumSavi.) needs to be inoculated when sown in many fields in the southeastern USA. Survival of rhizobia on the seed following inoculation is critical for successful nodulation of the seedling. The effect the seed has on survival of the rhizobia has not been determined and may potentially be important to the success of inoculation. Seeds of subclover (T. subterruneumL.) and different genotypes of arrowleaf clover were placed on inoculated yeast mannitol agar medium to determine if the seed contained diffusable substances toxic to rhizobia. A thermostable, watersoluble diffusate was released from autoclaved and nonautoclaved seeds that inhibited the growth of many strains of Rhizobium trifolii. Seed‐coat disinfecting techniques that utilized aqueous solutions reduced toxicity of the seed and indicated that method of seed disinfection should be taken into consideration when conducting experiments on survival of rhizobia on seed. Two selections of ‘Amclo’ arrowleaf clover were demonstrated not to be toxic to R. trifolii. Additional research should be undertaken to identify the toxic substances in the seed and to determine their influence on survival of rhizobia applied to seed as an inoculant. The nontoxic seed would serve as a good control for such experiments and may prove to be useful to plant breeders in determining the genetic basis of the toxic substances.
Effects of N, Temperature, and Moisture Stress on the Growth and Physiology of Creeping Bentgrass and Response to Chelated Iron1
Authors: Schmidt R. E. , Snyder V. 
Published: July 2010

AbstractBentgrass (Agrostis palustris Huds.) turf often will improve in turf quality with applications of Fe during various times of the year in the transition zone even though soils contain sufficient levels of this trace element. In this study, 'Penncross' creeping bentgrass was grown in an environmental growth chamber in a factorial arrangement of three chelated Fe rates (iron diethylenetriamine pentaacetate, FeDTPA), two N levels, and three irrigation regimes. Turf was preconditioned to soil moisture stress by allowing soil moisture levels to dry to either 80,50, or 20% of the total unsaturated soil moisture (TUSM) before being irrigated to 100% TUSM. Ambient temperatures and photoperiods within the chamber were altered to simulate a late fall through mid‐summer growth cycle. Foliar applications of FeDTPA increased top growth during cool temperatures, but as temperatures were raised, FeDTPA applications depressed top growth. Net photosynthesis (NP) was also reduced by FeDTPA; however, dark respiration was unchanged. Foliar carbohydrates were increased with FeDTPA and appeared directly related to corresponding top growth reductions. Moisture stress preconditioning did not significantly influence plant response to applications of FeDTPA. However, repeated exposure to low soil moisture tended to reduce foilage yields and increase verdure. This indicated a more decumbent growth habit had resulted from repeated moisture stress. Net photosynthesis decreased as soil moisture levels declined. However, preconditioning turf to low soil moisture did not subsequently influence NP at either low or high soil moisture levels. Dark respiration (DR), was significantly lower for plants previously grown at the lowest irrigation regime regardless of subsequent soil moisture level. This reduction in DR may help account for the increased foliar carbohydrates associated with infrequent irrigation. This study did not show that turf response to FeDTPA was related to interactions with moisture stress. However, turf did adapt both morphologically and physiologically to repeated cycles of low soil moisture.
Cultivar, Nitrogen, and Soil Water Effects on Apex Development in Spring Wheat1
Authors: Frank A. B. , Bauer A. 
Published: July 2010

AbstractA better understanding of the growth and yield determining traits of spring wheat (Triticum aestivum L.) is important to development of improved cultivars, management practices, and growth simulation models. The objectives of this research were to evaluate cultivars, soil water content, and fertilizer N with respect to development of the main stem apex under field conditions. The experiment was conducted over 4 years on a Williams loam soil (fine‐loamy, mixed Typic Argiborolls). Cultivars of hard red spring wheat and durum wheat (T. turgidum L.) averaged 17.6 and 20.2 days, respectively, from emergence to apex double‐ridge formation. Cultivars of hard red spring wheat also differed significantly in accumulated growing degree days (GDD) to double‐ridge formation. Plant growth stage at apex double ridge as determined by the Haun scale, differed among hard red spring wheat cultivars. In general, cultivars that had a longer vegetative apex development stage had a higher Haun score at double‐ridge formation and also higher grain yields. Apex development of the hard red spring wheat cvs. Olaf, James, and Alex grown with two fertilizer N levels and three soil water levels was affected more by cultivar than by soil water content or fertilizer N level. The seven‐leaf cv., James, compared with eight‐leaf cvs., Olaf and Alex, generally had a shorter duration apex vegetative growth stage and spikelet development stage, required fewer GDD to reach double‐ridge and terminal spikelet stages, and developed double‐ridges and terminal spikelets at a lower Haun score. Stepwise regression analyses indicated that differences in grain yield and spikes/plant at harvest could be partly explained by duration of apex development to double ridges and the terminal spikelet expressed in days, accumulted GDD, and Haun score. Yield and spikes per plant were also associated with the number of spikelets/spike.
Foliar Applications of Nutrients on Maize. II. Physiological Responses1
Authors: Below F. E. , Lambert R. J. , Hageman R. H. 
Published: July 2010

