bluuebunny/crossref_metadata_2025_split huggingface dataset:
Use of a Chlorophyll Meter at the Early Dent Stage of Corn to Evaluate Nitrogen Sufficiency
Authors: Piekielek William P. , Fox Richard H. , Toth John D. , Macneal Kirsten E. 
Published: July 2010

AbstractA late‐season chlorophyll meter test for corn (Zea mays L.) could provide growers with a convenient evaluation of that year's N management program, along with information useful for N fertilizer rate decisions in subsequent growing seasons. Chlorophyll meter (SPAD 502) readings were taken late in the growing season on corn ear leaves in replicated plots of 357 N treatments from 93 N‐response experiments conducted in Pennsylvania. At sites not affected by severe late‐season drought or disease, chlorophyll meter readings taken at the 1/4 milk line stage separated N‐deficient from N‐sufficient treatments with 93% accuracy using a critical level of 52.0 SPAD units. If meter readings were normalized at each site by comparison with a site‐specific high‐N reference reading, chlorophyll meter readings of ear leaves made from the late milk to the middent stage of corn could separate N‐deficient from N‐sufficient treatments with 92% accuracy using a relative SPAD reading critical level of 0.93. For treatments with meter readings below the critical level, relative grain yields and the additional N that would have been needed for economic optimum grain yield were correlated with chlorophyll meter test values. For treatments with a meter reading above 52.0 SPAD units, the amount of excess N that may have been applied could not be accurately predicted. For corn tested at the 1/4 milk line stage, we suggest an N‐sufficiency range of 52.0 to 56.0 SPAD units, above which there is a 70% probability of an excess of >50 kg N ha−1 having been applied.
Estimation of Leaf Area Index for Cotton Canopies Using the LI‐COR LAI‐2000 Plant Canopy Analyzer
Authors: Hicks Stanley K. , Lascano Robert J. 
Published: July 2010

AbstractMeasurement of leaf area index (LAI) is useful for understanding cotton (Gossypium hirsutum L.) growth, water use, and canopy light interception. Destructive measurement is time consuming and labor intensive. Our objective was to evaluate sampling procedures using the Li‐Cor (Lincoln, NE) LAI 2000 plant canopy analyzer (PCA) for nondestructive estimation of cotton LAI on the southern High Plains of Texas. We evaluated shading as a way to allow PCA measurements in direct sunlight and the influence of solar direction when using this procedure. We also evaluated a test of canopy homogeneity (information required for setting PCA field of view), determined the number of belowcanopy measurements required, examined the influence of leaf wilting on PCA LAI determinations, and tested an alternative method (masking the sensor's two outer rings) for calculating LAI from PCA measurements. The best agreement between PCA and destructively measured LAI values was obtained when PCA observations were made either during uniformly overcast conditions or around solar noon using the shading method. Heterogeneous canopies with large gaps between rows required both a restricted (45°) azimuthal field of view and averaging the LAI values for two transects, made with the field of view parallel and then perpendicular to the row direction. This method agreed well (r2 = 0.84) with destructively measured LAI in the range of 0.5 to 3.5 and did not deviate from a 1:1 relationship. The PCA underestimated LAI by ≥ 20% when measurements were made on canopies wilted due to water stress. Masking the PCA sensor's outer rings did not improve the relationship between estimated and measured LAI in the range of LAI sampled.
Effect of Nitrogen Supply on Maize Yield: II. Field and Model Analysis
Authors: Muchow Russell C. , Sinclair Thomas R. 
Published: July 2010

