bluuebunny/crossref_metadata_2025 huggingface dataset:
Response of Cotton to Varying COz, Irrigation, and Nitrogen: Yield and Growth
Authors: Kimball B. A. , Mauney J. R.
Published: July 2010

The CO2 concentration of the atmosphere is increasing and is expected to double sometime near the middle of the next century. To determine the effects of such a CO2 increase on cotton (Gossypium hirsutum L.) growth and productivity, a series of experiments from 1983 through 1987 were conducted with open‐top CO2‐enriched field chambers at ample as well as limiting levels of water and N at Phoenix, AZ. Comparisons with open‐field plots showed that there was a significant chamber effect, amounting to a 30% average increase in growth inside, but under dry conditions in 1985, the situation was reversed. No significant effects of CO2 on harvest index, root‐shoot ratio, or lint percentage were found, so the primary effect of elevated CO2 was to produce plants that were larger. Comparing the results of 500 and 650 µmol mol−1 CO2 treatments, the increments of growth from ambient (about 350 µmol mol −1) to 500 µmol mol−1 were not significantly different from increments from 500 to 650 µmol mol−1. No statistically significant interactions were detected between CO2 level and either irrigation or nitrogen level, even when these variables were sufficiently low enough to limit growth. However, under well‐maintained water stress conditions, the growth response to CO2 tended to he somewhat larger than under normal irrigation levels. Averaging over all the data available from these experiments, seed cotton yield (lint plus seed) and above‐ground biomass were increased by 60 and 63%, respectively, by CO2 enrichmen to 650 µmol mo1−1.
Carbohydrates in Alfalfa Seed Developed for Salt Tolerance during Germination
Authors: Dobrenz A. K. , Smith S. E. , Poteet D. , Miller William B.
Published: July 2010

Alfalfa (Medicago sativa L.) is an important forage crop in many areas of the world where salinity limits crop productivity. Alfalfa that is salt tolerant during the germination stage has been developed through eight cycles of recurrent selection starting with Mesa‐Sirsa. We investigated physiological attributes that may have been affected by selection, recognizing that understanding the basis of tolerance could facilitate more precise techniques for identifying salt‐tolerant plants in breeding programs. Free sugars in seed of Mesa‐Sirsa and in Cycle 5 and Cycle 8 (C5 and C8) from the selection program were extracted with 95% (v/v) ethanol and the residue hydrolyzed with 4 M H2SO4. All carbohydrates were quantified by HPLC. Percent galactomannan, glucose, and arabinose in the acid hydrolysate were not significantly different in Mesa‐Sirsa, C5, and C8 seeds. Percent stachyose and glucose were not different in the free sugar extraction of the seed; however, raffinose and sucrose were significantly higher in C8 seed. The increase in these free sugars was not sufficient to explain the increased salt tolerance of the selected populations.
Differentiating Chloride Susceptibility in Soybean Cultivars
Authors: Yang J. , Blanchar R. W.
Published: July 2010

Fertilization with KCl can induce a Cl toxicity that decreases the yield of soybean [Glycine max (L.) Merr.]. The objective of this study was to see if Cl toxicity can be avoided by selecting cultivars that take up less Cl from the soil. Sixty soybean cultivars, 12 each from Maturity Groups II, III, IV, V, and VI were grown on a Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf) without added Cl or with 673 kg Cl ha−1 added as CaCl2. The addition of Cl increased the mean Cl concentration of all cultivars from 1.5 to 18.8 g Cl kg−1 at 15 d and from 0.4 to 1.3 g Cl kg−1 at 80 d. All 36 cultivars from MG II, III, and IV, along with 5 cultivars from MG V and VI, bad significantly higher concentrations of Cl in leaves than did 19 cultivars from MG V and VI. Cultivars with high Cl concentrations were referred to as accumulators and those with low concentrations as excluders. The occurrence of leaf scorch, a symptom of Cl toxicity, in Cl accumulator cultivars was significantly higher than in Cl excluder cultivars. Leaf scorch ratings were positively correlated with Cl concentrations of soybean leaves at 15 and 80 d. Chloride concentrations in the leaves were higher (accumulators, 24.3 g kg−1; excluders, 7.0 g kg−1) at the early growth stages than in the later stages (accumulators, 1.8 g kg−1; excluders, 0.3 g kg−1). Addition of CaCl2 increased Cl concentrations in seeds of Essex, an accumulator cultivar, but had no significant effect on oil and protein content. The average grain yields of Cl accumulator cultivars were significantly decreased by 16% due to Cl addition, while grain yields of excluder cultivars were not significantly reduced. Cultivar selection in MG V and VI may be a means of minimizing Cl effects associated with muriate of potash fertilization.
Response of Spikelet Number to Plant Nitrogen Concentration and Dry Weight in Paddy Rice
Authors: Hasegawa Toshihiro , Koroda Yasuo , Seligman No'am G. , Horie Takeshi
Published: July 2010

