bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plant Population Density and Row Spacing Effects on Soybean at Post‐Optimal Planting Dates
Authors: Boquet D. J. 
Published: July 2010

AbstractInformation on cultural practices for determinate soybean, Glycine max (L.) Merr., at post‐optimal planting dates is needed in the southern USA where planting is often delayed by weather or doublecropping. The objective of this study was to examine the effects of plant population density (PPD) on determinate soybean at two postoptimal planting dates in relation to interrow spacing, plant architecture, and yield components. A 3‐yr. soybean field study on Sharkey clay (very fine montmorillonitic, thermic, nonacid, vertic Haplaquept) was planted at post‐optimal dates of 20 June and 3 July. ‘Davis’ (MG VI) and ‘Braxton’ (MG VII) soybean were planted in 0.5 and 1.0 m row spacing (RS) at PPD at 6.4,13, 26, 38, 51 plants m−2 under irrigated and nonirrigated conditions. Yields were higher at the 0.5 m RS than at the 1.0 m RS, and were higher at the June date than at the July date. Highest yields at the June date (2.99 and 1.97 Mg ha−1) were with PPD of 38 and 13 plants m−2 at the 0.5 and 1.0 m RS, respectively. Yields were highest at the July date (2.45 and 1.53 Mg ha−1) with PPD of 51 and 26 plants m−2 at the 0.5 and 1.0 m RS, respectively. Increase in PPD up to 38 plants m−2 increased main stem length and decreased all other plant components. Decrease in main stem yield was proportionately smaller than the increase in PPD resulting in a net yield gain from higher PPD. Decrease in branch stem yield was proportionately greater than the increase in PPD resulting in a net yield loss from PPD increase. For determinate soybean planted at a 0.5 m RS an increase in PPD above that needed at optimal dates was necessary to obtain highest yields at post‐optimal planting dates. Soybean planted at the 1.0 m RS had much lower yield and was much less responsive to increase in PPD.
Water Deficit Development in Old and New Soybean Cultivars
Authors: Frederick J. R. , Wooley J. T. , Hesketh J. D. , Peters D. B. 
Published: July 2010

AbstractCrop productivity depends to some degree on a cultivar's capacity to maintain a high plant water status over a range of soil water conditions. We conducted this 2‐yr study to examine whether newer soybean [Glycine max (L.) Merr.] cultivars have more favorable leaf turgor potentials than older cultivars during the pod elongation and seed enlargement stages of crop development, and to determine whether the older and newer cultivars differ in leaf water potential components and stomatal resistances when grown under drought stress. Two older (‘Manchu’ and ‘Dunfield’) and two more recent (‘Clark 63’ and ‘Williams 82’) cultivars were field grown under irrigated (I) and nonirrigated (NI) conditions at Urbana, IL. Although large differences in soil water potential were found between the water treatments, afternoon leaf water potentials of the cultivars were decreased only an average of 0.14 MPa and afternoon leaf turgor potentials were not reduced as a result of the NI treatment. In both the NI and I plots, Manchu and Dunfield generally had lower and similar leaf turgor potentials, respectively, as did the modern cultivars during the day. Under NI conditions, greater stomatal closure occurred for the older cultivars than for the newer cultivars, indicating that the older cultivars are more efficient in conserving water under drought stress.
Production and Nutritive Value of Florigraze Rhizoma Peanut in a Semiarid Climate
Authors: Ocumpaugh W. R. 
Published: July 2010

