bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Water Deficit Stress on Competitive Interaction of Peanut and Sicklepod
Authors: Moreshet Samuel , Bridges David C. , NeSmith D. Scott , Huang Bingru 
Published: July 2010

AbstractOne of the potentially deleterious effects of weeds on crop production is competition for water. In this study, competitive interactions between peanut (Arachis hypogaea L.) and sicklepod (Senna obtusifolia L.) were investigated. The two species were grown alone and mixed in a glasshouse in 118‐L barrels (0.65 deep and 0.48 m wide) filled with a Molena sandy soil (sandy, mixed, thermic Psammentic Hapludults). Treatments were either continuously irrigated (WET) or periodically dried (DRY). Measurements included daily soil water content (τ), continuous water uptake, stomatal conductance (g), leaf xylem water potential (Ψ1) and leaf osmotic potential. Water uptake and g were well correlated to τ. With both species, water uptake, g, and Ψ1 all declined when τ in the top half of the barrel was approximately one‐third of the available water (5.8 to 7.4% v/v; equivalent soil water potential, Ψs, −0.20 and −0.08 MPa). The τ‐values at which water uptake and g began to decline (here called inflection points) were always lower for peanut (5.9 to 6.1%; Ψs = The τ‐values at) than for sicklepod (7.4 to 7.5%; Ψs = − 0.08 to − 0.07 MPa). Ψ1 was similar for the two species. The inflection points of water uptake, g, and Ψ1 for both species were always higher when related to τ‐values in the bottom half of the barrel (8.6% to 13.1%, Ψs = − 0.04 and − 0.005 MPa) than when related to τ in the top half of the barrel. This response occurred even though the fraction of fine root length density in the bottom half was more than 45% of the total fine root length density in the DRY treatment of sicklepod and both species mixed. Significant osmotic adjustment was detected in both species following water deficit stress. At full turgor, leaf osmotic potential of all WET treatments reached − 0.99 MPa; at zero turgor, it reached −1.12 MPa. For the DRY treatments, leaf osmotic potential at full turgor dropped to −1.22 and −1.24 MPa in sicklepod and peanut, respectively; at zero turgor, it dropped to − 1.31 and − 1.34 MPa in sicklepod and peanut, respectively, but the difference between species was not significant. As the soil dried, water use by peanut mixed was significantly higher than sicklepod mixed. It appears that peanut can use more water under water deficit stress and can recover faster than sicklepod in a mixed community of the two species.
The Quest for Balance in Crop Modeling
Authors: Monteith John L. 
Published: July 2010

AbstractCrop models habitually run ahead of the measurements needed for rigorous calibration and validation. The treatment of key physiological processes is often very uneven, and the availability of microcomputers encourages modelers to develop complex schemes providing output that is unqualified by errors or uncertainties. Crop models are potentially powerful tools, but they should be used in a more disciplined way.
Aerodynamic Characteristics of Standing Corn Stubble
Authors: Sauer Thomas J. , Hatfield Jerry L. , Prueger John H. 
Published: July 2010

AbstractMaintenance of crop residues on the soil surface is promoted as a management practice for reducing soil erosion by wind and water. Crop residue on the soil surface, however, also influences turbulent exchange processes that affect surface water and energy balances. At present, there are very limited data on the aerodynamic properties of residue‐covered surfaces. The objective of this research was to derive estimates of the aerodynamic properties (momentum roughness length z0, zero‐plane displacement d, and drag coefficient Cd) of fields with standing corn (Zea mays L.) stubble. Wind speed and air temperature measurements were made at six heights above two no‐tillage fields near Ames, IA, in the spring and fall of 1994 and in the spring of 1995. Both sites had standing corn stubble approximately 0.3 m tall at a density of greater than 60 000 stalks ha −1 and nearly 95% residue cover. An iterative, least‐squares linear regression technique was applied to wind profiles obtained under neutral atmospheric conditions to determine z0, d, and the friction velocity (u.). Mean values of z0 and d for each of the three measurement periods varied from 11.8 to 24.3 and 119 to 169 mm, respectively. The ratios z0/hs and d/hs, where hs is the mean stubble height, averaged 0.058 and 0.53, respectively, for all profiles. The magnitude of zo and d and their weak dependence on wind speed are consistent with turbulent flow over a surface with sparse, rigid roughness elements. The z0 and Cd were higher for the fall measurement period, suggesting that the loose, fresh residue presented a comparatively rough surface that was then smoothed by weathering and compaction beneath snow.
Long‐Term Tillage, Crop Rotation, and Nitrogen Fertilizer Effects on Wheat Yield under Rainfed Mediterranean Conditions
Authors: López‐Bellido L. , Fuentes M. , Castillo J. E. , López‐Garrido F. J. , Fernández E. J. 
Published: July 2010

