bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of Seeding Variables on ‘Tifton 9’ Bahiagrass Establishment
Authors: Gates Roger N. , Mullahey J. Jeffrey 
Published: July 2010

Abstract‘Tifton 9’ possesses attributes similar to ‘Pensacola’ bahiagrass (Paspalum notatum Flügge var. saurae Parodi) including persistence, wide adaptation, and positive rotation effects for subsequent crops. Seed dormancy has been implicated as a cause of slow establishment of bahiagrass. Our objective was to evaluate dormancy‐reducing seed treatments on multiple seed lots with a range of seeding rates during spring, summer, or fall planting. Tifton 9 seed lots with high or low dormant seed fractions were planted without treatment, after solid matrix priming (SMP), or after accelerated aging (AA) at elevated temperature and humidity. Seed was planted during 2 yr at Tifton, GA (31°26' N, 83°35' W), or Immokalee, FL (26°27' N, 81°26' W), using seeding rates of 5.6, 16.8, or 50.4 kg ha−1. Tiller counts at 1 and 2 mo following planting, stand occupation the year following planting and dry matter harvested were obtained to monitor establishment. Seed lot had no influence on any variable evaluated. Initial stands were improved by SMP, indicating enhanced early emergence; however, SMP did not increase second‐year stands and forage yield compared with other seed treatments. Accelerated aging provided no advantage. Increasing the seeding rate resulted in greater emergence and second‐year stand coverage, but yield advantages were small. Response to planting season varied with year and location. A November freeze damaged October‐planted stands at Tifton in 1993. Stand establishment was hastened with a high seeding rate, but any advantage of high seeding rates was short lived. Seed treatments examined in this research provided little benefit, and it may be possible to reduce standard seeding rate recommendations without impairing long term establishment.
Interrupting Yield Depression in Monoculture Corn: Comparative Effectiveness of Grasses and Dicots
Authors: Porter Paul M. , Crookston R. Kent , Ford J. Harlan , Huggins David R. , Lueschen William E. 
Published: July 2010

AbstractIt has been well documented that monoculture corn (Zea mays L.) yields less than corn grown in certain rotations. This field study conducted from 1992 through 1995 investigated several agronomic crops, rotated with corn, for their relative effectiveness in interrupting the yield depression associated with corn monoculture. The study was conducted on a Webster clay loam (fine‐loamy, mixed, mesic Typic Endoaquolls) near Lamberton, MN. Corn grain yields were increased by a single‐year interruption with either alfalfa (Medicago sativa L.) or sunflower (Helianthus annuus L.) for each of 4 yr, with the exception of sunflower in 1992. Averaged cross 4 yr, corn yields were increased from 7.81 Mg ha−4 for continuous corn by 19 and 17% following a single year of alfalfa and sunflower, respectively. A single year of sorghum [Sorghum bicolor (L.) Moench], sorghum × sudangrass (intraspecific S. bicolor hybrid), or fallow did not improve corn yields compared with corn monoculture. This was true for each year, and when averaged across 4 yr, with the exception of the corn‐fallow rotation in 1995. Averaged across 4 yr, a 2‐yr interruption with sunflower followed by alfalfa increased corn yield by 22%. A 2‐yr interruption of sorghum followed by sorghum × sudangrass increased corn yield by 6% over that of monoculture. We conclude that the closely related grasses were relatively ineffective rotation crops for corn. Leguminous alfalfa and nonleguminous sunflower were equally effective in alleviating the corn monoculture yield depression.
Effect of Clipping on Yield and Nutritive Value of ‘Suerte’ Paspalum atratum
Authors: Kalmbacher Robert S. , Mullahey J. Jeffrey , Martin Frank G. , Kretschmer Albert E. 
Published: July 2010