Spikelet density, defined as number of spikelets per unit area of crop, is a major determinant of paddy rice (Oryza sativa L.) yield. Nitrogen accumulation at the panicle formation stage is closely associated with spikelet density, but regional variation has been observed in this relationship. Elucidating the reason for this interregional variation will improve our understanding of spikelet density response to N nutrition. A number of functions were tested to identify an appropriate relationship between N accumulation at the panicle formation stage and spikelet number in japonica rice. The data were collected from 157 field experiments conducted in widely different regions in Japan. The correlation with total N accumulated at the panicle formation stage was significant, but relatively low (r2 = 0.64). A considerably larger part of variation (r2 = 0.84) could be accounted for by a model based on a linear function of plant N concentration and an asymptotic function of aboveground biomass at the panicle formation stage. The standard error of the estimate was 3309 spikelets m−2 for the set of data that ranged from 10 500 to 46 400 spikelets m−2. This model can serve to give a fair estimate of potential grain number in japonica rice. The two distinct responses indicated that vigorous biomass growth with heavy dilution of plant N concentration up to the panicle formation stage could result in inefficient use of N for spikelet formation.
Intercrop Performance of Pearl Millet, Amaranth, Cowpea, Soybean, and Guar in Response to Planting Pattern and Nitrogen Fertilization
Authors: Clark Kerry M. , Myers Robert L.
Published: July 2010

Intercropping is a common practice in developing countries because it may produce higher total yields than monocropping. The objective of this study was to apply intercropping principles to alternative and traditional crops in the USA under mechanized conditions. Although these crops have been examined in intercropping systems, in most cases studies were not conducted with improved varieties found in the USA or in strip widths that can accommodate machinery. A field study was conducted at two central Missouri locations in 1991 and 1992 to determine the effect of intercropping on grain yields of pearl millet [Pennisetum glaucum (L.) R. Br.], amaranth (Amaranthus hypochondriacus L. × A. hybridus L.), cowpea [Vigna unguiculata (L.) Walp.], guar [Cyamopsis tetragonoloba (L.) Taub.], and soybean [Glycine max (L.) Merrill]. Treatments were assigned in an incomplete factorial design and consisted of planting pattern (monocrops, narrow and wide row strips, and alternate row intercrops), N fertilizer (0, 56, or 112 kg N ha−1), and component crop combination. Each intercrop consisted of a legume (cowpea, soybean, or guar) and a nonlegume (pearl millet or amaranth). In the strip intercrops, only cowpea showed a consistent yield response to planting pattern, with the narrow strip arrangement with amaranth yielding 53 and 39% lower than its monocrop in two environments. Land equivalent ratios of amaranth and pearl millet grown in alternate rows with cowpea were not significantly different from their monocrops. At the Columbia site, yields of alternate row intercrops generally did not increase upon addition of N and in 1992, amaranth yield at 0 kg N ha−1 was 25% higher in the alternate row intercrop than it was at the same N rate in the monocrop. In general, grain yields were similar in the various intercrops compared with monocrops.
Nitrogen Utilization of Selected Cropping Systems in the U.S. Northeast: I. Dry Matter Yield, N Uptake, Apparent N Recovery, and N Use Efficiency
Authors: Guillard Karl , Griffin Gary F. , Allinson Derek W. , Rafey M. Moosa , Yamartino William R. , Pietrzyk Stephen W.
Published: July 2010

Excessive application of N‐containing fertilizers may result in high concentrations of soil nitrate. Soil nitrate levels can be reduced with cropping systems that best utilize N. Split‐plot design experiments were conducted in Connecticut from 1987 through 1990 on a Paxton fine sandy loam soil (coarse‐loamy, mixed, mesic Typic Dystrochrept) to determine the effectiveness of various cropping systems in utilizing N. Orchardgrass (Dactylis glomerata L.), red clover (Trifolium pratense L.), a doublecrop system of oat (Avena sativa L.) followed by the forage brassica tyfon [Brassica rapa L. × B. pekinensis (Lour.) Rupr.], and maize (Zea mays L.) followed by a cover crop of winter rye (Secale cereale L.) received preplant N at 0, 112, 224, 336, and 448 kg ha−1. Cropping systems were tested three times for two consecutive growing seasons, with N applied only in the first season. Dry matter yield (DMY), N uptake (NUP), apparent N recovery (NREC), and N use efficiency (NUE) were determined. Maize‐rye produced the greatest DMY (18.3 to 22.8 Mg ha−1), followed by oat‐tyfon (9.8 to 16.5 Mg ha−1). Highest NUP (121 to 329 kg N ha−1) and NREC (46.5 to 81.7%) were obtained by oat‐tyfon. The greatest NUE was produced by maize‐rye and oat‐tyfon at 112 kg N ha−1. The oat‐tyfon double crop provides the most effective means for preventing N loss among the systems evaluated for N rates > 112 kg ha−1.
Regrowth of Bromegrass Species, a Bromegrass Interspecific Hybrid, and Meadow Foxtail in a Short‐Season Environment
Authors: Van Esbroeck George A. , Baron Vern S. , King Jane R.
Published: July 2010