AbstractThe combined long‐term effects of tillage method and crop rotation on crop yield have not been studied in rainfed systems under Mediterranean climates. A field study was conducted from 1988 to 1994 to determine the effects of tillage (TILL), crop rotation and (ROT) N fertilizer on wheat (Triticum aestivum L.) yield in a rainfed Mediterranean region. Tillage treatments include no tillage (NT) and conventional tillage (CT). Crop rotations were wheat‐sunflower (Helianthus annuus L.) (WS), wheat‐chickpea (Cicer arietinum L.) (WCP), wheatfababean (Vicia faba L.) (WFB), wheat‐fallow (WF), and continuous wheat (CW), with N fertilizer rates of 50, 100, and 150 kg N ha−1. A split‐split plot design with four replications was used. Differences in rainfall during the growing season had a marked effect on wheat yield. Amount of rainfall during the vegetative period for wheat (November‐February) was highly correlated with yield because of the high water‐retention capacity of Vertisols (Typic Haploxerert). In dry years, wheat yield was greater under NT than under CT; the opposite was true in wet years. The TILL ✕ ROT interaction was also significant in the drought years; the wheat yield under NT was greater for CW and the WFB and WF rotations than under CT. Wheat yields ranked by crop rotation were: WFB > WF >> WCP > WS >> CW. Wheat did not respond to N fertilizer when rainfall was below 450 mm during the growing season. Using these results strategies can be developed for establishing the N fertilizer rate applied to wheat as a function of rainfall, the preceding crop, and residual N in soil in order to optimize wheat yield and reduce nitrate pollution to groundwater.
Tillage and Crop Residue Effects on Corn Production in Quebec
Authors: Burgess M. S. , Mehuys G. R. , Madramootoo C. A. 
Published: July 2010

AbstractReduced tillage is often recommended to decrease soil degradation and erosion associated with intensive row cropping. This study assessed the effects of different tillage and crop residue levels on corn (Zea mays L.) yields and related factors on a 2.4‐ha site in southwestern Quebec over a 3‐yr period. The soil, a Typic Endoaquent, consisted of sandy loam or loamy sand (mean depth, 46 cm) overlying clay, with subsurface drains at the 1.2‐m depth. Treatments, begun in fall 1991, consisted of no‐till (NT), reduced tillage (RT; disked in fall and spring), and conventional tillage (CT; moldboard‐plowed in fall, disked in spring), in combination with two crop‐residue levels: no residue (− R; grain and stover removed at harvest, as for silage corn) and with residue (+ R; stover left on site at harvest, as for grain corn). High crop‐residue mulches resulted from NT ÷ R (77–97% of soil surface covered), RT + R (45–92%), and at times NT −R (8–35%), potentially protecting the soil from erosive forces. Seedling emergence was delayed (1992, 1993) or partly suppressed (1994) in NT + R, and was also delayed in CT + R in 1992 and 1993, and in CT−R and RT ÷ R in 1993. Final populations were affected only in 1994. In − R (silage) plots, yields with NT and RT were either greater (1992) or the same as their CT counterparts. On + R (grain) plots, grain, stover, and total yields were lower with NT in 1992 and 1994, due in part to difficulties in planting through the residue mulch, while RT reduced grain, stover, and total yields in 1992 and stover and total yields in 1993. Thus, for silage‐corn production, NT and RT may offer economically viable alternatives to CT, although the use of disking for a RT system provides almost no protective residue cover. In continuous grain corn, high residue buildup with NT and RT requires special attention to seeding technique or yield losses may result.
Corn Yield is Equal in Conventional, Reduced, and No Tillage after 20 Years
Authors: Kapusta George , Krausz Ronald F. , Matthews Joseph L. 
Published: July 2010

