bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forage Yield and Nutritive Value of Elephantgrass as Affected by Harvest Frequency and Genotype
Authors: Woodard K. R. , Prine G. M. 
Published: July 2010

AbstractElephantgrass (Pennisetum purpureum Schum.) is known throughout much of the wet tropics for its prolific growth and usage as a forage for ruminants. In a 3‐yr study conducted on a welldrained, infertile soil (loamy, siliceous, hyperthermic, Grossarenic Paleudult) and under subtropical conditions near Gainesville, FL, the response of this forage to three harvest frequency regimes was measured. Genotypes evaluated were four tall elephantgrasses (PI 300086, ‘Merkeron’, N‐43, and N‐51), a dwarf elephantgrass (Mott), and a semi‐dwarf Pennisetum glaucum (L.) R. Br. × P. purpureum Schum. hybrid (Selection 3). Forage dry matter (DM) yields for Merkeron, N‐43, and N‐51 did not differ. For these three genotypes, 3‐yr mean DM yields (1986‐1988) were 24.3, 21.1, and 17.0 Mg ha−1 yr−1 for one, two, and three harvests per year, respectively. Two‐year mean (1986‐1987) crude protein (CP) concentrations for all four tall genotypes were 40.3, 57.5, and 75.7 g kg−1 DM while in vitro digestible organic matter (IVDOM) concentrations were 399, 492, and 555 g kg−1 organic matter (OM) for one, two, and three harvests per year, respectively. For Mott, 3‐yr mean DM yields were 11.8, 11.8, and 11.7 Mg ha−1 yr−1 for one, two, and three harvests per year, respectively. Two‐year mean CP concentrations were 52.7, 69.4, and 85.6 g kg−1 DM whereas IVDOM concentrations were 396, 549, and 580 g kg‐1 OM, respectively. Merkeron, N‐43, N‐51, and Mott persisted well. In PI 300086 plots harvested multiple times, major stand losses occurred over the 1987–1988 winter. Selection 3 did not persist. Adapted elephantgrass genotypes can persist in colder regions of the subtropics and should provide substantial quantities of forage.
Choosing the Best by Ranking and Selection
Authors: Lund R. E. , Cherry J. S. , Martin J. M. 
Published: July 2010

AbstractSelecting the best treatment(s) is a common problem in agricultural research. The usual procedure is to rank all treatment means and to claim the best treatment(s) are the highest (or lowest) subset found not to differ significantly according to a traditional multiple comparison (TMC). A least significant difference (LSD) procedure is applied most frequently. Our objective is to introduce a somewhat new methodology called simply ranking and selection (R&S) by way of agronomic examples and to illustrate why R&S may be preferred over TMC for selecting the best. Steps similar to those when using TMC to select the best are applied by R&S but it uses tabled values distinctive to several criteria for specifying “bestness.” We concentrate upon both identifying the one best treatment and selecting the subset containing that one best, but unspecified treatment. The R&S method assumes outright that the true unknown treatment means (population means) are unequal. Probabilities are derived from available information about that inequality and pertain specifically to the likeliness of making a correct selection. Conversely, LSD was developed upon the framework of testing the explicit hypothesis of equality for two specific population means and the most evident probability pertains precisely to incorrectly rejecting that equality. Probabilities associated with correctly identifying means, which are not equal, are considered only indirectly by LSD. Two examples from agronomic literature are used to demonstrate R&S methodology. We are recommending that agricultural researchers continue to use TMC for the broad general purpose for which it was designed, but furthermore, we are suggesting they become familiar with R&S and apply it for the specific purpose for which it was designed.
Temperature Effects on Cotton Canopy Growth, Photosynthesis, and Respiration
Authors: Reddy V. R. , Baker D. N. , Hodges H. F. 
Published: July 2010