AbstractExperiments investigating the yield response of maize (Zea mays L.) to applications of fertilizer N are generally analyzed empirically. While the nature of the yield response can be characterized, information on the effects of various components influencing the soil and crop N budgets are unresolved. The objective of this study was to examine the results of a series of N fertility experiments with the aid of a mechanistically based crop model. The experiments resulted in grain yields ranging from 99 to 1102 g m−2, and these yields were well simulated by the model (r2 = 0.97). Under high fertility conditions, temperature and solar radiation interception explained the variation in yield among environments. Under low fertility conditions, mineralization of soil organic N was especially important in explaining yield variations among environments. Management practices preceding the experimental crops were hypothesized to have large effects on the N availability in the soil, and consequently influence observed and simulated yields. Sensitivity tests confirmed the importance of defining the initial soil organic N levels in simulating crop growth and yield when there is little or no applied N fertilizer.
Degradation by Ficin of Protein from Alfalfa Hay Conserved as Conventional and Laboratory‐Scale Bales
Authors: Coblentz Wayne K. , Fritz John O. , Bolsen Keith K. , Skinner Daniel Z. , Cochran Robert C. 
Published: July 2010

AbstractFicin was utilized in a 2‐h in vitro incubation procedure to characterize the partitioning of N into fractions based on resistance of alfalfa (Medicago sativa L.) proteins to enzymatic degradation. Objectives included evaluation of the following treatment effects on N partitioning: (i) moisture content; (ii) laboratory bale density; (iii) laboratory baling without heating during storage; (iv) spontaneous heating in laboratory bales; and (v) conventional baling. Alfalfa at three moisture levels (268, 229, and 185 g kg−1) was conserved in the following bale types: (i) conventional bales; (ii) laboratory bales made at 1.0, 1.3, 1.7, and 2.0 times the density of conventional bales and incubated in two environments (straw stacks or insulated boxes); or (iii) a prestorage control. Significant (P ≤ 0.05) moisture ✕ bale type interactions were observed for most N fractions, indicating N partitioning among bale types was greatly changed in high‐moisture hay, but remained relatively stable in dry hay. Except for the Pool‐C N fraction, which includes Maillard reaction products, laboratory‐bale density generally had little effect on N partitioning. At the medium and low moisture levels, prestorage controls had more Pool‐A N (greater buffer solubility) than did nonheated laboratory bales. Heating in laboratory bales facilitated additional significant change in N fractions, relative to nonheated laboratory bales. While Maillard reaction products increased in response to laboratory bale density, large increases in the portion of potentially available N most resistant to enzymatic degradation (B2 subfraction), appeared dependent on large heat increments incurred specifically in conventional bales.
Maize Nodal Root Response to Soil Ridging and Three Tillage Systems
Authors: Thomas Andrew L. , Kaspar Thomas C. 
Published: July 2010

AbstractA greater understanding of maize (Zea mays L.) nodal root response to soil ridging and tillage systems is needed to maximize the benefits of ridge‐till and other conservation tillage systems. Field (1992 and 1993 near Marshalltown, IA) and greenhouse (two studies with two trials each) experiments were conducted to examine the effect of soil ridging, height of ridging, and three tillage systems (no‐till, ridge‐till, and chisel‐plow) on the number and stem node position of maize nodal roots and on internode length. Field plants were ridged during cultivation. In the greenhouse, ridging was simulated by using polyvinyl chloride rings to hold soil around the base of plants. Numbers of nodal roots, numbers of nodes developing functional roots, internode lengths, shoot dry weights, and grain yields (field study) were determined. In one greenhouse experiment, unridged plants developed an average of 38.4 functional nodal roots, while ridged plants developed 50.0, an increase of 30%. In the same greenhouse experiment, ridging significantly increased lengths of Internodes 6 and 7, which were covered with soil during ridging. Average length of Internode 7 increased from 64 mm to 101 mm with ridging. Increasing ridge height increased internode length and number of nodal roots in the controlled greenhouse experiments, but not in the field. In field experiments, ridge‐till caused development of significantly more functional nodal roots as compared with no‐till (1992 and 1993) and chisel‐plow (1992). Plants from no‐tiil developed 53.1 and 46.0 functional nodal roots in 1992 and 1993, respectively, while plants from ridgetill developed 58.7 and 49.1 roots. Shoot dry weight and grain yield were not affected by ridging or tillage treatments in the greenhouse or field.
Crop Sequence Effects on Response of Corn and Soil Inorganic Nitrogen to Fertilizer and Manure Nitrogen
Authors: Lory John A. , Randall Gyles W. , Russelle Michael P. 
Published: July 2010