Abstract‘Suerte’ Paspalum atratum Swallen, a recent introduction from Brazil, is a leafy, perennial bunchgrass that may provide good cattle weight gains during the summer on wet, acid soils. Yield and nutritive value of Suerte were evaluated by clipping at 10‐ and 25‐cm stubble heights every 20, 40, and 60 d over 240‐ to 248‐d growing seasons for 2 yr at Ona and Immokalee, FL. Annual dry matter (DM) yield was affected by year and location, with 14.8 and 13.9 Mg ha−1 produced at Ona in 1992 and 1993, respectively, and 8.3 and 6.0 Mg ha−1 at Immokalee in 1993 and 1994. Eighty percent of DM yield was produced during the rainy June to September period, with little growth in cool or dry months. Location and clipping intervals also interacted for annual DM yield, which was 10.6, 17.2, and 15.1 Mg ha−1 at Ona and 5.6, 8.9, and 6.8 Mg ha−1 at Immokalee for the 20‐, 40‐, and 60‐d clipping intervals, respectively. Stubble height had no effect on annual DM yield. Yield averaged 680, 2180, and 2740 kg ha−1 at each of the 12, 6, and 4 harvests for the 20‐, 40‐, and 60‐d clipping intervals. Tiller number per plant (measured at three dates during the growing season) and plant basal area at the end of the studies increased linearly as clipping interval increased. There was no loss of plants after 2 yr of clipping at Ona, but there was a 12% loss at Immokalee. Both crude protein (CP) (97, 82, and 52 g kg−1 for 20, 40, and 60 d, respectively) and in vitro organic matter digestion (IVOMD) (578, 552, and 520 g kg−1, respectively) decreased linearly over clipping intervals. These indices changed quadratically over the growing season with greatest values in April or May (91 g CP kg−1 and 600 g kg−1 IVOMD) and lowest values in August or September (72 g CP kg−1 and 510 g kg−1 IVOMD). When rotationally grazed, Suerte should have a 20‐ to 40‐d rest period between grazings to provide high DM yield and nutritive value.
Biomass Production and Nitrogen Uptake in Corn‐Ryegrass Systems
Authors: Zhou X. M. , Madramootoo C. A. , MacKenzie A. F. , Smith D. L. 
Published: July 2010

AbstractCropping systems, plant growth stages, and applied N fertilizer rates all directly affect N uptake. A 2‐yr study was conducted to evaluate the effects of cropping system [monocrop corn (Zea mays L.) and corn intercropped with annual ryegrass (Lolium multiflorum Lam.)] on dry matter (DM) production and distribution and on N uptake and allocation in the plants during the development of corn. Each of these corn systems was produced on a fine sandy loam (Typic Humaquept), using an application of 270 kg N ha−1 in each spring. Zero N (control) and conventional N rate (180 kg N ha−1) treatments were included for monocropped corn with conventional drainage. Plant tissues of all treatments were sampled at six‐leaf, tasseling, and mid‐grain filling stages, and after physiological maturity. In both years, DM production and N uptake of intercropped corn were lower than, or not different from, the monocropped corn (depending on growth stage). The total N uptake and DM production of the intercropping system (corn + ryegrass + weeds) were greater than those of the monocrop system. Application of 270 kg N ha−1 resulted in 20% less N recovery than 180 kg N ha−1 with monocropped corn production using free drainage. Both the corn‐ryegrass intercropping system and applied N rates altered the allocation of DM and N among different parts of the corn plants. The ryegrass and weeds were not able to take up enough of the extra N after the high N rate was applied for two consecutive years. The effect of precipitation on annual ryegrass growth was an important factor in N uptake by the intercropping system.
Resistance of Cotton with δ‐Endotoxin Genes from Bacillus thuringiensis var. kurstaki on Selected Lepidopteran Insects
Authors: Jenkins Johnie N. , McCarty Jack C. , Buehler Robert E. , Kiser Jack , Williams Curtis , Wofford Tom 
Published: July 2010

AbstractTransgenic cotton (Gossypium hirsutum L.) plants that express truncated versions of insect control protein genes cryIA (c) and cryIIA of Bacillus thuringiensis Berliner var. kurstaki (Bt) have been developed for managing lepidopteran pests. However, agronomic traits and pest resistance can vary among transformation events. We examined selected agronomic traits and resistance, in laboratory and field, against tobacco budworm [Heliothis virescens (F.)] and bollworm [Helicoverpa zea (Boddie)] for various transformation events of the cryIA(c) and cryIIA genes. Monsanto events with cryIIA were as resistant to tobacco budworm and bollworm as the M531 Bt event of cryIA(c), but showed some yield loss. Calgene events ST 807, ST 808, and ST 317 expressing cryIA(c) were similar to the M531 Bt event of cryIA(c) in control of tobacco budworm and bollworm. Backcrossed cultivars NuCOTN 33B and NuCOTN 35B from Delta & Pine Land Co. with event M531 Bt of cryIA(c) were highly resistant to tobacco budworm, producing more than 1400 kg ha−1 (vs. 0 on nontransgenic recurrent parents) under high levels of tobacco budworm infestation. These NuCOTN cultivars also yielded 450 to 550 kg ha−1 more lint than the recurrent parents under high levels of natural infestation of tobacco budworm in the insecticide control treatment; in the absence of tobacco budworm, NuCOTN yields were equal to or greater than for recurrent parents. The Paymaster Technologies lines with event M757 Bt of cryIA(c) were not pure for the gene, but showed excellent field resistance to tobacco budworm. Lines HX2 BG and HX3 BG showed resistance equal to the donor event M757 and yields equal to H1244. Reduced performance of event M757 in HX6 BG relative to other Paymaster lines with this event indicates a significant genotype × event interaction. Laboratory survival of bollworm after 7 d on transgenic leaves and squares was greater than survival of tobacco budworm; however, weight of surviving larvae of each species was only 10 to 15% of that on nontransgenic controls. Survival of fall armyworm [Spodoptera frugiperda (J.E. Smith)] at 7 d was only slightly lower than on nontransgenics, and weights were slightly lower. Careful evaluation of transgenic events and cultivars is necessary to ensure that the final cultivar is both resistant to target pests and has acceptable yield.
Mechanical Straw Mulching of Irrigation Furrows: Soil Erosion and Nutrient Losses
Authors: Shock Clinton C. , Hobson Joe H. , Seddigh Majid , Shock Byron M. , Stieber Timothy D. , Saunders Lamont D. 
Published: July 2010