AbstractReduced tillage has increased dramatically over the past several years and is expected to continue to increase in the future. Continuous no‐till may become a popular tillage system with growers to facilitate compliance with government programs to control soil erosion. The objective of this research was to evaluate the long‐term effects of four tillage systems and five fertilizer regimes on corn (Zea mays L.) yield. A 20‐yr continuous‐corn tillage ✕ fertility study was conducted from 1970 to 1990 on an Ebbert silt loam (fine‐silty, mixed, mesic Argiaquic Argialbolls), an imperfectly drained soil at the Belleville Research Center, Belleville, IL. Starter fertilizer did not increase corn height within a tillage system. Height was greater in no‐till compared with conventional till (moldboard plow), reduced till (chisel plow), or alternate till (2 yr no‐till, 1 yr moldboard plow) with or without a starter fertilizer. There was no difference in population among tillage systems due to fertilizer treatment. Corn population was lower in no‐till compared with conventional till regardless of fertilizer treatment. Starter fertilizer did not increase yield in any tillage system. Corn yield averaged 5 to 7% lower in no‐till compared with conventional till or reduced till where a starter fertilizer was applied. There was no difference in yield among tillage systems when NPK was broadcast. Corn yield was equal in conventional till, alternate till, reduced till, and no‐till with fertilizer applied broadcast on an imperfectly drained soil. Continuous no‐till with an imperfectly drained soil does not reduce corn yield.
Groat Yield and Plant Stand Structure of Naked and Hulled Oat under Different Nitrogen Fertilizer and Seeding Rates
Authors: Peltonen‐Sainio Pirjo 
Published: July 2010

AbstractGrain yield of naked oat (Avena sativa var. nuda L.) is lower than that of hulled oat mainly due to reduced seedling emergence, fewer spikelets per panicle, and more grains per spikelet. This study was conducted in the field to evaluate management possibilities of reducing these undesirable traits of naked oat by adjusting seeding rate and N fertilizer application rate, thereby increasing groat yield. Studies were conducted at the Viikki Experimental Farm, University of Helsinki, Finland, in 1993 and 1994. Two N fertilizer rates (80 and 120 kg N ha−1) and five seeding rates (400, 500, 600, 700, and 800 viable seeds m−2) were used. Grain and groat yield and 24 morphophysiological traits of three naked and two hulled lines were compared. The highest yielding naked line, Rhiannon, produced approximately 9% higher groat yield and 4% more groat per panicle than the most popular Finnish hulled oat line, Veli. The same groat yield in naked lines and Veli, when measured across all treatments, may result from modest ( ≈ 2%) differences in seedling emergence. Use of seedling emergence instead of germination percent to determine planting density, and seed treatment with a fungicide, possibly contributed to uniform emergence. Naked lines tillered slightly more than hulled lines, and tiller contribution to leaf area index was higher at lower seeding rates. Use of high seeding rates reduced both number of spikelets and grains per panicle without having consistent effects on number of tertiary grains per spikelet. Number of grains per spikelet was not affected by N fertilizer rate. There was no marked advantage for using higher seeding rates and N fertilizer rates for naked lines. However, the capacity of naked lines to produce panicles through tillering compensates for reduced seedling emergence and an undesirably high grain number associated with a low number of spikelets per panicle.
Intermittent Shade Effect on Gas Exchange of Cotton Leaves in the Humid Southeastern USA
Authors: Bauer Philip J. , Sadler E. John , Frederick James R. 
Published: July 2010

AbstractConvective cumulus clouds intermittently shade growing plants on most days during the summer months in the southeastern USA. Previous research indicates a significant delay in the recovery of stomatal conductance (gs) of cotton (Gossypium hirsutum L.) leaves following a period of shade. Our objective was to determine the effect of shade on leaf net CO2 exchange rate (CER) and gs of three cotton cultivars. We monitored CER and gs of greenhouse‐ and field‐grown cotton before, during, and after shading plants for up to 9 min at photosynthetically active radiation (PAR) levels of <300 μmol quanta m−2 s−1. The three cultivars had the same gas exchange response to shade. With the imposition of a 6‐min shade on greenhouse‐grown plants at 7 weeks after planting (WAP) gs of uppermost fully expanded leaves fell 43%. Two weeks later, a 6‐min shade reduced gs of uppermost fully expanded leaves by 97%. Under field conditions, a 9‐min shade reduced gs by 35% early in the cutout period (cessation of vegetative growth) in 1992 and 42% late in the cutout period in 1994. Under both greenhouse and field growing conditions, the low PAR levels with shade reduced CER to near 0 μmol CO2 m−2 s−1. Recovery of CER to preshade levels after the shade was removed coincided with the rate of recovery of gs. In the greenhouse‐grown plants, recovery of CER to preshade levels following 6 min of shade did not occur until 7 min (at 7 WAP) and 10 min (at 9 WAP) after the shade was removed. Field‐grown leaves needed only 4 min to recover to preshade levels of CER and g2 following 9 min of shade. The results suggest that, following a brief shade period, field‐grown cotton leaves reacclimate within 4 min, while leaves on greenhouse‐grown plants may take longer.
DIALLEL‐SAS: A SAS Program for Griffing's Diallel Analyses
Authors: Zhang Yudong , Kang Manjit S. 
Published: July 2010