Abstract‘Florigraze’ rhizoma peanut (Arachis glabrata Benth.) is a warmseason perennial forage legume that has received considerable research emphasis in Florida. However, little is known about its value outside of Florida. A field experiment was conducted on an established stand of Florigraze at Beeville, TX on a Parrita sandy clay loam (Clayey, mixed, hyperthermic, shallow Petrocalcia Paleustolls). Dry matter (DM) production, crude protein (CP) and in vitro digestible dry matter (IVDDM) of leaf blades and stem components were determined by sampling biweekly from June through January for each of two years. Treatments were total‐seasonal accumulated growth compared to regrowth of peanut defoliated in mid‐July or late‐August. A randomized complete block (RCB) design with three replicates was used, and 900‐cm2 areas were hand clipped to ground level for yield determinations. Typical for semiarid climate, rainfall was erratic and its distribution varied between years. Total‐seasonal DM accumulation of 8 to 10 Mg ha−1 was recorded each season. Rainfall influenced DM production patterns, percent leaf, stem IVDDM, and leaf and stem crude protein (CP). Rainfall and defoliation treatment had no effect on leaf IVDDM. Leaf IVDDM declined slowly during each year (−0.4 to −0.9 g kg−1 d−1) but exceeded 700 g kg−1 during the entire growing season. Florigraze loses leaves in response to drought stress. Autumn leaf production was unaffected by defoliation treatments. Leaf blade CP concentration was 1.7 to 1.9 times greater than that of stems. Because of leaf loss during late summer, spring and early summer production should be harvested in June or July. Forage production and nutritive value were sufficiently high, even under limited rainfall conditions, to warrant further investigation.
Harvest Management Effects on Alfalfa Yield and Root Carbohydrates in Three Georgia Environments
Authors: Brown L. G. , Hoveland C. S. , Karnok K. J. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) hay harvest management may need to be modified in the southeastern USA due to the mild winters and hotter summers compared with northern production areas. The objectives of this study were to evaluate the effect of three harvest treatments (10, 50, and 10% bloom until midsummer when one harvest was delayed until 50% bloom‐referred to as “summer rest” management) on herbage yield and seasonal trends of total nonstructural carbohydrates (TNC) in the roots of irrigated semidormant ‘Apollo’ and nondormant ‘Fla‐77’ alfalfa. The experiments were conducted for 2 yr in the Georgia Mountains on Bradson clay loam (Typic Hapludult, clayey, oxidic, mesic), Piedmont on Cecil sandy clay loam (Typic Hapludult, clayey, thermic, kaolinitic), and Coastal Plain on Greenville sandy clay loam (Rhodic Paleudult, clayey, thermic, kaolinitic). Alfalfa at all three locations gave satisfactory yield (12.7 Mg ha−1) when harvested at 10% bloom throughout the growing season including late fall. There was no advantage to either cultivar from harvesting at 50% bloom or allowing a summer rest period. Location effects were minimal. Root TNC concentrations were lowest in midsummer, greatest in late autumn, and decreased during winter. Root TNCs ranged from 200 to 560 g kg−1 for Fla‐77 and 150 to 580 g kg−1 for Apollo. There was no effect of cultivar or harvest management on root TNC concentrations. These results indicate that root TNCs are not a primary limiting factor for alfalfa hay production in the southeastern USA and that harvest can continue throughout the year with no adverse effect on forage yield.
Plant Density and Nitrogen Fertilizer Effects on Pearl Millet Production in Niger
Authors: Bationo A. , Christianson C. B. , Baethgen W. E. 
Published: July 2010

AbstractPearl millet (Pennisetum glaucum [L.] R. Br) is an important crop in many developing countries in West Africa and provides 80 to 90% of the food requirement for Niger. Farmers plant at a wide range of densities which may affect crop response to fertilizer. Studies were conducted for 3 yrs in a sandy soil in southern Niger to assess the effects of N fertilization (0–60 kg N ha−1) and plant density (5000–40 000 pockets ha−1, three plants per pocket) on millet yield and yield components. The effects of N and density on yield were influenced by midseason rainfall. With low midseason rainfall, highdensity planting reduced yield slightly and N had no effect. With average or above rainfall, N application and high plant density increased millet grain yield four‐ to fivefold. Nitrogen increased stover production 33% in a dry year and 100% in the wetter year. Plant density significantly affected stover yield only in 1983, a year with high early season rainfall. Increasing plant density tended to increase stover production in all years. Grain weight in 1983 decreased 14% when plant density exceeded 20 000 pockets ha−1. Nitrogen fertilizer doubled the number of heads per pocket at low plant densities when rainfall was normal or above. A plant density of 15 000 to 20 000 pockets ha−1 and N application of 30 kg N ha−1 in two splits achieved good yields in average and wet years, with only a small yield reduction in the drought year.
Root Distribution and Shoot Development in No‐Till Full‐Season and Double‐Crop Soybean
Authors: Coale F. J. , Grove J. H. 
Published: July 2010