AbstractThe ecological range of temperature conditions where cotton (Gossypium hirsutum L.) is commercially grown frequently exceeds the temperature range of available data. To predict growth, development, and responses of the primary physiological processes to those conditions, data at both lower and higher temperatures are needed. Cotton plants were grown in naturally lit, temperature‐ and CO2− controlled chambers. Plants grown at near‐optimum temperatures (30 and 35 °C day temperature) fixed twice as much CO2 at high photosynthetically active radiation during the fruiting period as did plants growing at 20 °C. Growth exhibited similar differences due to temperature during the boll‐filling period. Plants with heavy fruiting load partitioned less to vegetative structures. Most plants grown at 35/25 °C day/night temperatures and all those grown at 40/30 °C had serious flower survival problems. No fruits were harvested from the plants grown in the 40/30 °C chamber and only a few from those grown in the 35/25 °C chamber. Gross photosynthesis, canopy light utilization efficiency, and canopy conductance were found to be highly variable from day to day. This variability should be considered by investigators measuring short‐term CO2 exchange rates. Respiration rates of cotton plants were 45% higher during the first hour of dark than during the rest of the night. These data suggest that carbohydrate is more readily available for respiration during and immediately after the light period than later in the dark period.
Nutrient and Carbohydrate Partitioning in Sorghum Stover
Authors: Powell J. M. , Hons F. M. , McBee G. G. 
Published: July 2010

AbstractAlthough petroleum fuels have been abundant during the past decade, alternative energy sources are needed for the long term. Sorghum [Sorghum bicolor (L.) Moench] stover has been demonstrated to be a potential biomass energy source. Complete above‐ground crop removal, however, can result in soil degradation. Differential dry matter, nutrient, and carbohydrate partitioning by sorghum cultivars may allow management strategies that return certain stover parts to the field while removing other portions for alternative uses, such as energy production. A field study was conducted to determine N, P, K, nonstructural carbohydrate, cellulose, hemicellulose, and lignin distributions in stover of three diverse sorghum cultivars of differing harvest indices. Determinations were based on total vegetative biomass; total blades; total stalks; and upper, middle, and lower blades and stalks. Concentrations of N and P were higher in blades than stalks and generally declined from upper to lower stover parts. Large carbohydrate and lignin concentration differences were observed on the basis of cultivar and stover part. Greater nutrient partitioning to the upper third of the intermediate‐ and forage‐type sorghum stovers was observed as compared to the conventional grain cultivar. Stover carbohydrates for all cultivars were mainly contained in the lower two‐thirds of the stalk fraction. A system was proposed for returning upper stover portions to soil, while removing remaining portions for alternative uses.
Ontogeny and Water Use of No‐Tillage Sorghum Cultivars on Dryland
Authors: Unger Paul W. 
Published: July 2010

AbstractGrain sorghum [Sorghum bicolor (L.) Moench] yields are strongly influenced by soil water content at planting and use of that water during the growing season. Sorghum on Pullman soils (fine, mixed, thermic Torrertic Paleustolls), however, usually does not use water from as deep in the soil as other crops, thus possibly not attaining its full yield potential. This study was conducted from 1986 to 1989 to determine whether eight sorghum hybrid cultivars grown under no‐tillage conditions on a dryland Pullman clay loam at Bushland, TX, differed with respect to water use depth, growth, yield, yield components, total water use, and water use efficiency. The hybrids were Pioneer 8493; Funk 1498 and 499; DeKalb DK‐46, DK‐42, and DK‐41Y; and Richardson 9112 and Sprint. Determinations included precipitation and soil water use, water use efficiency, grain and stover yield, harvest index, panicles harvested, panicle/seedling ratio, seed per panicle, seed per unit area, and weight per seed. Based on water content measurements, there was no conclusive evidence that any cultivar depleted soil water deeper or to a greater extent than the others, but the highest yielding cultivar (DK‐41Y, mean yield of 5.22 Mg ha−1) was among the highest water users each year, suggesting that this cultivar uses water effectively for grain production. Multiple regression analyses involving all cultivars showed that grain yield was most strongly affected by weight per seed, but this was closely followed by seed per unit area. Other variables significantly related to grain yield were planting seed (number per gram), panicle/seedling ratio, panicles harvested, and stover yield. Overall, this study showed that high grain yields are achieved by cultivars that use available water supplies or that respond to improved water conditions during the growing season to produce vigorous plants capable of converting photosynthate into high quality grain. Although deeper and more intensive soil water use is desirable, sorghum improvement programs should not neglect other traits that can also result in more efficient grain production.
Effect of Soil Surface Treatments on Runoff and Wheat Yields under Irrigation
Authors: Stern R. , Van Der Merwe A.J. , Laker M.C. , Shainberg I. 
Published: July 2010