Regrowth in pastures is critical to economic production in short‐season areas. This study compared regrowth characteristics among three Bromus genotypes and meadow foxtail (Alopecurus pratensis L.) during late summer and fall. Growth analyses were conducted and yield components were determined in ‘Carlton’ smooth bromegrass (B. inermis Leyss.), ‘Regar’ meadow bromegrass (B. riparius Rhem.), an experimental strain (S9044) derived from F2 plants of a smooth ✕ meadow bromegrass cross, and common meadow foxtail. Seven weeks of plant regrowth after severe defoliation were characterized during 1985 and 1986 at Lacombe, AB, Canada (52° 28' N lat). The variation among the three grass species and the interspecific hybrid that was most critical to regrowth yield occurred during the first 21 to 28 d after defoliation. Smooth bromegrass consistently yielded less dry matter (DM) and had lower crop growth rates (CGR) than the other genotypes. Smooth bromegrass seemed limited most by a slowly developing leaf area index (LAI) as a result of a low and slowly developing tiller density. S9044 was improved over smooth bromegrass for regrowth yield and traits related to rapid regrowth. S9044 approached equilibrium tiller density quickly and had a large leaf area per tiller, which resulted in a higher leaf area expansion rate than in smooth bromegrass. Meadow bromegrass had CGR and DM yield similar to S9044, but the average LAI for meadow bromegrass was only 71% of that for S9044. Meadow bromegrass compensated for a small LAI with a specific leaf weight that was 1.4‐fold higher than S9044. When soil water was adequate, meadow foxtail produced regrowth equal to S9044 and meadow bromegrass through rapid development of leaf area of moderate specific leaf weight and a relatively large tiller size, given a high tiller density. As exhibited by meadow bromegrass, high specific leaf weight combined with rapid tiller development are traits associated with regrowth yield that may be worth exploiting in developing germplasm for short‐season areas where small LAI may be the norm.
Mean Squared Error of Yield Prediction by SOYGRO
Authors: Colson Josianne , Wallach Daniel , Bouniols Andrée , Denis Jean‐Baptiste , Jones James W.
Published: July 2010

Yield prediction is often one of the major intended uses of a crop simulation model. It is therefore important to evaluate how well a model performs as a predictor. The purpose of this study was to evaluate and analyze how well the SOYGRO model predicts soybean yield, using as a criterion the mean squared error of prediction (MSEP). The four target populations for prediction were irrigated or unirrigated plots at one location in France, for each of two varieties. The model parameters are estimated from the irrigated plots. The estimated MSEP values are on the order of 1(t ha−1)2 for all the target populations. For comparison, we defined an AVERAGE model. This model uses the average observed irrigated yield for each cultivar as the predictor of unobserved yields. AVERAGE was a better predictor than SOYGRO for the irrigated populations, while SOYGRO was better for the unirrigated populations. It seems that SOYGRO has sufficient built‐in biological realism to extrapolate more reasonably than the AVERAGE model from irrigated to unirrigated conditions; however, SOYGRO does not make as effective use of the data used for parameter estimation as does AVERAGE.
Economics of Growing Verticillium Wilt‐Resistant and Adapted Alfalfa Cultivars in Western Canada
Authors: Smith Elwin G. , Acharya Surya N. , Huang Henry C.
Published: July 2010

Alfalfa (Medicago sativa L.) production with cultivars susceptible to verticillium wilt (VW) (caused by Verticillium albo‐atrum Reinke & Berthier) or those poorly adapted to the region causes significant losses in forage productivity in western Canada. This study estimated the economic benefits that could be obtained by growing VW‐resistant and adapted cultivars in this region. The analysis used irrigated forage yield data from a 7‐yr trial conducted near Lethbridge, AB. The yearly benefit of high resistance to VW over moderately high resistance was $21 ha−1 and over low resistance was $44 ha−1. The potential yearly benefits to producers in western Canada from the development and adoption of high VW‐resistant cultivars were estimated at $2.2 million. The local benefits of growing adapted cultivars on irrigated land were $22 ha−1 yr−1. The regional benefits to western Canada from using adapted cultivars were $26.6 million yr−1. The greater potential benefit from growing adapted cultivars was attributed to benefits applied to all areas of western Canada, whereas benefits from VW applied to areas infested with VW.
Spectral Properties of Leaves Deficient in Iron, Sulfur, Magnesium, and Manganese
Authors: Masoni Alessandro , Ercoli Laura , Mariotti Marco
Published: July 2010

In crop plants, deficiency of an essential element may drastically reduce growth rate and yield. Research on the use of leaf spectral properties in the detection of crop mineral deficiency is needed. The objective of this study was to examine the effects of Fe, S, Mg, and Mn deficiency on reflectance (R), absorptance (A), and transmittance (T) spectra of barley (Hordeum vulgare L.), wheat (Triticum aestivum L.), corn (Zea mays L.), and sunflower (Helianthus annuus L.) leaves. Plants were grown in the greenhouse in nutrient solution. Chlorophyll (Chl), Fe, S, Mg, and Mn concentrations and spectral properties were determined on the youngest fully expanded leaf when deficiency symptoms were clearly manifested. In all species, mineral deficiency affected leaf concentration of the deficient element and also of other elements. Nutrient deficiency reduced Chl concentration and A, and increased R and T. Iron deficiency severely affected all species, and corn was the species most sensitive to all deficiencies. Reflectance, A, and T spectra of leaves were correlated with leaf Chl concentration. Our results suggested that all nutritional deficiencies reduce leaf Chl concentration, and subsequently this reduction increases leaf R and T, decreases leaf A, and shortens the red‐edge position, defined as the inflection point that occurs in the rapid transition between red and near‐infrared. Modifications in leaf spectral properties were not characteristic of nutrient deficiency, but were always observed in the same wavelengths.
Starter Fertilizer and Planting Date Effects on Corn Rotated with Cotton
Authors: Mascagni Henry J. , Boquet Donald J.
Published: July 2010