AbstractFertilizer N and manure frequently are applied to corn (Zea mays L.) grown after alfalfa (Medicago sativa L.) at rates similar to those applied to continuous corn, although corn following alfalfa typically requires little additional N to attain maximum dry matter. Consequently, similar amounts of applied N may affect soil NO3 differently in rotational than in continuous corn. There is little information evaluating crop sequence effects on residual soil NO3 derived from fertilizer N and manure. In two 2‐yr experiments at two locations in Minnesota, we evaluated the effect of crop sequence on response of corn grain dry matter, grain N, and stover N, and of soil inorganic N (NO3‐N and NH4‐N) to fertilizer N and dairy manure. Grain dry matter of first‐year corn following alfalfa did not respond to applied N at Rosemount and typically was less responsive than continuous corn at Waseca. Crop sequence effects on soil NO3 response to manure and fertilizer N were similar. Preplant fertilizer N application of 157 kg ha−1 increased residual soil NO3‐N the following spring an average of 45 kg ha−1 more in first‐year corn following alfalfa than in continuous corn, except when excessive precipitation caused apparent high losses of applied N. Grain N content and soil NO3 responded similarly to fertilizer N in both second‐year corn following alfalfa and continuous corn. Efforts to reduce the buildup and potential loss of soil NO3 in the corn portion of alfalfa‐corn rotations should focus on reducing N application to first‐year corn following alfalfa. These N applications have little agronomic value and can dramatically increase residual soil NO3.
Assessing Cultivar Adaptability by Multiple Comparison with the Best
Authors: Piepho Hans‐Peter 
Published: July 2010

AbstractRegional yield trials are conducted to identify cultivars that are well adapted to specific environments. This note proposes application of a multiple comparison procedure for assessing cultivar adaptability. A cultivar is regarded as adapted if it does not differ from the best by more than some prespecifled amount. The procedure assigns cultivars to one of three groups: (i) adapted; (ii) unadapted; and (iii) unclassified. The classification is based on simultaneous confidence intervals for the difference between all cultivars and the best cultivar. Such classification may be a useful tool for cultivar recommendations.
Fluridone Reveals Root Elongation Differences among Alfalfa Germplasms
Authors: Meyers Lynda L. , Russelle Michael P. , Lamb JoAnn F. S. 
Published: July 2010

AbstractAlfalfa (Medicago sativa L.) is a deep‐rooted perennial that may be able to remove nitrate from subsoil beneath the rooting zone of annual crops. Alfalfa cultivars with rapid and deep root elongation would be beneficial for reducing future nitrate contamination of ground water supplies. The objectives of this research were to (i) develop a protocol using the herbicide fluridone {1‐methyl‐3‐phenyl‐5‐[3‐(trifluromethyl) penyl]‐4(1H)‐pyridinone} as a marker for indicating alfalfa root penetration in soil, and (ii) determine the variability in rate of geotropic root elongation within and among diverse alfalfa germplasms. Fluridone caused rapid, distinctive bleaching of alfalfa leaves at a rate of 25 mg a.i. kg−1 soil, without being fatal. When transplanted after onset of fluridone symptoms, alfalfa recovered and resumed normal growth and flowering. Alfalfa populations did not differ in sensitivity to fluridone. Decomposition of roots from a fluridone‐treated plant did not cause symptom development in other plants. Individual plants within alfalfa germplasms differed by 56 d in onset of symptoms, indicating a similar difference in root activity at 80 cm depth in soil. Mean geotropic root elongation rate for 12 diverse germplasms ranged from 1.12 to 1.40 cm d−1. Populations selected for unique root morphological traits were significantly faster in geotropic root elongation rate than their nonselected parental populations. Our method permits in situ identification of plants with rapid geotropic root elongation rates within heterogeneous populations and has proven useful in germplasm selection.
Cropping Systems for Perennial Ryegrass Seed Production: I. Minimum Tillage Establishment of Rotation Crops in Stubble Without Burning
Authors: Young William C. , Youngberg Harold W. 
Published: July 2010