AbstractIn arid and semi‐arid regions, where soil structure is unstable, surface runoff due to seal formation reduces irrigation water use efficiency. This study was conducted to determine the efficiency of surface treatments in reducing runoff and increasing wheat crop productivity. Surface runoff from wheat plots on a non‐sodic, silty clay loam soil (Rhodudalf silty clay loam), sprinkler irrigated with a good quality irrigation water, was collected using flumes and collection boxes. Percentages of runoff were 36.1% of the total irrigation during the growing season for the control (Ct), 12.8% for phosphogypsum (PG), 1.4% for polyacrylamide plus PG (PAM), and 1.1% for pitting plus PG (Pt) treatments. The mulching effect of the growing canopy did not reduce runoff during consecutive irrigations as the season progressed. Water content in the profile was correlated with the amount of water that infiltrated into the soil. The crop biomass production in the Pt and PAM treatments was significantly higher than the PG and Ct treatments (8.81 and 7.91 vs. 6.41 and 5.47 Mg ha−1, respectively). The Pt and PAM treatments also gave significantly higher grain yield (3.66 and 3.02 vs. 2.25 and 2.12 Mg ha−1, respectively). The Pt, PAM, and PG treatments resulted in significantly higher irrigation water use efficiency (IWUE) than the Ct. The PAM is the least known treatment and is given special attention in this study. In regions where water is scarce and costly, improving the efficiency of irrigation by tillage or soil ameliorants should be considered.
Effect of Mono and Mixed Culture of Tall Fescue and Birdsfoot Trefoil on Yield and Quality
Authors: Beuselinck P.R. , Sleper D.A. , Bughrara S.S. , Roberts C.A. 
Published: July 2010

AbstractGrowth habit of grass and legume cultivars may affect their competitiveness, yield, and herbage quality in grass‐legume mixes. The objective of this research was to examine herbage yield and quality of mixed cultures of tall fescue (Festuca arundinacea Shreb.) genotypes and birdsfoot trefoil (Lotus corniculatus L.) cultivars with contrasting growth habits. High (HLAER) and low (LLAER) leaf‐area‐expansion‐rate tall fescue populations and prostrate (‘Dawn’) and upright (‘Viking’) birdsfoot trefoil cultivars were used. Eight treatments comprising monocultures of the four entries (HLAER, LLAER, Dawn, Viking) and 1:1 mixed cultures of each possible interspecific combination of the entries were transplanted into field plots in June 1983 and harvested at a 3‐ or 6‐wk frequency in 1984 and 1985. Mixed cultures were hand‐separated into tall fescue and birdsfoot trefoil components prior to drying. Herbage dry weight (DWT), in vitro dry matter digestibility (IVDMD), crude protein (CP), neutral detergent fiber (NDF) and acid detergent fiber (ADF) were measured. Mixtures of tall fescue and birdsfoot trefoil were moderately compatible regardless of growth form of species. When grown in mixed cultures, yield of tall fescue and birdsfoot trefoil was reduced by interspecific competition. Growth form of either species did not appear to affect DWT of mixed cultures. Herbage yield of tall fescue and birdsfoot trefoil was influenced by harvest frequency. Yield and quality of tall fescue‐birdsfoot trefoil mixed cultures can be greater than monocultured tall fescue.
Yield Losses in Winter Wheat Caused by Low‐Density Cereal Aphid Populations
Authors: Kieckhefer R.W. , Gellner J.L. 
Published: July 2010

AbstractIn most autumns on the Northern Plains of the USA, low population densities of several species of cereal aphids feed on seedling winter wheat, Triticum aestivum L., for a month or more. The objective of this research was to determine the influence of that feeding on the growth and yield of ‘Rose’ winter wheat. Experiments were conducted by confining non‐viruliferous (barley yellow dwarf virus) greenbug, Schizaphis graminum (Rondani), at precisely maintained population densities of 2, 4, 6, 8, 10, and 15 aphids per plant, bird cherry oat aphids, Rhopalosiphum padi (L.), at densities of 10 or 15 aphids per plant, or Russian wheat aphids, Diuraphis noxia (Mordvilko), at 5, 10, 15, and 20 aphids per plant on seedling plants for 30 d in an environmental chamber at 10°C (to simulate mean October temperature in the field), 12 h day/night. The results showed that the threshold for significant yield loss under these environmental conditions was at the 10 aphids per plant level for the bird cherry oat aphid and the Russian wheat aphid, and 15 aphids per plant for greenbug. Yield losses caused by any of the aphid species were in the range of 35 to 40% at 15 aphids per plant. Although the visible injury to plants caused by the feeding of the greenbug and the Russian wheat aphid was striking, the bird cherry oat aphid was as damaging to yield as the other two species in this study.
Crop Sequence Affects Nutrient Composition of Corn and Soybean Grown under High Fertility
Authors: Copeland P. J. , Crookston R. K. 
Published: July 2010