Corn (Zea mays L.) has become an important crop used in rotation with cotton (Gossypium hirsutum L.) in the mid‐South region of the USA, but there has been little research on cultural practices for corn in this cropping system. The objective of this study was to determine if starter fertilizer has beneficial effects on corn growth and grain yield at different planting dates. Starter fertilizer and planting date effects were evaluated for corn in field experiments on a Commerce silt loam (fine‐silty, mixed, nonacid, thermic Aeric Fluvaquent) for 3 yr (1991 through 1993). Six hybrids were evaluated with two starter fertilizer treatments at four planting dates. Starter treatments were (i) ammonium polyphosphate (11‐37‐0 N‐P‐K) applied in‐furrow and (ii) a control with no starter fertilizer. Planting dates were mid‐March, early April, mid‐April and late April or early May. Yield response to planting date was not consistent across years; in two of three years, however, planting later than early April decreased yield. The starter fertilizer increased grain yield in two of the three years. Yield response to starter fertilizer was not consistent across years, hybrids, or planting dates. The planting date × starter interaction for yield was significant in two of three years and the hybrid × starter interaction for yield was significant in one of three years. Starter fertilizer increased early‐season plant height by 2 to 36% and increased grain yield across planting dates from 0.5 to 1.4 Mg ha−1 in 1991 and 0.4 to 1.0 Mg ha−1 in 1993. There was no yield response to starter in 1992. Application of starter fertilizer, averaged across hybrids and years, reduced harvest grain moisture 5% and days to silking by 3 to 5 d. In this mid‐South study, in‐furrow N‐P starter fertilizer increased early‐season corn plant height and grain yield and decreased the number of days to silking of corn rotated with cotton.
Genotypic Interactions with Potassium and Nitrogen in Cotton of Varied Maturity
Authors: Pettigrew William T. , Heitholt James J. , Meredith William R.
Published: July 2010

The development of late‐season K deficiency symptoms in cotton (Gossypium hirsutum L.) fields has become more frequent in the Mid‐South and Far West U.S. production regions. In this study, the objectives were to determine how yield and quality of lint produced by cotton genotypes of varying maturities are affected by different rates of soil applied K and N fertilization. Eight cotton genotypes representing a range of maturities and regional adaptations were studied in Mississippi in 1991 and 1992. All plots received a preplan! application of 112 kg ha−1 N and half the plots also received a 38 kg ha−1 sidedress application of N. Within each N treatment, half the plots received 112 kg ha−1 K surface applied and preplant incorporated, with the remaining plots receiving 0 kg ha−1 K. Averaged across years and N treatments, the K deficiency associated with the 0 K treatment reduced lint yield (9%), boll mass (7%), lint percentage (1%), and seed mass (4%). Varying the N fertilization did not benefit these parameters. The high N treatment reduced lint yield 3% (P = 0.07) and lint percentage 1% (P = 0.06) when coupled with the 0 K treatment. All genotypes suffered yield reductions caused by the K deficiency, except for ‘HS 26’, which was not adapted for production in the Mississippi Delta. Potassium deficiency produced reductions in fiber elongation (3%), 50% span length (1%), uniformity ratio (1%), micronaire (10%), fiber maturity (5%), and perimeter (1%) in all genotypes. Nitrogen application above the 112 kg ha− rate did not increase the lint yield under the growing conditions of our study. The data indicate that genotype was not of importance when dealing with K fertility. The deficiency itself, however, must be dealt with to avoid significant reductions in the yield and quality of fiber produced.
Modeling Preemergent Maize Shoot Growth: II. High Temperature Stress Conditions
Authors: Weaich Karl , Bristow Keith L. , Cass Alfred
Published: July 2010

High soil temperatures are a significant constraint to crop establishment. Exposure of preemergent maize (Zea mays L.) to temperatures in excess of 40°C stops shoot elongation and may also damage the seedling, reducing subsequent shoot growth in the physiological temperature range (9 to 40°C). At present, there is little quantitative understanding of the effects of high temperature stress on preemergent maize shoot growth. Consequently, existing maize emergence or preemergent maize shoot growth models are restricted to the physiological temperature range. The work described in this paper quantified the effect of supramaximum temperatures (temperatures greater than 40°C) on maize shoot growth, and in particular on its component parts, the coleoptile and first internode. The major impact of supramaximum temperatures on shoot growth was due to a severe reduction in the first internode growth rate, which was correlated with the maximum temperature reached during the day. We also found that, under diurnally varying temperature conditions, coleoptile growth ceased only at 45°C, rather than at 40°C as found previously in constant temperature experiments. Inhibition of shoot growth due to high temperature damage was alleviated when seedlings were grown in the physiological temperature range for 33 h. Based on these findings, a model was developed that can predict shoot growth of seedlings exposed to supramaximum temperatures. The model successfully predicted shoot growth of seedlings exposed to supramaximum temperatures as a part of the diurnal cycle. The model was unable, however, to predict seedling recovery from high temperature damage.
Simulating Alamo Switchgrass with the ALMANAC Model
Authors: Kiniry James R. , Sanderson Matt A. , Williams Jimmy R. , Tischler Charles R. , Hussey Mark A. , Ocumpaugh William R. , Read James C. , Van Esbroeck George , Reed Roderick L.
Published: July 2010

