bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maize Shoot and Root Response to Root Zone Saturation during Vegetative Growth
Authors: Lizaso Jon I. , Ritchie Joe T. 
Published: July 2010

AbstractExcess water adversely affects 12% of the world's soils. In rainfed cropping areas, heavy rainfalls may produce transient soil saturation. Better understanding of plant growth under transient soil water saturation or high water tables is needed for effective simulation models. In particular, improved functions are needed to estimate maize (Zea mays L.) response to root zone saturation of various durations and at different stages of plant growth. This 2‐yr study was conducted in Michigan in a field facility where the water table could be independently managed on several 2.1‐ by 1.5‐m2 plots. Saturated conditions were imposed for 4 or 8 d in early (leaf tip 5–6) or late (leaf tip 10–12) vegetative growth. Shoot growth measurements included leaf extension, biomass, leaf area, leaf senescence, stomatal conductance, and photosynthesis. Roots were observed and counted at several soil depths, using minirhizotron tubes. Root zone saturation had a major impact on almost all aspects of plant growth and yield. Measured yield for the control was 153 g plant−1 in 1991. Plants exposed to root zone saturation yielded about half of the control yield, primarily because of a reduction in kernel number per ear. Biomass growth was reduced through reduced leaf area expansion, increased leaf senescence, and reduced photosynthesis. Root numbers at the 15‐ and 40‐cm depths decreased soon after soil saturation, but root growth increased rapidly about 10 d after the saturated treatments ended and final root numbers were about the same as the control by season's end. Loss of leaf area growth was never recovered, and green leaf area reduction due to senescence further decreased plant growth. Responses to early and late saturation were about the same. Doubling the saturation period reduced final biomass by only an additional 10%, showing the adaptive responses of maize for survival of saturation. Nonetheless, crop yields may be dramatically reduced.
Model Analysis of Sorghum Response to Nitrogen in Subtropical and Tropical Environments
Authors: Sinclair Thomas R. , Muchow Russell C. , Monteith John L. 
Published: July 2010

AbstractNitrogen fertilization is important in achieving high sorghum [Sorghum bicolor (L.) Moench yields. Under semiarid conditions, however, the response to N is confounded by seasonal differences in water availability. A simple, mechanistic model was developed to interpret measurements of the growth and yield of sorghum at different levels of N and water supply. The structure of the sorghum‐N model was equivalent to a previously developed maize‐N (Zea mays L.) model, including the N uptake function, which depends on thermal units. The sorghum‐N model was developed considering experimental results obtained in the tropical climate of Katherine, Australia. After adjusting coefficients to describe leaf and grain development for sorghum instead of maize, the model simulated crop N uptake, growth, and grain yield. Without any further changes in the model, sorghum grown in the subtropical climate of Lawes, Australia, with grain yields ranging from 121 to 886 g m−2, was well simulated by the model. A third set of data obtained in an irrigation‐N application experiment at Hyderabad, India, was compared against model results. After adjusting the coefficients that describe the development of the cultivar and the soil organic content at this location, the model produced results comparable to experimental results. Analysis of the model results led to two interesting hypotheses concerning the experiment at Hyderabad: (i) the irrigation level of the well‐watered treatment appeared to be inadequate to avoid drought stress at the end of the cropping season, and (ii) there was seemingly about 4 g N m−2 of soil N unavailable to the crop in each of the irrigation treatments. Overall, the sorghum‐N model proved useful in interpreting and analyzing field measurements of development, growth, and yield of sorghum grown under diverse conditions.
Chicory Productivity, Forage Quality, and Response to Nitrogen Fertilization
Authors: Collins Michael , McCoy Joe E. 
Published: July 2010