AbstractDry matter accumulation by soybean [Glycine max (L.) Merr.] has been studied extensively, but few data are available on the relationship between shoot development and root distribution of no‐till full‐season and double‐crop soybean. Row spacing and K availability effects on shoot growth are also well understood, but have not been thoroughly integrated with measures of root growth. The objectives of this research were to characterize soybean root length density and distribution as well as shoot dry matter accumulation under no‐tillage soil management for: (i) full‐season and double‐crop planting dates, (ii) high and low soil K fertility levels, and (iii) narrow and conventional row spacings. Potassium fertility did not alter total shoot weight at R1, R5, or R7, but did alter shoot dry matter partitioning at R7. Later planting dates reduced shoot growth at R1, R5, and R7. Seed yield was increased by greater K availability, earlier planting and a narrower row width. Dry soil conditions during vegetative growth reduced root length density (RLD). As water became more available during reproduction, RLD increased. With adequate soil moisture, full‐season soybean RLD was greater than double‐crop soybean RLD. Surface soil RLD was greater when soil K fertility was low. Leaf abscission was delayed by K stress. In crop development periods when root growth was most active, the root length/shoot dry weight ratio was greater in double‐crop than in full‐season soybean. Double‐crop soybean produced relatively more root length in support of shoot growth than did full‐season soybean. Root growth was more affected by soil K availability and less affected by plant spacial arrangement and density than was shoot growth.
Utilizing Legume Cropping Systems to Reduce Nitrogen Fertilizer Requirements for Conservation‐tilled Corn
Authors: Oyer L. J. , Touchton J. T. 
Published: July 2010

AbstractThe need to reduce production costs has promoted a renewed interest in using legumes as a source of N for non‐leguminous summer crops. Development of legume cropping systems which will permit reseeding of winter cover‐crop legumes is a promising approach to reducing legume establishment costs. Field studies were conducted in Alabama for 4 yr on Wynnville sandy loam and Dothan fine‐sandy loam soils (fine‐loamy, siliceous, thermic, Glossic Fragiudults and Plinthic Paleudults, respectively) to determine the effects of both cash crop and winter cover‐crop legumes in cropping systems on N fertilizer requirements of corn (Zea mays L.) grown in a conservation‐tillage system. On the Wynnville soil, soybean (Glycine max L. Merr.) was more effective in providing early season N, and clover (Trifolium incarnatum L.) in providing late‐season N. The system with both soybean and clover resulted in an even more effective contribution of N to corn grain yield, and a higher yield level than that of continuous corn regardless of N fertilizer rate. On the Dothan soil, the benefits of cropping systems were not as pronounced, and the responses were eliminated by N fertilization, suggesting increased yields were due to N and not to a rotation effect. On both soils, in years of adequate and inadequate rainfall, the reseeding crimson clover system, in combination with a soybean‐corn rotation, consistently produced the highest yields of the systems studied, and provided a 68 to 159 kg N ha−1 fertilizer equivalent for corn.
Rotational Cropping Sequence Affects Yield of Corn and Soybean
Authors: Crookston R. K. , Kurle J. E. , Copeland P. J. , Ford J. H. , Lueschen W. E. 
Published: July 2010

AbstractThere are numerous reports of the beneficial effects of rotating corn (Zea mays L.) and soybean [Glycine max (L.) Merr.]. However, few studies have been specifically designed to document the important corn‐soybean rotation effect. The objective of this study was to determine the impact of various corn and soybean cropping patterns on the yield of both crops. The 9‐year field study conducted at two locations was managed for maximum production. Cropping sequences consisted of: continuous monoculture with the same cultivar; continuous monoculture with cultivars alternated; annual rotation of the two crops; and 1, 2, 3, 4, and 5 yr of monoculture following 5 yr of the other crop. Annually rotated corn yielded 10% better, and first‐year corn yielded 15% better than corn under monoculture. Annually rotated soybean yielded 8% better, and first year soybean yielded 17% better than soybean under monoculture. With monoculture of either crop, alternating two different cultivars annually resulted in the same yield as continuous cropping of just one cultivar. There were differences in the response of the two crops to increasing years of monoculture: the lowest corn yield was from second year corn; the lowest soybean yield was from extended monoculture. Total corn dry weight was affected by cropping sequence but soybean dry weight was not. Our data suggest that, from a yield standpoint, a superior cropping sequence for Minnesota would include at least three, and possibly more crops.
Hydraulic Conductivity of Cotton Roots as Influenced by Plant Age and Rooting Medium
Authors: Brar G. S. , McMichael B. L. , Taylor H. M. 
Published: July 2010