A model for forage yield with adequate details for leaf area, biomass, nutrients, and hydrology would be valuable for making management decisions. The objectives of this study were to develop Alamo switchgrass (Panicum virgatum L.) parameters for the Agricultural Land Management Alternatives with Numerical Assessment Criteria (ALMANAC) model and demonstrate its accuracy across a wide range of environments. Derived plant parameters included potential leaf area index (LAI), potential biomass growth per unit intercepted light, optimum nutrient concentrations, and growth responses to temperature. The model's simulated yields accounted for 79% of the variability in measured yields for one‐cut and two‐cut harvest systems from six diverse sites in Texas in 1993 and 1994. Simulated yields for three locations differed in sensitivity to potential LAI, heat units to maturity, radiation use efficiency (RUE), and soil depth. The ALMANAC model shows promise as a management tool for this important forage and bioenergy crop.
Measuring Soil Water Content in the Laboratory and Field with Dual‐Probe Heat‐Capacity Sensors
Authors: Tarara Julie M. , Ham Jay M.
Published: July 2010

Dual‐probe heat‐capacity sensors were constructed and tested in laboratory and field conditions to determine their application for measuring volumetric soil water content (θv). The dual‐probe technique uses a transient heat pulse and a temperature sensor to determine the volumetric heat capacity of the soil (pcp), which can be subsequently converted to θv for a nonswelling soil if bulk density is known. In 1994, 24 dual‐probes were simultaneously tested using a multiplexed data acquisition system. In the laboratory, probes were calibrated to the known heat capacity of water. Following calibration, the probes correctly estimated pcp of glass beads and water‐saturated glass beads to within 2.2 and 0.2% of their calculated values, respectively. Gravimetric and dual‐probe estimates of θv were compared using the Tempe pressure cell technique to desorb soil columns. The two methods agreed to within 0.03 m3 m−3 and 0.04 m3 m−3 in two soil types, over a range of θv from 0.45 m3 m−3 to 0.10 m3 m−3; estimates of the change in θv (Δθv) between desorption steps agreed to within 0.01 m3 m−3. In the field, beneath bare soil, estimates of θv among three dual‐probes installed at the same depth agreed, on average, to within 0.02 m3 m−3. The probes detected Δθv within 30 min during the 21‐d field trial. Dual‐probe and gamma‐attenuation measurements of θv agreed to within 0.05 m3 m−3. In 1995, probe design was improved to produce more robust, reliable instruments. Sixteen probes were installed 10 cm beneath a drip‐irrigated row crop. A consistent difference in θv of ≈0.10 m3 m−3 between mulch‐covered and bare soil beds was detected during the 25‐d trial. The dual‐probe heat‐pulse technique for measuring θv has direct applicability in agronomic and horticultural production, where small‐scale, automated measurements of θv are needed.
Yield Accumulation in Irrigated Sugarcane: II. Utilization of Intercepted Radiation
Authors: Muchow Russell C. , Evensen Carl I. , Osgood Robert V. , Robertson Michael J.
Published: July 2010

Intercepted radiation is a major driving variable of crop production under high‐input irrigated conditions. Quantitative information on the utilization of radiation in yield accumulation allows extrapolation beyond the current season and location, and when this information is incorporated into crop growth simulation models, the effect of crop age on the productivity of different cultivars can be examined under different climatic conditions. This paper examines the differential performance of high‐yielding sugarcane (Saccharum spp. hybrids) crops in terms of the amount of short‐wave solar radiation intercepted (Si) and the efficiency of use of intercepted radiation (RUE) in biomass production. Biomass accumulation during the 12‐ to 24‐mo crop cycle was examined for two experiments conducted in Hawaii, and three experiments conducted in tropical Australia from 1991 to 1993. The analysis showed that (i) RUE was much less for growth after 12 mo than in the first 12 mo; (ii) maximum RUE of sugarcane approaches 2.0 g MJ−1; (iii) biomass accumulation beyond 12 mo was not related directly to radiation utilization; and (iv) cultivars differed in S19 but differences in RUE could not be unequivocally assessed due to the confounding effect of variable recovery of trash in biomass estimates. It is concluded that stalk death and consequent biomass loss are important factors contributing to yield variation in sugarcane crops growing for 12 to 24 mo, with a yield plateau occurring at variable crop ages during the second year of growth.
AEGIS/WIN: A Computer Program for the Application of Crop Simulation Models Across Geographic Areas
Authors: Engel Thomas , Hoogenboom Gerrit , Jones James W. , Wilkens Paul W.
Published: July 2010

Computer‐based biological simulation models have been used to calculate the effects of different management practices and land‐use systems on agricultural production and to assess the impact of these practices on the environment. Using spatial visualization techniques to display simulation results can significantly improve the presentation and interpretation of these analyses. The objective of this study was to develop a computer program for the spatial application of crop models as well as the analysis and visualization of modeled results. The Agricultural and Environmental Geographic Information System for Windows (AEGIS/WIN) links the simulation system Decision Support System for Agrotechnology Transfer (DSSAT) v3 with the geographic mapping tool ArcView 2. The interface between the two systems was programmed using Avenue, an object‐oriented macro programming language. This interface handles automatic data and command transfers between the simulation system and the mapping tool and does not require any modifications of DSSAT v3. The main spatial input for AEGIS/WIN is a coverage in the form of a digital map of a farm, a region, or any other area. DSSAT is used to create model input files and to execute the various crop management scenarios for the selected coverage. The crop model outputs can be imported and joined with the original selected land‐use map in ArcView. The simulation results can be analyzed with AEGIS/WIN using simple statistics and bar charts. AEGIS/WIN's most important feature is the display of thematic maps of simulated crop yield, yield components, and other related agronomic and environmental variables. The system was applied to study the spatial yield variability of peanut (Arachis hypogaea L.) for a research farm in Georgia. AEGIS/WIN was shown to be an effective tool for the spatial application of crop simulation models and for the analysis and visualization of simulated outputs.
Dollar Spot Severity as Influenced by Trinexapac‐ethyl, Creeping Bentgrass Cultivar, and Nitrogen Fertility
Authors: Golembiewski Robert C. , Danneberger T. Karl
Published: July 2010