AbstractDiallel mating designs are generally used to obtain estimates of genetic effects for a fixed set of parental lines (fixed effects) or to estimate general combining ability (GCA) and specific combining ability (SCA) variance components from a set of randomly chosen parental lines (random effects) from multiple‐environment experiments. Published computer programs for diallel analyses do not provide a partition of F1 hybrids ✕ environments interaction into GCA ✕ environments, SCA ✕ environments, and reciprocal ✕ environments components for Griffing's Methods 1 and 3, and into GCA ✕ environments and SCA ✕ environments components for Griffing's Methods 2 and 4. Existing programs for Methods 1 and 3 also do not partition reciprocal effects into maternal and nonmaternal effects. This paper reports the development of a comprehensive SAS program (DIALLEL‐SAS) for partitioning interactions between environments (years and/or locations) and F1 hybrids. DIALLEL‐SAS can be run on any microcomputer with SAS, as well as on mainframe computers installed with SAS via UNIX or TSO. The DIALLEL‐SAS output includes (i) mean squares for environments, F1 hybrids, F1 hybrids ✕ environments, GCA, SCA, reciprocal, maternal, nonmaternal, GCA ✕ environments, SCA ✕ environments, reciprocal ✕ environments, maternal ✕ environments, nonmaternal ✕ environments, (ii) estimates of GCA and maternal effects for each parental line, and (iii) estimates of SCA, nonmaternal, and reciprocal effects for each F1 hybrid.
Recovery of Fertilizer Nitrogen Applied to Burley Tobacco
Authors: MacKown Charles T. , Sutton Tommy G. 
Published: July 2010

AbstractThe high cash value of burley tobacco (Nicotiana tabacum L.) may lead to ineffective excess fertilization of the crop. The effects of N management on fertilizer N use efficiency by burley tobacco and recovery of residual fertilizer N by a winter cover crop were determined. Tobacco was grown in 1993 at two locations with 0 to 336 kg N ha−1 broadcast applied before transplanting or 168 kg N ha−1 sidedressed at onset of rapid growth (≈ 5 wk after transplanting). Seasonal recoveries of 15N‐depleted fertilizer N were determined in aboveground tissues of the tobacco crop. The amount of labeled fertilizer N recovered at harvest (29 to 124 kg N ha−1) increased with increasing amounts of N applied, but fertilizer N use efficiency was constant at 36.6 ± 0.9% for broadcast applications. Sidedress N enhanced labeled fertilizer N recovery (43 to 54% of applied N, depending on location), even though total aboveground dry matter was equal to or 12% less than that of plants grown with the same amount of N applied by broadcast. Recovery of residual labeled fertilizer N in the cover crop ranged from 2 to 7% of applied N and was greatest for the highest amount of N applied. Fertilizer N recoveries estimated by the difference method equaled those of the 15N method at 5 wk after transplanting. At 13 wk after transplanting, the difference method, particularly for applications of 84 and 168 kg N ha−1, overestimated fertilizer N recoveries relative to the 15N method, and is unlikely to provide an accurate measure of fertilizer N use by burley tobacco across a wide range of N applications. Reducing the amount of broadcast applied fertilizer to give a 10% decrease in air‐cured leaf yield would decrease the unaccounted fertilizer N by 80 to 115 kg N ha−1, depending on location. As compared with broadcast application of fertilizer N before transplanting, drill banding the N at about 5 wk after transplanting would equal or further decrease unaccounted amounts of fertilizer N.
Subsoil Nitrate Uptake by Grain Pearl Millet
Authors: Menezes Romulo S. C. , Gascho Gary J. , Hanna Wayne W. , Cabrera Miguel L. , Hook James E. 
Published: July 2010