AbstractDetailed analyses of plant and plant parts during the grain development period could establish mechanisms by which foliar fertilization, especially N, affects productivity of maize (Zea maysL.) hybrids. Field‐grown maize hybrids were sprayed at various stages of development with a mixture of nutrients (N‐P‐K‐S) in 1981 or urea in 1982 to determine whether foliar application of N would delay the remobilization of leaf N and leaf senescence thereby increasing productivity. In 1981, N‐P‐K‐S (12 kg N ha−1per treatment) was applied to plants of five hybrids at 7 days before and 12 days after anthesis. In 1982 urea (two equal applications for a total of 67 kg N ha−1) was applied to three hybrids B73 × Me17, Pioneer brand 3382, and Farm Services brand 854, at 12 and 6 days before anthesis and 9 and 15 and 25 and 32 days after anthesis to give treatments 1, 2, and 3, respectively. Soil type was Drummer silt loam (fine‐silty, mixed, mesic Typic Haplaquoll) in 1981 and a Flanigan silt loam (fine, montmorillonitic, mesic Aquic Arqiudoll) in 1982. The overall lack of effect of the fertilizer spray treatments on plant metabolism in 1981 was attributed to the small amount of supplemental nutrients applied. In 1982, changes in reduced N and nitrate of leaves, stalks, and whole plants were measured between anthesis and physiological maturity. These changes showed that the first urea treatment interfered with both nitrate uptake and assimilation for P3382 and assimilation for B73 × Mo17 and FS854. The second and third treatments had less effect on nitrate uptake and assimilation for all hybrids. The larger increases in stalk reduced N for all hybrids in response to the first urea treatment, compared to the second and third treatments, indicated that in the absence of a rapidly developing ear the stalk served as a storage reservoir for additional N. Urea applications caused no consistent increase, or alteration of the normal postanthesis decline, in the reduced‐N content of the leaves. The immediate decreases and trends in stalk carbohydrate contents show that the first two urea treatments interfered with the accumulation of carbohydrates, especially for P3382 and B73 × Mo l7. The observations that urea sprays did not increase N content of the leaves, decreased the accumulation of carbohydrates by the stalks, and appeared to interfere with indigenous N metabolism help explain the general ineffectiveness of foliar‐N treatments of maize.
Influence of Weed Control Treatments on Soybean Cultivars in an Oat‐Soybean Rotation1
Authors: Burnside Orvin C. , Moomaw Russell S. 
Published: July 2010

AbstractReduced tillage systems are being developed for the Great Plains that conserve limited moisture in order to improve soybean [Glycine max (L.) Merr.] cultivar response in this region. Fourteen soybean cultivars were grown in narrow rows using herbicides or tillage for weed control during the fallow period after oat (Avena sativa L.) harvest on an oat‐soybean rotation. Experiments were conducted at Concord, NE on a Colo silty clay loam (fine‐silty, mixed, mesic, Cumulic Haplaquolls) and at Lincoln on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic, Typic Argiudolls) during 1979 through 1982. The best broadleaf weed control occurred with ‘Gnome’, ‘Century’, ‘Weber’, and ‘Williams 79’ cultivars; also Gnome and Century had the best grass control as well as the lowest total weed yields. Early triazine injury was least (<30%) in Gnome, ‘Beeson 80’, ‘Elf’, ‘Wells II’, Weber, ‘Cumberland’, and Century. The highest yielding cultivars were ‘Mead’ and Century. Soybean cultivars generally yielded better on tilled vs. herbicide treated oat stubble, but the three cultivars showing the least difference in yields regardless of the prior fallow treatment were Cumberland, Beeson 80, and Weber. Cultivars selected for reduced tillage methods may differ from those used in conventional production systems.