AbstractChicory (Cichorium intybus L.) shows potential for use in grazing systems. Information is needed regarding the productivity and quality of chicory forage in midlatitude states of the USA. Forage yield and quality of chicory under several levels of N fertilization were determined in a Kentucky field experiment. Plots were established during late spring on a silt loam soil (fine‐silty, mixed, mesic Typic Paleudult) and received 0, 50, 100, 150, or 200 kg ha−1 of fertilizer N annually in two equal portions. Treatments were arranged in a randomized complete block design with four replicates. Herbage was harvested four times each year at 5‐wk intervals. With N fertilization, chicory produced maximum dry matter yields of 7.8 and 5.6 Mg ha−1 in 1992 and 1993, respectively. Increasing N level produced linear increases in first‐harvest yields and linear or quadratic increases at the third harvest, during midsummer, but N effects persisted only during the first growth period after application. Chicory forage was high in moisture: ≥850 g kg−1 in first‐harvest forage, which often increased with increasing N level. Chicory remained almost completely vegetative, and forage quality was consistently high. Nitrogen concentration averaged 22.9 and 22.3 g kg−1 in 1992 and 1993, respectively, and was affected by N fertilization primarily at the first harvest. Chicory forage exceeded 640 g kg−1 in vitro dry matter disappearance and remained below 400 in neutral‐detergent fiber concentration throughout the study. Chicory established rapidly and persisted well. Nitrogen‐fertilized chicory produced high midseason yields of highquality forage, suggesting that this species could supplement cool‐season grasses. The high rate and extent of N recovery found for chicory warrants further research to determine optimum N fertilization regimes.
Energy Balance Simulation for Surface Soil and Residue Temperatures with Incomplete Cover
Authors: Aiken Robert M. , Flerchinger Gerald N. , Farahani Hamid J. , Johnsen Karen E. 
Published: July 2010

AbstractKnowledge of the effects that crop residue architecture has on exchange processes at the soil surface can extend the applicability of soil and water balance modules. Our objectives were to evaluate the feasibility of using a numerically reduced soil‐residue energy boundary condition module, compatible with the USDA‐ARS Root Zone Water Quality Model, and to compare the accuracy of calculated values against measurements. We developed a Penman‐type energy balance module, PENFLUX, which solves for surface temperatures of a soil slab and a single flat residue layer, adjusting for aerodynamic resistances of standing residue stems. It provides surface boundary conditions for simulations of energy transfer in a one‐dimensional soil profile. PENFLUX simplifies iterative solutions by simplifying radiation, convection, and soil heat algorithms. We collected hourly radiation data; air, soil, and residue temperatures; and wind profile data after wheat harvest on a level Nunn clay loam soil (fine, smectitic, mesic Aridic Argiustoll) (1997 soil series reclassification). Model parameterization avoided fitting model calculations to measurements, as inputs were measured at the site or referenced from literature. PENFLUX calculations exhibited a low degree of random error for dry soil and residue conditions, though systematic bias in surface soil temperature and negative bias in nighttime net irradiance reduced predictive efficiency. Error propagated from surface soil temperature probably contributes to the negative bias in net radiation. The reasonable predictive accuracy of PENFLUX for dry soil conditions demonstrates the feasibility of a numerically simplified model of soil‐residue energy exchanges, and justifies further evaluation against a range of residue architectures and environmental conditions.
Planting Dates for Early‐Maturing Soybean Cultivars
Authors: Steele Colleen C. , Grabau Larry J. 
Published: July 2010

AbstractEarly planting dates may not be required for successful culture of early‐maturing soybean [Glycine max (L.) Merr.] at midlatitudes in the USA. The objectives of this research were to evaluate early‐maturing soybean cultivars in southern environments, to try to identify cultivar characteristics contributing to the fit of these cultivars into this cropping system, and to determine the range of planting dates that best discriminate among northern cultivars. Field trials, involving 12 Maturity Group (MG) II cultivars, were planted in late April to mid‐May, late May to early June, mid‐June, and mid‐July on a Maury silt loam (fine, mixed, mesic Typic Paleudalf) near Lexington, KY, in 1993 and 1994. Yield response to planting date was consistent across years, showing best yields for mid‐June plantings. Pioneer 9273 produced significantly more grain than all other cultivars. Across years and planting dates, the lowest yielding cultivar (IA 2008) produced 19% less than did Pioneer 9273, emphasizing the importance of cultivar selection. Canopy closure ratings at reproductive growth stages R2 or R5 were somewhat better related to yield than were plant mass (at R2 or R5) or plant height. The shortest cultivars had the greatest stubble losses; producers may want to avoid such cultivars. Identification of high‐yielding cultivars was clearest for the first two planting dates. Perhaps cultivars that performed well under cool, moist soil conditions were favored by the earlier planting dates. Selection of early‐maturing cultivars for production south of their traditional full‐season areas appears to be best done from early planting dates in the southerly zone.
Evaluation of a Crop Simulation Model that Incorporates Gene Action
Authors: Hoogenboom Gerrit , White Jeffrey W. , Acosta‐Gallegos Jorge , Gaudiel Refe G. , Myers James R. , Silbernagel Matt J. 
Published: July 2010