AbstractThere is widespread concern about loss of sediments, NO‐3, and phosphate into surface water from irrigated farmlands. We studied the effects of 900 kg ha−1 wheat (Triticum spp.) straw, mechanically applied to irrigation furrows, on sediments and on N and P losses in the runoff. The field was on a Nyssa silt loam soil (coarse‐silty, mixed, mesic Xerollic Haplodurid) with 3% slope planted to onion (Allium cepa L.), and received 0, 50, or 200 kg P ha−1 incorporated to 0.1 m deep. Furrows were side‐dressed with 200 kg ha−1 N. Averaged across 17 irrigations, straw reduced runoff volume by 43%. Cumulative sediment lost after 17 irrigations was 17 Mg ha−1 for mulched and 333 Mg ha−1 for unmulched furrows. Straw also reduced NO‐3 and NH+4 losses in runoff solution and sediments. Total N losses during the first 6 irrigations were 33 kg ha−1 from mulched and 230 kg ha−1 from unmulched furrows. Straw effect on N loss was only through changes in the runoff volume and sediment loss. In contrast, as fertilizer P increased, PO4 concentrations in runoff solution and sediments also increased. Averaged across the first 6 irrigations, straw mulch reduced PO4 losses in the runoff solution by 59, 61, and 72%, for the 0, 50, and 200 kg P ha−1 treatments, respectively. Straw reduced PO4 losses in the sediment 15‐, 11‐, and 15‐fold for the 0, 50, and 200 kg P ha−1 treatments, respectively. Averaged across P fertilizer rates, total P lost after 6 irrigations was 18 kg ha−1 from mulched and 215 kg ha−1 from unmulched furrows. Mechanically applied straw mulch in irrigation furrows can substantially reduce soil erosion and N and P losses to surface water runoff.
Interhybrid Competition Affects Sunflower Character Expression
Authors: Johnson Burton L. , Schneiter Albert A. 
Published: July 2010

AbstractField researchers are confronted with selection of the proper plot design to assure agreement of small‐scale experimental plot results with large‐scale commercial field production. The objective of this research was to investigate the effect of plot design on expression of hybrid sunflower (Helianthus annuus L.) characters. Field studies were conducted in North Dakota at three dryland sites: Carrington, Fargo, and Prosper. lnterhybrid and intrahybrid competitive situations were attained by using one‐row or two‐row hybrid arrangements with three hybrids as possible borders. Competitive effects were determined on achene yield, achene oil concentration, achene weight, test weight, days to anthesis, head diameter, plant height, and leaf number. Plot achene yield was 20% greater when the border hybrid was a semidwarf than when border hybrids were of more conventional height. Border hybrid competitive influences on achene yield were approximately twice as great for one‐row as for two‐row arrangements. Other characters influenced by interhybrid competition were test weight, head diameter, and plant height. Characters not influenced by interhybrid competition included achene weight, achene oil concentration, days to anthesis, and leaf number. Plot border rows are recommended when evaluating characters subject to interhybrid competitive influences. An alternative approach is using one‐row or two‐row arrangements and grouping hybrids similar in plant height and maturity in the same field proximity.
Efficacy of Treatments for Delaying Senescence of Wheat Leaves: II. Senescence and Grain Yield under Field Conditions
Authors: Benbella Mohamed , Paulsen Gary M. 
Published: July 2010