AbstractViability of alternative crops in a monoculture grass seed cropping system will be enhanced if minimum tillage establishment through grass seed stubble is successful without burning. Our objective was to compare agronomic performances of red clover (Trifolium pratense L.), white clover (T. repens L.), meadowfoam (Limnanthes alba L.), and pea (Pisum sativum L.) when drill‐seeded in the stubble of a third‐year perennial ryegrass (Lolium perenne L.) seed crop, with and without burning stubble. Four field experiments were conducted during a 6‐yr period on a Woodburn silt‐loam (fine‐silty, mixed, mesic Aquultic Argixerolls) soil in western Oregon. Ryegrass stubble was either propane‐burned or was not burned before drill‐seeding the rotational crops. In one experiment, a rotary strip‐till drill was also compared with a no‐till drill for establishing white clover in perennial ryegrass stubble. Burning the stubble enhanced spring growth of red clover; however, forage and seed yields in the first crop year were 47 and 66% higher, respectively, for the nonburned than the burned treatments. There were no differences among treatments for forage and seed yields of red clover in the second crop year. Treatments did not affect dry matter or seed production of white clover and spring pea. Meadowfoam forage and seed yields were 26 and 24% lower, respectively, for the nonburned than the burned treatments. We concluded that burning stubble before seeding may be advantageous for winter annual seed crops that mature during the spring or early summer months. However, burning stubble is not beneficial, or may be disadvantageous, for crops that mature during the late summer in areas such as Oregon with a Mediterranean climate. The no‐till drill was superior to the strip‐till drill for establishing white clover in perennial ryegrass stubble regardless of stubble management method.
Seeding Rate Effects on Rough Rice Yield, Head Rice, and Total Milled Rice
Authors: Gravois Kenneth A. , Helms Ronnie S. 
Published: July 2010

AbstractWithout an adequate and uniform rice (Oryza sativa L.) stand, optimum rough rice yields are difficult to attain. Most seeding rate research has emphasized optimizing rough rice yields, with little consideration given to the effect of seeding rate on head rice (percentage of whole milled kernels) and total milled rice (percentage of whole milled kernels plus milled broken kernels). Thus, our objective was to assess the effect of seeding rate on head rice and total milled rice of two very early‐season rice cultivars (Millie and Adair) and two midseason rice cultivars (Katy and Kaybonnet). The experiment was conducted at the Pine Tree Experiment Station near Colt, AR, during 1992 and 1993. The cultivar (maturity group) × seeding rate interaction was significant for head rice and total milled rice, suggesting that, for head rice and total milled rice, the four cultivars responded differently to seeding rate. There was a linear decrease in head rice as seeding rate decreased for Millie, a quadratic decrease in head rice as seeding rate decreased for Adair, and a linear increase in head rice as seeding rate decreased for both Katy and Kaybonnet. We surmise that increased tillering and decreased kernel weights at the lower seeding rates decreased the head rice for Adair and Millie. Total milled rice decreased linearly with decreasing seeding rate only for Adair. When evaluating thin rice stands for potential performance or replanting, both cultivar and head rice and total milled rice losses should be considered.
A Dual‐Heater Gauge for Measuring Sap Flow with an Improved Heat‐Balance Method
Authors: Peressotti Alessandro , Ham Jay M. 
Published: July 2010