AbstractModels of water extraction by plant root systems often contain the basic assumption that hydraulic conductivity of the root system is a constant value. An experiment was conducted to determine if plant age or rooting medium environmental conditions affected hydraulic conductivity of cotton (Gossypium hirsutum L.) roots. Hydraulic conductivity was measured by the pressure outflow method at 12, 24, 36, and 48 d after planting (DAP) on roots grown in both hydroponics and sand. Hydraulic conductivity decreased 45% in nutrient‐solution‐grown and 57% in sand‐grown roots from 12 DAP to the mean of 24, 36, and 48 DAP. Hydraulic conductivity of sand‐grown roots was 4 to 10 times lower than that for roots grown hydroponically, whether conductivity was compared at equal DAP or at equal root length.
Development and Growth of Tropical Maize at Two Elevations in Hawaii
Authors: Manrique Luis A. , Hodges Tom 
Published: July 2010

AbstractDevelopment and growth response of maize (Zea mays L.) to an increase in temperature and daylength has been studied in temperate regions, but little is known of the effects of daylength on leaf number, leaf area development, and grain yield in tropical environments. A temperature‐by‐daylength experiment was conducted in the field on the Island of Maui, Hawaii (USA) at 282 and 640 m elevations during summer 1988 to examine the effects of daylength and temperature on leaf number, leaf area index (LAI), and grain yield of Pioneer hybrid X304C. Under high nutrient fertility and adequate water supply, plants were grown at natural daylength (12–13.5 h, control), control + 0.5‐h, 14‐, 17‐, and 20‐h daylengths. These daylengths were artificially produced by extending the natural daylength with 500‐W lamps. For a 97‐d period, mean maximum air temperatures were 26.8 and 27.8 °C while minimum air temperatures for the same period were 20.1 and 16.4 °C at the 282 and 640 m elevations, respectively. Longer days reduced mature leaf appearance rate and delayed tassel initiation and tasseling. Leaf tip appearance rate was unaffected by daylength but leaves took more thermal time for full expansion. Leaf area index in the 17‐ and 20‐ h daylengths was 7.0 at 77 d after planting, which was 1.8 times the LAI in the control and 14‐h daylengths. Physiological maturity in the 17‐h daylength was delayed by 33.5 and 38.5 d at 282 and 640 m, respectively. Maturity in the 20‐h daylength was delayed by 41.0 and 48.5 d at 282 and 640 m, respectively. Grain yields and harvest indices at both elevations decreased significantly with increasing daylength. Overall, warm temperatures at 282 m enhanced the adverse effects of daylength on grain yield.
Leaf Reflectance and Transmittance in Soybean and Corn
Authors: Walter‐Shea E. A. , Norman J. M. , Blad B. L. , Robinson B. F. 
Published: July 2010

AbstractLeaves have a major influence on canopy reflectance when they constitute the main spatial component in a vegetative canopy. Near normal‐incidence, directional‐hemispherical reflectance and transmittance of in situ individual leaves of soybean (Glycine max., Merr.) and corn (Zea mays, L.) were characterized as a function of wavelengths and growth. Spectral properties were measured in seven wavebands with an integrating sphere and prototype radiometer unit. Individual leaves periodically were monitored from emergence and unfolding through 47 d in soybean and 77 d in corn. Visible reflectance and transmittance decreased in soybean as leaves expanded, but increased after full leaf expansion. An opposite pattern was observed with soybean near‐infrared radiation (NIR) reflectance. Spectral properties varied little in mid‐ and upper‐canopy corn leaves with the exception of the green spectral region. Near constant values were attributed to the fact that corn leaves are fully expanded by the time they have fully emerged. Reflectance and transmittance properties of adaxial and abaxial surfaces differed by as much as an absolute 5% in soybeans while there were essentially no differences in corn. Differences in surface reflectance and transmittance in soybean were attributed to the dorsiventral morphology of soybean leaves. Reflectance and transmittance from adaxial and abaxial leaf surfaces may have to be considered in modeling soybean canopies while one surface should suffice to describe light interaction with corn canopy leaves.
Fertility and Weed Stress Effects on Performance of Maize/Soybean Intercrop
Authors: Weil Ray R. , McFadden Mary Ellen 
Published: July 2010