AbstractPearl millet [Pennisetum glaucum (R.) Br.] is a high‐quality grain crop that can that can be grown without irrigation during hot, dry summers in the southeastern United States. The N rate required for optimum pearl millet grain yield varies widely in published studies, possibly because of variability in residual soil N from the subsoil. Field studies were conducted in the southern Coastal Plain at Tifton, GA, on a Tifton loamy sand (fine‐loamy, siliceous, thermic Plinthic Kandiudult) with nitrate accumulations near subsoil plinthite. The objective was to determine if pearl millet can extract N from acidic, relatively impermeable subsoils. Nitrate N (1 M KCl‐extractable) was 4 mg kg−1 in the surface 0.6 m, 1 mg kg−1 in the next 0.6 m, and 6 mg kg−1 from 1.2 to 1.5 m. We fertilized pearl millet field plots with two levels of N (0 and 168 kg ha−1) and studied root development during the growing seasons in 1993 and 1994. Soil cores were taken 40 d after planting to a depth of 1.2 m, separated into 0.3‐m depth segments, and root length density was measured. Roots were found in the deepest segments. Nitrogen fertilization increased the proportion of the root length density found in the surface soil in one year. We also injected 15N as 60% atom l5N‐enriched KNO3 at a depth of 1 m at 30 and 40 d after planting. At physiological maturity, atom % 15N abundance in the plants ranged from 10.1 to 12.0 where 15N was injected and was near natural abundance where no 15N was injected. These results indicate that pearl millet can extract N from 1 to 1.2 m in an acidic and impermeable subsoil.
Modeling a Rye Cover Crop and Subsequent Soybean Yield
Authors: Wagner‐Riddle Claudia , Gillespie Terry J. , Hunt Leslie A. , Swanton Clarence J. 
Published: July 2010

AbstractSoybean [Glycine max (L.) Merr.] can be no‐till seeded in the spring following a killed rye (Secale cereale L.) cover crop. A shortage of rain can affect soybean yields, depending on the timing of killing and the amount of mulch produced. Our main objective was to incorporate the effect of a rye mulch on soil water content into a soybean growth model (SOYGRO). The use of a wheat (Triticum aestivum L.) growth model (CERES‐Wheat) for rye mulch production calculations and SOYGRO for predicting yields under no‐mulch and mulch conditions were evaluated. The water balance subroutine of SOYGRO was modified to account for the effect of a rye mulch on soil water content due to mulch albedo, rain interception, and transmissivity of solar radiation. Data from previous experiments at Delhi (Psammentic Hapludalf soil), and Woodstock (Typic Hapludalf) in Ontario, Canada, were used to evaluate these modifications and yield predictions. Mulch production was described well by CERES‐Wheat (r2 = 0.96). The modified SOYGRO model improved soil water content calculations relative to the original model (r2 = 0.67 vs. 0.58, root mean square error = 0.028 vs. 0.064 m3 m−3). Simulated soybean yields were within 1 SD of measured values. In agreement with field measurements, the simulated effect of mulch did not increase soybean yields, and modification of SOYGRO to include mulch effects did not change yield predictions (r2 = 0.83 vs. 0.81) when no prolonged drought occurred. The simple mulch model incorporated into SOYGRO was adequate to model the effect of rye mulch on soybean growth. The use of CERES‐Wheat and the modified SOYGRO model in sequence under hypothetical drier weather conditions was demonstrated.
Cropping and Tillage Systems for Dryland Grain Production in the Southern High Plains
Authors: Jones Ordie R. , Popham Thomas W. 
Published: July 2010

AbstractLow precipitation and high evaporative potential limit yields of dryland crops in the semiarid Southern High Plains. Improved residue management can reduce evaporation and improve water conservation. We compared no‐tillage (NT) and stubble mulch (SM) residue management effects from 1984 to 1993 on leveled minibenches at Bushland, TX, using winter wheat (Triticum aestivum L.)‐fallow (WF), continuous wheat (CW), wheat‐sorghum [Sorghum bicolor (L.) Moench]‐fallow (WSF), and continuous sorghum (CS) systems. The soil was a Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll). Our objective was to quantify and compare soil water storage, crop water use, and grain production in order to identify the most water‐efficient production system. Relative to SM management, NT management of wheat residues increased average soil water contents at planting of the next crop by 22 mm with WSF, 15 mm with WF, and 29 mm with CW; it was not as effective with sorghum residues. Mean grain yields were not affected by residue management on any cropping system, because the additional water stored with NT management was slight in relation to seasonal evapotranspiration. Cropping systems had major effects on grain yield and production. Fallow systems (WSF, WF) normally resulted in higher yields than the corresponding annual cropping system (CW, CS). However, when grain production was adjusted to an annual basis including fallow time, the CS system was most efficient at using precipitation, producing 92% more grain than WSF, 240% more than CW, and 320% more than WF. Grain production was more than twice as great with sorghum than with wheat, due to greater biomass production and a 33% greater harvest index. Although wheat is the major dryland crop in the Southern High Plains, sorghum seems much better adapted to the region's predominant pattern of late spring‐summer rainfall.