abstractMeasurements of sap flow in intact plant stems help quantify biophysical relationships governing water transport in the soil‐crop‐atmosphere continuum. Research was conducted to develop and test a dual‐heater sap flow gauge based on an improved heat‐balance theory. The dualheater gauge contains two resistance heaters that, when operated in variable power mode, allow mathematical manipulation of the heat balances, so no empirical calibration or zero set is necessary (i.e., no gauge factor). Prototype dual‐heater gauges were fabricated and tested on containergrown corn (Zea mays L.) with stem diameters between 25 and 30 mm. Traditional single‐heater heat‐balance gauges were also built and tested to compare the two designs. Gauges were tested simultaneously in a greenhouse over a continuous 5‐d drying cycle when flows ranged from 0 to 140 g h−1 and daily water use ranged from 137 to 1064 g d−1. Both gauge types measured hourly sap flow to within ± 10% relative to gravimetric estimates of transpiration. The dual‐ and single‐heater gauges measured cumulative sap flow over the 5‐d test period to within 4.0 and 9.5%, respectively. The largest errors in daily sap flow, 34%, occurred in the single‐heater gauge when the plants were subjected to water stress. The dual‐heater approach could measure sap flow without predetermined or empirically derived calibration factors or zero sets. Accurate measurements of sap flow were obtained 15 min after the gauge was attached to the plant stem. Additionally, the dual‐heater gauge was easier to build, consumed less power, and caused less stem heating than the single‐heater gauge.
MODWht3: A Development‐Driven Wheat Growth Simulation
Authors: Rickman Ronald W. , Waldman Sue E. , Klepper Betty 
Published: July 2010

AbstractCrop growth simulations are needed to help organize our knowledge of plant response to the environment for the purpose of assisting growers in management decisions, predicting impacts of land use decisions, and predicting the consequences of probable climatic variation. This paper describes the derivation, combination, and (where necessary) calibration of the models required to produce a simulation of the seasonal development and growth of winter wheat. The simulation provides appearance time and size estimates for each aboveground plant part (leaves, stems, spikes, and kernels), length and mass of roots with depth, time of occurrence of phenological events (germination, emergence, tillering, single ridge, double ridge, jointing, boot, heading, anthesis, soft dough, mature, and harvest ripe), rate and amount of water evaporated and transpired, uptake of N from the soil profile, and estimates of daily net photosynthesis. Strengths of the simulation include that it predicts dates for all crop phenological stages, it estimates sizes for all plant parts on a daily basis for comparisons with almost any observed field data, it is organized according to the natural structure of the system being simulated, and it is designed to be changed. Weaknesses include current lack of ranges for parameter values for different cultivars, a simplistic soil water budget, and limitations in specifying nutrient distribution among plant organs. No weed, pathogen, or insect models are incorporated; however, the program that implements the simulation is specifically designed to be easily modified, so pest models could be added.
Row Spacing Effects on Light Extinction Coefficients of Corn, Sorghum, Soybean, and Sunflower
Authors: Flénet Francis , Kiniry James R. , Board James E. , Westgate Mark E. , Reicosky Donald C. 
Published: July 2010

AbstractIn many crop models, light intercepted by a canopy (IPAR) is calculated from a Beer's Law equation: IPAR = PAR × [1 − exp(−k × LAI)], where k is the extinction coefficient, PAR the photosynthetically active radiation, and LAI the leaf area index. The first objective of this study was to investigate the effect of row spacing on k for corn (Zea mays L.), sorghum [Sorghum bicolor (L.) Moench], soybean [Glycine max (L.) Merr.], and sunflower (Helianthus annuus L.) to provide information for modeling. Data from literature and from an experiment conducted at Temple, TX, were evaluated. The second objective was to investigate effects of time of day and stage of crop development on k for different row spacings. Seeds of all four species were sown in rows 0.35, 0.66, or 1.00 m apart. Measurements of canopy light interception were taken near solar noon on two dates before anthesis. At anthesis, extinction coefficients were determined at 0845, 1015, and 1145 h (solar time). The extinction coefficient showed a linear decrease as row spacing increased. For each crop, the effect of row spacing on k was described by one linear regression for most data. Stage of crop development and stage of development × row spacing interaction did not significantly affect k during the period of measurements. The effect of time of day was significant for all four crops, and the time of day × row spacing interaction was significant for soybean and sunflower. Thus, modeling light interception for different row spacings should account for these effects.