AbstractIntercropped corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] may produce more total yield per hectare than either grown separately, ie., land equivalent ratio (LER) =1. Low N fertility, limited moisture, and weed competition have each been reported to result in high land equivalent ratios. Thus it was hypothesized that intercropping advantages were greater under stress conditions. The objectives were to study the effects of soil fertility stress (F1 = low N‐P‐K,F2 = high N‐P‐K), weed competition stress (W1 = unweeded, W2 weeded), and four cropping systems (M2S, M1S, M2, S; where M2 = high density maize, M1 = low density maize, and S = soybean at normal density) on the performance of maize and soybean, and on the growth of weeds. ‘Cargill 921’ maize and ‘Union’ soybean were planted simultaneously in 1985 and 1986 in alternate rows spaced at 0.5 m on a typic Hapludult in Maryland. Land equivalent ratios and maize equivalent yields were calculated. Dry matter production was determined early in the season, and grain yield plus weed dry matter were determined at final harvest. LER values (mean of 1985 and 1986) ranged from 0.89 (W2F1,M2S) to 1.18 (W2F1M1S). The LER data showed that at high fertility levels, weed stress increased the relative advantage of intercropping. In addition, when plots were weeded, LER increased from 0.96 to 1.13 under fertility stress. Maize equivalent yields were calculated from the relative prices of maize and soybeans. The highest maize equivalent yields in all cropping systems in both years occurred under optimal conditions (W2F2).
Nitrogen and Dry Matter Accumulation, Remobilization, and Losses for Mediterranean Wheat during Grain Filling
Authors: Papakosta Despo K. , Gagianas A.A. 
Published: July 2010

AbstractDry matter and N accumulated by winter wheat (Triticum spp.) plants until anthesis are of importance under a Mediterranean climate because yield greatly depends on translocation of pre‐anthesis assimilates to grain. This field study was conducted to assess the effect of N fertilizer and cultivar on the amount of pre‐anthesis dry matter and N accumulated and remobilized, and the possible N losses. Two bread (T. aestivum L.) and two durum (T. durum Desf.) wheat cultivars were grown in a silty clay (Typic Xerorthent) in 1986 and 1987. Nitrogen at a rate of 150 kg ha−1 was applied before planting or 100 kg N ha−1 was applied before planting and then 50 kg N ha−1 at early boot stage. Cultivar dry matter translocation efficiencies ranged from 2.3 to 36.4%, N‐translocation efficiencies from 60.9 to 80.7%, and the contribution of pre‐anthesis assimilates to grain from 6 to 73%. Split N application reduced the contribution of pre‐anthesis assimilates to grain. High amounts of N (>200 kg ha−1), which had accumulated by anthesis led to net N losses at maturity, even with high yields (>6 Mg ha−1). No N losses were observed when N content at anthesis was lower than about 150 kg ha−1. However, at values ranging between these upper and lower limits, N loss was yield dependent (only yields >8 Mg ha−1 prevented N losses). Split N application tended to reduce N losses. Results indicated that the greater the amount of dry matter and N accumulated before anthesis, the higher the translocation rates of dry matter to grain and the greater the risk of net N losses at maturity.
Effect of Maize Maturity on Radiation‐Use Efficiency
Authors: Major D. J. , Beasley B. W. , Hamilton R.I. 
Published: July 2010

AbstractMaize (Zea mays L.) production has expanded into short‐season regions but it is not known whether the radiation‐use efficiency (RUE, g MJ−1)1 of new early hybrids differs from those grown in traditional maize‐growing regions. In this study, spectral reflectance measurements were used to derive estimates of photosynthetically active radiation (PAR) absorbed to compare the RUE of 10 maize hybrids that varied in adaptation from Iowa 110‐d relative maturity to the earliest 60‐d relative maturity hybrids commercially available. Reflectance measurements were made radiometrically in the visible and near‐infrared regions of the electromagnetic spectrum at approximately weekly intervals in 1985, 1986, and 1988. The 10 maize hybrids were grown at three densities at Lethbridge, Alberta, on an irrigated silty clay loam soil (Typic Haploboroll). The Scattering by Arbitrarily Inclined Leaves (SAIL) model of canopy reflectance was inverted to produce daily estimates of the fraction of absorbed PAR, p. Multiplying p by daily PAR irradiance gave daily estimates of absorbed PAR (APAR, MJ m−2), which were summed for the season. Radiation use efficiency was obtained by dividing whole‐plant yield at harvest by seasonal (emergence to harvest) APAR. Averaged over years, hybrids, and densities, RUE was 2.3 g MJ−1. Radiation‐use efficiency increased with population density across hybrids regardless of maturity. Seasonal RUE was lower than reported in the literature but there is evidence that chilling injury due to low night temperatures at the high elevation and semi‐arid location of the study reduced photosynthesis. The results suggest that spectral reflectance can be used effectively by breeders to identify hybrids that are more efficient users of PAR and that maize hybrids resistant to chilling injury may be needed at high latitudes.