Dollar spot (Sclerotinia homoeocarpa F.T. Bennett) is a widely distributed and destructive pathogen of turfgrass in the United States. A 2‐yr field study was conducted at Columbus, OH, to determine the influence of a plant growth regulator, creeping bentgrass (Agrostis stolonifera L.) cultivars, and N fertility on dollar spot severity. ‘Crenshaw’ creeping bentgrass was seeded alone or in a 50:50 blend by weight with ‘Penncross’ creeping bentgrass. Plots were fertilized at 0, 24.4, or 48.8 kg N ha−1 per application. One‐half of each plot received trinexapac‐ethyl (TE) [4‐(cyclopropyl‐α‐hydroxymethylene)‐3,5‐dioxo‐cyclohexanecarboxylic acid methyl ester] at 0.8 L ha−1. The TE and fertilizer treatments were initiated in May 1995 and 1996 with four subsequent applications made at 30‐d intervals. Initially, the cultivar blend reduced the rate of dollar spot development compared with Crenshaw alone; however, neither the blend nor Crenshaw provided commercially acceptable dollar spot suppression throughout the study. Both TE and N fertilization significantly (P ≤ 0.05) reduced dollar spot severity over the 2‐yr period. Trinexapacethyl applied alone effectively suppressed dollar spot activity, but efficacy increased with increasing N rates. Dollar spot symptoms decreased and thatch thickness increased at elevated N levels. During this 2‐yr study, interactions between TE and N fertility resulted in a significant (P ≤ 0.05) reduction in dollar spot severity. Thus, on golf course fairways where dollar spot may be severe, incorporation of these two treatments into a turfgrass management program will enhance dollar spot suppression and reduce fungicide inputs.
Seed Maturity in Four Cool‐Season Forage Grasses
Authors: Berdahl John D. , Frank Albert B.
Published: July 2010

Excessive seed shattering of perennial grasses in the Triticeae tribe results in major economic losses to seed producers. In this 4‐yr field study, heat units expressed as growing degree‐days (GDD) after anthesis were related to seed development in tetraploid crested wheatgrass [Agropyron desertorum (Fisch. ex Link) Schultes], Russian wildrye [Psathyrostachys juncea (Fisch.) Nevski], intermediate wheatgrass [Thinopyrum intermedium (Host) Barkw. & D.R. Dewey], and western wheatgrass [Pascopyrum smithii (Rydb.) A. Löve]. Seed quality at different stages of development was assessed by germination percentage and emergence of seedlings from a 5.0‐cm planting depth in a Parshall fine sandy loam soil (coarse‐loamy, mixed Pachic Haploborolls). Water concentration of the seed at maximum seed mass (dry wt. basis) ranged from 303 g kg−1 for intermediate wheatgrass to 376 g kg−1 for western wheatgrass. Seed mass was closely associated with seed vigor in all four grass species, as evidenced by correlation coefficients between seed mass and seedling emergence of 0.88** for crested wheatgrass, 0.93** for Russian wildrye, 0.92** for intermediate wheatgrass, and 0.77** for western wheatgrass. Plots sampled at the stiff‐dough stage had a water concentration of approximately 350 g kg−1 (dry wt. basis), and the seed sample was at or near maximum seed mass. Seed mass and germination would not be seriously compromised and seed yield losses from shattering would be reduced if windrowing were completed about 50 GDD or 2 to 3 calendar days before maximum seed mass is attained.
Entry ✕ Environment Interactions for Alfalfa Forage Quality
Authors: Sheaffer Craig C. , Cash Dennis , Ehlke Nancy J. , Henning Jimmy C. , Jewett Jane Grimsbo , Johnson Keith D. , Peterson Michael A. , Smith Mark , Hansen Julie L. , Viands Donald R.
Published: July 2010

Alfalfa (Medicago sativa L.) cultivars are available that produce high‐quality forage; however, information is lacking on the consistency of cultivar forage quality over environments and the influence of stand age on quality. Our objectives were to evaluate alfalfa cultivars for consistency of forage quality over time and environments and to test the validity of sampling seeding‐year stands for forage quality. We sampled eight alfalfa entries (seven cultivars and one experimental germplasm) at bud and flower maturity stages in the seeding year (one harvest) and first production year (two harvests) in six states (Indiana, Kentucky, Minnesota, New York, Washington, and Wisconsin). ANOVA and orthogonal contrast analyses were conducted to assess entry × environment interactions for forage quality. First‐cut forage in the first production year had lower forage quality than third‐cut forage, and differences between entries were more pronounced at the first cutting. Including seeding‐year data in the ANOVA produced a complex location × entry × stand age interaction, indicating that seeding‐year data alone were insufficient to characterize alfalfa entries for forage quality. ‘Cimarron VR’, ‘Arrow’, and ‘5432’ had the greatest stability for forage quality and could serve as high, medium, and low forage‐quality checks, respectively, in forage quality testing trials. ‘WL 322 HQ’ and ‘Pacesetter’ often had high quality, but were not stable for forage quality over environments. Correlations between crude protein, acid detergent fiber (ADF), neutral detergent fiber (NDF), and in vitro digestible dry matter were consistent across locations, entries, cuttings, and maturities. The high correlation between NDF and ADF (r > 0.97, P < 0.05) suggests that it may not be necessary to use both procedures to predict entry differences in forage quality.
Phosphorus and Potassium Placement Effects on Early Growth and Nutrient Uptake of No‐Till Corn and Relationships with Grain Yield
Authors: Mallarino Antonio P. , Bordoli José M. , Borges Rogerio
Published: July 2010