AbstractCrop simulation models are receiving increasing use in agricultural research. However, applications to plant breeding have been limited, in part due to the restricted capabilities of models to represent genetic differences. A gene‐based simulation model, GeneGro, has been developed that integrates action of seven genes into a common bean (Phaseolus vulgaris L.) model. The genes for physiological traits identified in the model include Ppd, Hr, Fin, Fd, Ssz‐1, Ssz‐2, and Ssz‐3. Evaluation of GeneGro was performed by comparison of measured field data vs. simulated data, and through a sensitivity analysis of the model. The experimental data set for model comparison was comprised of 14 field trials conducted in Canada, the USA, Mexico, and Colombia, representing 213 treatment combinations and including 39 cultivars. GeneGro explained 75% of variation in days to flower, 68% in days to maturity, and 39% in seed mass, but only 11% of variation in seed yield. Most of the variation in simulated seed yield was accounted for by the model when mean effects of site and cultivars were removed through regression analysis. This suggests that the poor simulation of seed yield was partially due to errors in simulating differences among sites rather than from simulating the response of genotypes to sites. Seed yield simulations were made for 96 genotypes that represented all expected phenotypic combinations of the seven genes included in the model. Simulations were conducted using historical weather data from Fargo, ND; Madero, Mexico; and Palmira, Colombia. GeneGro predicted that photoperiod sensitivity, conferred by Ppd and Hr, would result in zero seed yields at Fargo, a slight seed yield increase at Madero, and no effect at Palmira. Testing effects of maturity on seed yield, the genotypes fin and Fd resulted in lower seed yields due to shorter growth cycles, in agreement with field trials. The predicted effects of the three genes related to seed size varied among the sites. These results support the use of genetic information to represent cultivar differences in simulation models. They also emphasize the need for a better understanding of the physiological genetics of traits such as phenology, seed size, and growth habit.
Species for Low‐Input Sustainable Turf in the U.S. Upper Midwest
Authors: Diesburg Kenneth L. , Christians Nick E. , Moore Richard , Branham Bruce , Danneberger T. Karl , Reicher Zachary J. , Voigt Thomas , Minner David D. , Newman Robert 
Published: July 2010

AbstractLow‐input sustainable turf (LIST) management represents a resource‐efficient option in maintaining uniform, persistent turf. What species are best suited to such management needs to be established. To this end, 12 hardy species were evaluated for 3 yr in Illinois, Indiana, Iowa, Michigan, Missouri, Ohio, and Wisconsin: crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schult. ‘Fairway’, ‘Ephraim’, and ‘Ruff’], streambank wheatgrass [Agropyron riparium Scribn. & Smith ‘Sodar’; syn. Elymus lanceolatus (Scribn. & J.G. Smith) Gould subsp. lanceolatus], Canada bluegrass (Poa compressa L. ‘Reubens’), hard fescue [Festuca ovina var. duriuscula (L.) Koch ‘Durar’; syn. F. lemanii T. Bastard], sheep fescue (F. ovina L. ‘Covar’ and common), tall fescue (F. arundinacea Schreb. ‘Alta’), bulbous bluegrass (P. bulbosa L.), alpine bluegrass (P. alpina L.), redtop (Agrostis alba L. ‘Reton’; Agrostis gigantea Roth), roughstalk bluegrass (P. trivialis L. ‘Colt’), colonial bentgrass (Agrostis tenuis Sibth. ‘Exeter’; syn. Agrostis capillaris L.), and buffalograss [Buchlöe dactyhides (Nutt.) Engelm. ‘Texoka’ and ‘NE‐315’]. AH were field‐established and compared at three mowing heights: 3.8 cm, 7.6 cm, and no mowing. Quality ratings were based on uniform persistence. Tall fescue and common sheep fescue were the best and most broadly adapted to LIST. In Iowa, hard fescue, Canada bluegrass, and crested wheatgrass also did well. Colonial bentgrass was best adapted in Missouri. Redtop and roughstalk bluegrass grew better in a north‐south area from Wisconsin through central Illinois to Missouri. The buffalograsses excelled in Ohio and southern Illinois. Over all species, the 7.6‐cm mowing height allowed the best turf quality. Specifically, tall fescue, colonial bentgrass, redtop, and common sheep fescue performed best at the 7.6‐cm mowing height. Covar sheep fescue, hard fescue, Canada bluegrass, and Fairway crested wheatgrass could not maintain persistent stands under the 3.8‐cm mowing height. No mowing resulted in intermediate levels of quality with all species. A 7.6‐cm mowing height would be appropriate for testing species in LIST within the seven‐state region used in this study.
Root Zone Temperature and Calcium Effects on Phosphorus, Sulfur, and Micronutrients in Winter Wheat Forage
Authors: Miyasaka Susan C. , Grunes David L. 
Published: July 2010