AbstractLongevity of leaves directly influences grain yield of wheat (Triticum aestivum L.), but is greatly diminished by environmental stresses. The objective of these studies was to identify treatments that might delay senescence of wheat leaves and increase grain yield. ‘Nesma’ wheat was grown on a heavy clay soil at Meknes, Morocco, for two seasons, the first characterized by mild stress and the second by more severe stress from inadequate precipitation and high temperature. Three planting dates, two seeding rates, and foliar applications of NH4NO3, and KH2PO4 in randomized complete block designs were tested for efficacy in delaying senescence of leaves as measured by proteolytic activity, chlorophyll and protein concentrations, and grain yield. Advancing the planting date from early December, the optimum time, to November in the first year and delaying planting until January in the second year reduced grain yields in both seasons. Increasing the seeding rate from 200 to 400 kernels in m‐2 increased grain yields only in the second year, and foliar applications of 10 kg N as NH4NO3 ha−1 were ineffective in both years. Foliar applications of 5 to 10 kg ha−1 KH2PO4, in contrast, often increased grain yields by 1 Mg ha−1 or more. Senescence processes were enhanced by late planting because of high temperatures during maturation and by dense seeding because of interplant competition. Treatments that increased grain yields usually slowed senescence processes. Applying dilute solutions of KH2PO4 was most effective and, after further testing, might have merit for wheat in regions where drought and high‐temperature environmental stresses occur.
Field‐Scale Nitrogen Balances Associated with Long‐Term Continuous Corn Production
Authors: Karlen Douglas L. , Kramer Larry A. , Logsdon Sally D. 
Published: July 2010

AbstractExcessive residual soil NO3‐N indicates economic inefficiency for producers and increases the potential for nonpoint leaching of N to water resources. Our objective was to construct an approximate fieldscale N budget for continuous corn (Zea mays L.) grown on deep loess soils in four 30‐ to 60‐ha field‐scale watersheds in western Iowa. Preplant and postemergence soil NO3‐N levels were determined for the 0‐ to 30‐cm, 30‐ to 60‐cm, and 60‐ to 90‐cm depths in April before N fertilizer was applied and again at the V6 growth stage. A simple root‐zone water balance and N removal by corn grain were determined. The 4‐yr average showed approximately 100 kg ha−1 of NO3‐N in the upper 90 cm of the root zone before an average of 168 kg of fertilizer N ha−1 was applied. Grain removal accounted for 30 to 70% of the fertilizer N. There were significant differences in grain yield and N removal among the four watersheds. Factors contributing to those differences included different fertilizer rates, tillage practices, and application times. During the four study years, an average of 50% of the applied N was available for leaching, denitrification, and/ or NH3 volatilization. High levels of residual soil NO3‐N following continuous corn production coupled with steady percolation of precipitation that infiltrated but was not used by the corn crop appear to be the two major factors supplying NO3‐N to groundwater baseflow that enters streams draining the watersheds. Based on the seasonal water balance, the most successful N management strategies will be those that minimize the amount of residual NO3‐N remaining in the soil profile at the end of the growing season.
Winter Wheat Yield Depression from Legume Green Fallow
Authors: Vigil Merle F. , Nielsen David C. 
Published: July 2010

AbstractIncreases in N fertilizer costs have caused some farmers to consider the use of a legume during the fallow phase of a wheat‐fallow system as an alternative N source for dryland wheat. Farmers need to know how this system will affect winter wheat (Triticum aestivum L.) production and economic returns. The objectives of this research were (i) to determine the effect of legume green fallow on subsequent winter wheat yields and economic returns and (ii) to determine optimal legume termination dates during the legume phase. Wheat yields following three legumes [Austrian winter pea, Pisum sativum L. subsp. sativum var. arvense (L.) Poir.; spring field pea, P. sativum L.; and black lentil, Lens culinaris Medikus] were compared with wheat yields following fertilized traditional summer fallow. Legume biomass, biomass N, and water use were measured at four termination dates during the green‐fallow phase of the rotation. Wheat yields following the annual legume were reduced, compared with traditional summer fallow, by 400 kg ha−1 at the earliest legume termination date and by at least 1050 kg ha−1 at all other dates. Economic analysis indicates that in drier than normal years, that returns are maximized when the legume is not grown during the fallow phase. In 1996, a wet year, returns were maximized when the legume was terminated at the second termination date or after 70% of the potential maximum legume water use. We found that 88% of the variability in winter wheat yield could be explained by legume water use the previous year. In general, the competitiveness of legume green fallow with winter wheat fallow is highly weather‐dependent and inconsistent. At current fertilizer costs, legume N (in this system) was too expensive to be considered a reasonable alternative to chemical fertilizer.
Patterns of Seed Softening in Subterranean Clover in a Cool, Temperate Environment
Authors: Evans Pedro M. , Smith Fiona A. 
Published: July 2010