Early plant growth and grain yield of no‐till corn (Zea mays L.) are usually lower than for conventionally tilled corn in the northern U.S. Corn Belt. Root‐zone fertilization is likely to enhance early growth and increase yields. This study evaluated the effects of P and K placement on early growth and P and K uptake of no‐till corn, and on relationships between these effects and grain yield response to placement. Ten long‐term P and K trials (5 trials each, P and K) were established in 1994 at five research centers and were evaluated for 3 yr; 11 1‐yr P‐K trials were established in farmers' fields (1994–1996). Treatments several P and K rates (0–56 kg P ha−1; 0–132 kg K ha−1) banded with the planter 5 cm beside and below the seeds and broadcast or deep‐banded at a 13‐ to 18‐cm depth before planting. Soil samples were collected before applying the treatments from the 0‐ to 7.5‐cm and 7.5‐ to 15‐cm depths. Soil‐test P (0‐15 cm) ranged from very low to very high across sites and soil‐test K ranged from optimum to very high. Banded P (deep or shallow) increased early growth and P uptake more than the broadcast placement did at most trials. Phosphorus increased yields only in very low and low testing soils, and there was no response to P placement. Banded K (deep or shallow) seldom affected early growth, but usually increased K uptake. Potassium increased yields in several soils that tested optimum or higher in soiltest K, and yields were higher when K was deep banded. Planting onto a fall‐applied coulter‐knife track without applying P or K often increased early growth and nutrient uptake, but seldom increased yields. Early growth and nutrient uptake responses to banded P did not translate into higher yields. Small but frequent yield responses to deep‐banded K were not related to increased early growth, but could be partly explained by increased K uptake. Judging potential effects of P and K placement on grain yields of no‐till corn based on effects (or lack of effect) on early growth may be misleading for soils that are not extremely deficient in these nutrients.
Banded Wetting Agent and Compaction Improve Barley Production on a Water‐Repellent Sand
Authors: Crabtree William L. , Gilkes Robert J.
Published: July 2010

Large areas of cropland in Western Australia exhibit severe annual water repellency. Crop establishment is frustrated by the staggered emergence of plants, despite significant amounts of rain falling prior to the desired time of seeding. Three techniques were used to investigate improvements in barley (Hordeum vulgare L.) establishment on a water‐repellent sand: (i) spraying various rates of banded (2 cm wide) wetting agent while furrow seeding with press wheels, (ii) seed placement either in a furrow or in the side of a ridge, and (iii) compaction with press wheels or a Flexi‐Coil land packer. The application of wetting agent increased seedling emergence from 110 to 170 plants m−2, dry matter production from 4.2 to 6.01 t ha−1 and grain yield from 1.96 to 2.60 t ha−1, despite more weeds occurring with increasing rate of banded wetting agent. Use of press wheels, which also resulted in a furrow sowing condition, increased seedling emergence from 72 to 101 plants m−2 and grain yield from 1.70 to 2.13 t ha−1. In the absence of heavy press wheel compaction, furrow sowing at 18‐cm row spacings with full soil disturbance had no effect on seedling emergence or grain yield. The application of wetting agent increased topsoil wetting. Increased soil wetting may have increased plant nutrient availability (from fertilizer and soil), reduced soil water evaporation, and possibly reduced water loss to subsoil on this duplex soil. The optimum degree of compaction required on water‐repellent soils is not known and needs further research.
Using Near Infrared Reflectance Spectroscopy to Schedule Nitrogen Applications on Dwarf‐Type Bermudagrasses
Authors: Rodriguez Ian R. , Miller Grady L.
Published: July 2010

Due to the high rates of N fertility necessary for producing high‐quality turfgrasses, quick, reliable methods of determining the N status of turfgrasses would be valuable management tools. The first objective of this study was to evaluate the use of near infrared reflectance spectroscopy (NIRS) to schedule N fertilization on two dwarf‐type bermudagrasses [Cynodon dactylon (L.) Pers. × C. transvaalensis Burtt Davy]. The second objective was to test the accuracy of NIRS‐predicted mineral tissue concentrations. The third objective was to study the effect of N fertility on thatch development. ‘Tifdwarf’ and ‘FloraDwarf’ bermudagrasses grown on sand–peat (9:1 by volume) were subjected to five treatments using time, NIRS‐predicted N thresholds, and a visual quality rating threshold to schedule applications of (NH4)2SO4 for 20 wk per growing season in 1997 and 1998. There were positive linear relationships between total Kjeldahl nitrogen (TKN) and NIRS‐predicted N in 1997 (r2 = 0.76; slope = 0.96) and 1998 (r2 = 0.92; slope = 1.06). NIRS‐scheduled fertility resulted in similar quality with less fertilizer than time or visual quality‐based fertility. The NIRS mineral concentration predictions for K, Ca, Mg, Fe, Zn, Mn, and Cu were positively correlated with traditional laboratory methods, but there was not sufficient precision in measurements to use NIRS for determination of these nutrients. Thatch development and yields were greater in treatments receiving higher rates of fertilizers, suggesting that excessive growth rates due to high rates of applied fertilizer may have contributed to thatch development.
Digital Acquisition and Measurement of Peanut Root Minirhizotron Images
Authors: Pateña George , Ingram Keith T.
Published: July 2010