AbstractAlthough crop rotation may change soil mineral status, particularly N, there may also be a rotation effect beyond that which can be explained by soil mineral status alone. Research has shown that leaf mineral‐composition can vary between crop sequences at high fertilizer levels. We hypothesized that the rotation effect observed in longterm sequences of corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] might be due to an increased nutrient concentration, not just an increased accumulation. A corn‐soybean rotation study in Minnesota managed at high nutrient fertility was used to test our hypothesis. The high management level was appraised by soil test levels. Corn and soybean sequences evaluated were monoculture, first year, second year, and annually‐alternated. These crop sequences were evaluated for their effects on plant nutrient concentration, accumulation, or both. The growth stage at which differences in plant nutrient concentration or accumulation might affect final yield was also evaluated. A positive effect of rotation on yield was observed in both crops. Shoot concentrations and total accumulations of N, P, and K were higher in first year corn compared to monoculture, suggesting that the increased corn yield associated with rotation may have been due to a general improvement in plant nutrition. Cropping sequence had less of an effect on soybean nutrient concentration than corn. Nutrient accumulation in soybean was not generally affected by crop sequence.
Conventional vs. No‐Till Corn Following Alfalfa/Grass: Timing of Vegetation Kill
Authors: Smith M. A. , Carter P. R. , Imholte A. A. 
Published: July 2010

AbstractProducers who plant no‐till corn (Zea mays L.) following hay or pasture are concerned about herbicide application timing and efficacy to kill perennial vegetation, plant residue effects on corn growth, and optimal corn planting date. A field study was conducted near Arlington, WI, from 1985 to 1988 to evaluate the influences of (i) conventional (CT) vs. no‐till (NT), (ii) fall vs. spring kill of perennial vegetation, (iii) late‐April vs. mid‐May planting, and (iv) three hybrid maturities on corn following legume/grass sod. Parameters measured include residue cover, soil temperature, and soil moisture after planting; corn emergence percentage; days to emergence; days to silk; grain moisture; and grain yield. Tillage by time of vegetation kill interactions were important for corn development and grain yield. Few differences were observed between fall and spring plowing in CT. For NT, however, chemically killing perennials in the spring compared to in the fall resulted in greater residue cover after planting (6–90% vs. 40%), and cooler and drier soil in the seed zone after planting. Emergence was delayed 1.5 to 4.0 d with spring‐kill NT and subsequent development was delayed throughout the growing season. Spring‐kill NT resulted in lower grain yields (−10 to −50%) compared to fall‐kill NT in 3 of 4 yr. For NT, when perennial vegetation was killed in the fall and corn was planted early, plant growth and grain yields were comparable to those for CT. Fall‐kill NT produced consistent growth and yield responses during the study years, whereas spring‐kill NT results were more variable, with poorest results in the drought of 1988.
Colonization of Soybean by Mycorrhizal Fungi and Spore Populations in Iowa Soils
Authors: Khalil S. , Loynachan T. E. , McNabb H.S. 
Published: July 2010

AbstractMycorrhizae, a mutualistic association between fungi of the family Endogonaceae and higher plants, have been studied extensively in the greenhouse, but much less is known about the natural ecology of these fungal‐plant associations in field soils. A better understanding of the mycorrhizae of agronomic crops is needed because of their potential involvement in systems of sustainable agriculture. This study reports on the extent of root colonization by mycorrhizal fungi, the distribution of mycorrhizal fungal spores in the rhizosphere, and the mycorrhizal fungal genera associated with soybean [Glycine max (L.) Merr.] in 15 Iowa soils. Results indicated that soybean roots from most soils, in spite of some soils having very high soil‐test P levels, were extensively colonized (60–100%) by vesicular‐arbuscular mycorrhizal (VAM) fungi. Colonization was determined by evaluating the percentage of root segments with VAM fungi. The average colonization of plant roots from all soils was 89%, and the average Bray P1 soil‐test value was 60.3 mg kg−1 (values greater than 30.5 are considered by the Iowa State Soil Testing Laboratory to be very high). Abundant colonization was unexpected in these high‐P fertility soils because most authors report extensive colonization to occur mainly in plants growing in soils of low fertility. The VAM fungal spores were quite common in all rhizosphere soils sampled and ranged from 66 to 998 spores 100 g−1 soil. Total spore counts were significantly different among soil series (P < 0.001) and within soil series (P < 0.01). A negative correlation (P < 0.05) was found between soil organic matter, P, and VAM fungal colonization. For VAM fungal genera (Glomus, Gigaspora, Acaulospora, and Scutellospora) were found associated with soybean rhizosphere soil. Among these, Glomus was the most abundant.
Seed Germination Response of Four Southwestern Range Grasses to Equilibration at Subgermination Matric‐Potentials
Authors: Hardegree Stuart P. , Emmerich William E. 
Published: July 2010