AbstractAn understanding of how environmental factors can alter accumulation of nutrients by plants is needed to anticipate and prevent mineral deficiencies in both plants and grazing animals. To determine the effects of root zone temperature (RZT) and Ca level on mineral concentrations of winter wheat (Triticum aestivum L.), ‘Centurk’ seedlings were grown under three RZT regimes (constant 8°C, constant 16°C, and transferral from 8°C after 23 d to 16°C) and four Ca levels (0.2, 0.6, 2.0, and 5.0 mM) in nutrient solution. Plants grown at 8°C RZT had significantly lower shoot and root concentrations and unit absorption rates of P, S, Cu, Zn, and Mn than did those grown at 16°C. Within 2 wk after transfer from 8°C to 16°C RZT, concentrations of P, S, Cu, Zn, and Mn in shoots and roots increased significantly. Increasing Ca levels in solution significantly increased shoot and root concentrations and unit absorption rates of P and Cu. In contrast, increasing Ca levels significantly decreased concentrations and unit absorption rates of Mn and Zn. Thus, a suboptimal RZT could depress accumulation of P, S, Cu, Zn, and Mn by winter wheat forage, and possibly induce mineral deficiencies in both plants and grazing animals. A high solution Ca level could partially ameliorate this adverse effect on P and Cu accumulation by wheat, but it also could exacerbate the problem of low Mn and Zn concentrations at a cool RZT.
Green Fallow for the Central Great Plains
Authors: Schlegel Alan J. , Havlin John L. 
Published: July 2010

AbstractUse of fallow to store soil water is a common practice in semiarid regions. In the central Great Plains, the most common dryland cropping system is winter wheat (Triticum aestivum L.)‐fallow. Stubble mulching involving tillage is the predominant weed‐control practice during the 14‐mo fallow period. As a result of tillage, soil organic matter content has declined 40 to 70% since the early 1900s. This decline has called for development of cropping practices that control soil erosion and increase soil organic matter. Green fallow is the practice of growing a legume during the time period not devoted to crop production. Water is a major limiting factor for crop production in the central Plains, and water use by the legume could reduce grain yields. Field studies were conducted near Tribune, KS, from 1990 to 1994 to evaluate green fallow in the central Great Plains. The objectives were to (i) evaluate the production potential of several dryland forage legumes, (ii) quantify the water use of dryland legumes as a function of growth period, and (iii) measure the effects of legume growth on grain yield of subsequent crops. Of 11 legume species evaluated, hairy vetch (Vicia villosa Roth) and yellow sweetclover (Melilotus officinalis Lam.) were the most promising in terms of biomass production and weed control. Hairy vetch was planted in a green fallow system and allowed to grow for selected periods of time. In all cases, green fallow depleted soil water and reduced grain yield of subsequent crops. Allowing hairy vetch growth throughout the fallow period reduced soil water by up to 178 mm and reduced grain yield by 42 to 83%. For every millimeter of soil water depletion by vetch, grain yields decreased by 15 kg ha−1. Although green fallow is too detrimental to subsequent crop yields to be recommended in the central Great Plains, dryland legumes may have potential as forage crops.
Fractal Analysis of Temporal Yield Variability of Crop Sequences: Implications for Site‐Specific Management
Authors: Eghball Bahman , Varvel Gary E. 
Published: July 2010