AsbtractsEnvironmental conditions affect seed softening patterns of annual legumes. These patterns have not been well established for cool, temperate environments. This work examines the effect of genotype and of growing and softening environments on the short‐term loss of dormancy in subterranean clover (Trifolium subterraneum L.) during the summer and early autumn. Burrs of six cultivars and one accession of subterranean clover that varied widely in maturity and hardseed level were placed to soften on the soil surface, over the summerautumn period, under two contrasting environments in western Victoria, Australia: Hamilton and Telopea Downs. There were significant differences (P < 0.05) in the rate of hardseed breakdown both among cultivars and at the two locations. At the cooler site, Hamilton, the levels of residual hardseed after the summer averaged 75% (over all cultivars and growing sites), compared with 66% at Telopea Downs. There was no interaction between cultivar and location of softening. At the end of the period of field exposure the ranking from lowest to highest residual hardseed was ‘Enfield’ < ‘Leura’ = ‘Gosse’ < ‘Dalkeith’ < ‘York’ = SE008 = ‘Nungarin’. High levels of embryo dormancy in Leura indicate that this cultivar has the capacity for delayed germination via embryo dormancy. The results suggest that in cool temperate environments high seed banks of subterranean clover can be achieved due to a lower percentage of seed softening, which in turn means a potentially greater long‐term persistence of subterranean clover and the possibility of conducting 1:1 pasture‐crop rotations in a rainfall zone where consistently high grain yields may be expected.
Desiccation and Germination of Grain Sorghum As Affected by Glufosinate
Authors: Bovey Rodney W. , Dahlberg Jeffery A. , Madera‐Torres Pablo , Senseman Scott A. , Miller Frederick R. 
Published: July 2010

AbstractPreharvest desiccants are needed to reduce moisture content of grain sorghum [Sorghum bicolor (L.) Moench] for earlier harvest to preserve seed quality and quantity. Objectives of this study were (i) to examine the desiccant activity of glufosinate [2‐amino‐4‐(hydroxy‐methylphosphinyl)butanoic acid] applied at several rates to grain sorghum at different seed moisture levels in contrasting environments and (ii) to determine the effect of glufosinate on germination and seedling growth of the treated crop. The soil at College Station (east‐central Texas), was a Ships clay (very‐fine, mixed, active, thermic, Chromic Hapludert); at Mayagüez, PR, a Coto clay (very‐fine, kaolinitic, isohyperthermic Typic Hapludox). Glufosinate was evaluated because of its contact herbicidal properties and limited systemic activity. In both Texas and Puerto Rico, glufosinate was applied at 0, 0.56, 1.1, or 2.2 kg ha−1 to grain sorghum. Leaves and seed were sampled at 0, 1, 2, and 3 wk after treatment (WAT) for grain and leaf moisture. Seed was collected at 2 and 3 WAT for germination and growth studies. Glufosinate at all three treatment rates dried seed of the grain sorghum hybrid ATx638/Tx2783 in Texas from >350 g kg−1 grain moisture at application to a storable moisture of <120 g kg−1 at 2 WAT, at which time untreated grain moisture was 150 g kg−1. Glufosinate rate did not affect grain moisture except at the high glufosinate rate at 1 WAT. Leaf moisture reduction was glufosinate rate‐dependent, but all treatments significantly reduced leaf moisture content at 1 WAT. Germination and seedling growth were not affected by glufosinate treatment. Grain desiccation rate under a tropical environment (Puerto Rico) was slightly slower than in Texas, but leaf moisture reduction was rapid and reached <300 g kg−1 by 1 WAT from initial leaf moisture contents of 500 or 770 g kg−1. Germination was not adversely affected by glufosinate.
Tests of Some Methods for Detecting Antibiotics in Soil
Authors: Witkamp M. , Starkey R. L. 
Published: July 2010

AbstractVarious methods of testing soils for antibiotics were compared using soils to which antibacterial substances (penicillin, streptomycin, chloramphenicol) or antifungal substances (cycloheximide, candicidin, nystatin) had been added. Chloramphenicol, penicillin, and cycloheximide could be tested by direct diffusion from soil through a cellulose film into assay agar. All of the antibiotics could be determined in soil‐agar mixtures. Whith this method, some antibiotics were more active in nearly neutral media than in acid media. The antifungal antibiotics and streptomycin showed decreasing activity against certain test organisms with an increase in the amount of colloidal material in the soil. There was little or no such effect with chloramphenicol and penicillin.