Video, photo, or in situ image capture and analysis from minirhizotrons is time‐consuming. Computerized root image analysis is expensive and subject to large background error. This paper describes a fast, simple, and accurate method for (i) capturing minirhizotron images through low‐cost hardware upgrade of existing minirhizotron equipment, and (ii) processing digital images using low‐cost software. This system was developed to monitor root distribution in peanut (Arachis hypogaea L.). Digital images were recorded from a minirhizotron camera directly to a laptop computer hard drive instead of using videotape. This reduced image acquisition time by 36% and eliminated problems associated with manipulating video players. The image analysis system uses a mouse pointer to trace root length and diameter on a computer screen and calculates the distance traversed by the mouse pointer. A paired t‐test on accuracy using wires of known length showed no significant difference (P = 0.10) between actual and measured lengths.
Food Safety Assessment of Genetically Modified Crops
Authors: Kaeppler Heidi F.
Published: July 2010

Following the production of the first transgenic plants, health issues concerning the safety of using genetically modified (GM) crops in foods and feeds have been discussed, debated, and evaluated. The main concerns regarding GM foods include toxin or allergen production, changes in nutrient levels, and development of antibiotic resistance. The U.S. Food and Drug Administration established extensive guidelines to address the concerns and ensure the safe commercial introduction of GM crops for use in food or feed. The guidelines were developed through evaluation of scientific data from several disciplines related to genetic engineering and food safety, and consultation with experts from around the world. Foods containing GM crops meeting the FDA guidelines are deemed to be as safe and nutritious as their non‐GM counterparts already on the market.
Soil Physical Properties and Tomato Yield and Quality in Alternative Cropping Systems
Authors: Colla Giuseppe , Mitchell Jeffrey P. , Joyce Brian A. , Huyck Leisa M. , Wallender Wesley W. , Temple Steve R. , Hsiao Theodore C. , Poudel Durga D.
Published: July 2010

The Sustainable Agriculture Farming Systems (SAFS) Project has studied the transition to low‐input and organic alternatives in California's Sacramento Valley. This project compares a 4‐yr rotation of tomato (Lycopersicon esculentum Mill.), safflower (Carthamus tinctorius L.), corn (Zea mays L.), and wheat (Triticum aestivum L.) followed by double‐cropped bean (Phaseolus vulgaris L.) in the conventional system and oat (Avena sativa L.)–purple vetch (Vicia benghalensis L.) in the low‐input and organic systems. A conventional 2‐yr rotation (tomato–wheat) is also studied. In 1997 and 1998, we evaluated the transition to alternative systems on soil bulk density, water holding capacity, infiltration and storage, water use efficiency, and ‘Brigade’ tomato yield and quality. No differences in laboratory determinations of soil bulk density and water holding capacity were found; however, in situ water holding capacity was highest in the organic system, lowest in the conventional 4‐yr rotation and intermediate in the low‐input and conventional 2‐yr rotations. In 1998, infiltration during 3‐h irrigations was 0.028 m3 m−1 for the conventional, and 0.062 m3 m−1 and 0.065 m3 m−1 for the low‐input and organic systems, respectively. Similar results were observed in 1997. The alternative systems required more water per irrigation for uniform application, resulting in higher soil water content in the organic systems throughout 1998. Evapotranspiration was higher in the conventional systems in both years relative to other systems. Tomato yields did not differ among systems in either year. Fruit quality was highest in the conventional 4‐yr system.
Effects of Mulching on Biomass, Nutrients, and Soil Water in Banana Inoculated with Nematodes
Authors: McIntyre Beverly D. , Speijer Paul R. , Riha Susan J. , Kizito Fred
Published: July 2010

The objective of this study was to determine whether mulching mitigated the impact of nematodes on banana (Musa AAA) inoculated with Radopholus similis (Cobb) Thorne and Helicotylenchus multicinctus (Cobb) Golden. The study was conducted at International Institute of Tropical Agriculture's (IITA's) Sendusu station, Uganda. Treatments included mulched and bare soil with or without nematode inoculation. Mulched treatments produced over three times more biomass than bare soil treatments. This increase in biomass was likely due to improved fertility as a result of mulching, since mulched treatments had higher concentrations of soil organic C, P, and exchangeable K and Mg, and foliar K. Mulched banana took up more water from both the 0‐ to 0.3‐m and 0.3‐ to 0.5‐m depths than banana grown without mulch and soil water recharged more quickly in the mulched treatments as a result of increased porosity from 0‐ to 0.3‐m depth. Nematode inoculation had little effect on biomass or foliar nutrient concentrations of P, K, Ca, and Mg in the bare soil treatments. In contrast, in the mulched treatments nematode inoculation reduced banana biomass and yield. In both cases, more root necrosis was observed in the inoculated treatments. It appears that growth was so restricted by low fertility in the bare soil treatment that nematode damage was not a limiting factor. As mulching increased soil fertility, nematode damage did appear to restrict the growth potential of banana. Our study suggests that mulching may mitigate the impact of nematodes on bananas when applied to low fertility systems.