AbstractCharacterizing spatial and temporal variability is important in site‐specific or long‐term studies to evaluate the effects of different management systems on crop performance. Long‐term experiments offer unique possibilities to study the effects of management practices on crops and soils over time. The objective of this study was to characterize temporal grain yield variability of seven crop sequences using fractal analysis and to determine whether temporal or spatial variability dominated the grain yield variability. Three crops of corn (Zea mays L.), soybean [Glycine max (L.) Merr.], and sorghum [Sorghum bicolor (L.) Moench] were studied from 1975 to 1995 in various sequences. Semivariograms were estimated for the standardized crop yield. The slopes of the regression lines of log semivariogram vs. log lag (year) were used to estimate and compare fractal dimensions, which are indications of variability patterns. The intercepts of the log‐log lines, which indicate extent of yield variability, were also compared between crop sequences. A small D‐value indicates dominance of long‐term variation, while a large D‐value (near 2) indicates dominance of short‐term (year‐to‐year) variation. Corn had significantly less temporal yield variability than soybean or sorghum. Continuous corn had less yield variability than corn following soybean. Soybean had the greatest yield variability, regardless of crop sequence. Temporal variability was much more dominant than spatial variability in this study. Temporal variability may greatly influence how spatial variability is expressed in a given field. Yield maps, which are used as an indication of past management in site‐specific cases, may not be useful in making future management decisions when temporal variability is great. In a less productive year, spatial variability of any nutrient may not make much difference in crop yield of a given field.
Zinc and Cadmium Effects on the Early Stages of Nodulation in White Clover
Authors: El‐Kenawy Z. A. , Angle J. Scott , Gewaily E. M. , El‐Wafai N. A. , van Berkum P. , Chaney Rufus L. , Ibekwe M. A. 
Published: July 2010

AbstractAddition of heavy metals to soils from sources such as biosolid application, smelter emissions, fertilizers, and the like may produce soil solution concentrations of Zn and Cd that can potentially restrict nodulation of legume crops such as white clover. To assess the effects of Zn and Cd on the early stages of nodulation of white clover, a solution culture study was conducted. Rhizobia [Rhizobium leguminosarum bv. trifolii] of a metal‐sensitive strain (USDA 2063) and a metal‐tolerant strain (USDA 2046) were inoculated into nutrient solution with white clover seedlings containing EGTA to buffer Zn2+ and Cd2+ activities. The calculated activities of Zn2+ were p = 8.00, 5.70, 5.25, and 5.00; the calculated activities of Cd2+ were p = 10.50, 9.50, 8.75, and 8.50. Phase‐contrast microscopy was used after staining roots with methylene blue to observe root hair infection at intervals of 1, 12, 24, 72, and 168 h. Few differences were observed between the sensitive and tolerant rhizobial strains. At the lowest Zn concentration, initial attachment of bacteria to root hairs was observed within 1 h. At the highest Zn concentration, attachment was not observed until 12 h. Also, at the highest Zn concentration, a delay was observed for up to 60 h and 4 d, respectively, for the first signs of root hair curling and infection thread formation. Shoot weight decreased with increasing Zn concentration. Few Cd‐induced effects on early stages of nodule development were observed. Cadmium was more toxic to plant growth than Zn. These results show that in addition to direct effects on the macro and microsymbiont, the process of nodulation is susceptible to the toxic effects of heavy metals.
Integrated Weed Management Using Narrow Corn Row Spacing, Herbicides, and Cultivation
Authors: Johnson Gregg A. , Hoverstad Thomas R. , Greenwald Rene E. 
Published: July 2010

AbstractPotential increases in corn (Zea mays L.) grain yield have led many producers to consider using narrow corn rows. Narrow row spacing is also thought to play a role in reducing weed interference through enhanced light interception by the crop. However, there is little information on how narrow row spacing and cultivation fit into an integrated weed and crop management strategy. The objective of this research was to investigate the potential for reduced herbicide amount (either through below‐label rate and/or banded applications) using narrow corn crop row spacing and timely cultivation. Field studies were conducted in 1995 and 1996 at the University of Minnesota Southern Experiment Station in Waseca. Corn was planted in 51‐ and 76‐cm row spacings. Within each row‐spacing treatment, plots were either cultivated or not cultivated. Eight herbicide treatments were applied to each row space and cultivation plot. Corn row spacing had little impact on giant foxtail (Setaria faberi Herrm.) and common ragweed (Ambrosia artemisiifolia L.) visual control, density, biomass, or height. Cultivation was the single most important variable in reducing the amount of herbicide used. Grain yield was not increased by planting corn in narrow rows. Increased grain yield and weed control reported in previous research studies using narrow row spacing may be due to the choice of hybrid, plant population, and weed spectrum present.