AbstractSeed priming at subgermination water potential has been shown to enhance the germination response of a wide number of plant species. Optimal priming conditions for germination enhancement are usually found to be at the least negative water potential that prevents radicle emergence. Equilibration of seeds at more negative water potentials may have detrimental effects on germination relative to control treatments. Seeds of Bouteloua curtipendula (Michx.) Torr., Cenchrus ciliaris L., Eragrostis lehmanniana Nees, and Panicum coloratum L. were equilibrated over the matric potential range of −1.6 to −17.5 MPa and germinated over the matric potential range of 0 to −1.6 MPa. Matric‐priming at −1.6 MPa frequently increased germination percentage and rate at reduced water potential. Matric‐priming at water potentials more negative than −1.6 MPa had a less positive and sometimes detrimental effect on germination relative to control treatments. Germination response of primed seeds showed a tendency toward, but not necessarily achievement of, control levels at the most negative priming‐water potentials.
Fertilizer Placement and Tillage Effects of Nitrogen Assimilation by Wheat
Authors: Rao S.C. , Dao T.H. 
Published: July 2010

AbstractLittle information is available concerning tillage effects on seasonal N accumulation and their effect on wheat yield. Field studies were conducted to determine the effects of fertilizer N placement and tillage practices on the reduction and assimilation of N in winter wheat (Triticum aestivum L.) during 1984 through 1987 on Renfrow silt loam (fine, mixed, thermic, Uderic, Paleustolls) near El Reno, OK. Fertilizer N (50 kg ha−1) and P (60 kg ha−1) including 4 kg N ha−1 and 11 kg P ha−1, with the seed was applied in the fall. In the spring, an additional 50 to 100 kg N ha−1 as ammonium nitrate was either broadcast or placed in narrow bands on the soil surface. Nitrate reductase (NR) activity, NO3‐N, and crude protein (CP) content of wheat plants were determined periodically during spring growth until anthesis, and final grain and straw yield and their CP contents were determined. The NR activity in early spring was slightly greater during early spring in plants grown under no‐till when compared to conventional till in 1985 and 1986, whereas the reverse was observed in 1987. Increased NR activity was paralleled by an increase in vegetative CP. Placement of N in a narrow band on the soil surface in the spring improved NR activity levels, but the effect of N placement had little effect on CP concentration. Grain yield followed NR activity levels and was 36% higher in no‐till in 1985, similar in 1986, but 51% lower in 1987 than conventionally tilled plots. Placement of N in narrow bands increased N‐use efficiency by increasing N reduction and assimilation; but had little effect on the yield of grain and straw in both tillage methods.
Photosensitization in Lambs Grazing Switchgrass
Authors: Puoli J. R. , Reid R. L. , Belesky D. P. 
Published: July 2010

AbstractHepatogenous photosensitization has been recorded in herbivores grazing a number of Panicum species in different areas of the world. This condition was observed in weaned and suckling lambs (Ovis sp.) grazing switchgrass (Panicum virgatum L. cv. Cave‐in‐Rock) in Morgantown, WV, during the abnormally hot, dry summer of 1991. The first cases occurred in June, 35 d after initiation of grazing. Further cases occurred with a new group of lambs 12 d after their introduction to switchgrass pastures in late July. Of a total of 104 lambs, 17 showed photosensitization and eight died. Symptoms were similar to those reported for ‘geeldikkop’ in sheep and hepatotoxicity was confirmed by changes in blood metabolites. Mature ewes were not affected and no signs of photosensitization were noted in suckling lambs grazing switchgrass during the previous year under more normal temperature and rainfall conditions. Photosensitization does not appear to have been observed in cattle on switchgrass but monitoring of younger animals grazing this Panicum species seems desirable.