bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seed Maturity, Storage Time and Temperature, and Media Treatment Effects on Germination of Two Wild Sunflowers
Authors: Seiler Gerald J. 
Published: July 2010

AbstractDormancy in achenes (seeds) of wild sunflower (Helianthus) species ensures that they do not germinate in temperate climates until conditions are optimal for seedling survival. However, high achene dormancy results in low germination of achenes, precluding utilization of many wild species for domestic purposes. Interest in the use of native Helianthus species for domestic purpose such as low‐maintenance ornamentals, revegetation, cut flowers, and genetic improvement of cultivated sunflower has recently increased. The objectives of this study were to evaluate germination media to overcome dormancy and enhance germination of two annual species, H. annuus L. and H. petiolaris Nutt., and to evaluate the influence of achene maturity and storage time and temperature on germination. A 1 mM gibberellic acid (GA3) medium was the most effective stimulant in laboratory tests for enhancing germination of H. annuus. Germination of treated achenes was 81%, compared with 38% for the control. Germination of H. petiolaris achenes was 60% with the 1 mM GA3 medium, compared with 9% for the water control. This GA3 medium enhanced germination regardless of achene maturity, storage time, or storage temperature. When averaged over all media, achene maturities, and storage times and temperatures, H. annuus had a germination of 41%, compared with only 21% for H. petiolaris. The age of the achenes at harvest influenced germination. Achenes harvested 20 d after flowering generally had greater germination than those harvested 40 d after flowering, especially for H. petiolaris. Storage time and temperature could not overcome the dormancy imposed prior to germination in either species. Utilization of germination media to enhance germination of wild Helianthus species will facilitate their use for domestic purposes.
Temperature and Sowing Date Affect the Linear Increase of Sunflower Harvest Index
Authors: Bange Michael P. , Hammer Graeme L. , Rickert Kenneth G. 
Published: July 2010

AbstractThe linearity of daily linear harvest index (HI) increase can provide a simple means to predict grain growth and yield in field crops. However, the stability of the rate of increase across genotypes and environments is uncertain. Data from three field experiments were collated to investigate the phase of linear HI increase of sunflower (Helianthus annuus L.) across environments by changing genotypes, sowing time, N level, and solar irradiation level. Linear increase in HI was similar among different genotypes, N levels, and radiation treatments (mean 0.0125 d−1), but significant differences occurred between sowings. The linear increase in HI was not stable at very low temperatures (down to 9°C) during grain filling, due to possible limitations to biomass accumulation and translocation (mean 0.0091 d−1). Using the linear increase in HI to predict grain yield requires predictions of the duration from anthesis to the onset of linear HI increase (lag phase) and the cessation of linear HI increase. These studies showed that the lag phase differed, and the linear HI increase ceased when 91% of the anthesis to physiological maturity period had been completed.
Software for Mapping and Analyzing Weed Distributions: gWeedMap
Authors: Krueger David W. , Coble Harold D. , Wilkerson Gail G. 
Published: July 2010

AbstractThe spatial pattern of weeds in a field is often patchy. This pattern can be visualized with maps created by geographical information system (GIS) software. However, this software is often difficult to use and/or expensive, especially if not all of the GIS functionality is needed. The objective of this project was to develop a means of easily and economically generating weed maps. This was accomplished by creating a PC‐based Windows software tool to generate weed maps from scouting information. The scout enters weed data that has been collected in a gridded, systematic sampling protocol. From this information, the program creates a map for each weed species in the field. Scouting data can be density, percent cover, or any other type of measurement. Five data ranges are displayed on the map, with the user specifying the data values and map colors associated with each range. Various statistics are calculated, such as the average density of each species. Weed diversity in each field is determined with Shannon's diversity index and evenness index. These indices are also calculated with the density data weighted by the competitiveness of each weed species. This gives the weed ecologist a quantitative measure of the competitive diversity, which is related to the impact of the weed population on yield loss.
Thrips Injury Can Reduce Peanut Yield and Quality under Conditions of multiple Stress
Authors: Funderburk Joe E. , Gorbet Dan W. , Teare Iwan D. , Stavisky Julianne 
Published: July 2010

AbstractSevere injury from tobacco thrips [Frankliniella fusca (Hinds)] to seedling peanut (Arachis hypogaea L.) has not been documented to reduce yield and quality. However, thrips injury may be economically important when combined with another factor, such as postemergence herbicide injury. This note reports results of a field experiment in which control of tobacco thrips during an unusually dry early season greatly increased peanut seed yield and quality. ‘Florunner’ peanut was grown using preplant and postemergence herbicides for weed control. Treatments consisted of an untreated control and four labeled insecticides applied at planting or soon after crop emergence. Populations of adult tobacco thrips were significantly suppressed by aldicarb [2‐methyl‐2‐(methylthio) propionaldehyde O‐(methylcarbamoyl) oxime]; all insecticides significantly suppressed immature thrips. Aldicarb, the most efficacious insecticide treatment, significantly improved peanut yield by 32% and quality as determined by percentage of total sound mature kernels. All but one of the remaining insecticide treatments significantly improved seed yield, with increases ranging from 9 to 31%. Rainfall was extremely low early in the growing season, and (based on 41 yr of records at the site) drier conditions occur 10% of the time. This is a frequency great enough to matter, but low enough to make further research difficult. The observations reported here suggest that early‐season moisture stress intensifies peanut yield and quality losses associated with combined injury from thrips and postemcrgence herbicides.
Medic Planting Date Effect on Dry Matter and Nitrogen Accumulation When Clear‐Seeded or Intercropped with Corn
Authors: Jeranyama Peter , Hesterman Oran B. , Sheaffer Craig C. 
Published: July 2010

AbstractIntercropping annual forage legumes with row crops has been proposed as a strategy to control erosion, suppress weeds, and contribute biological N to companion or subsequent crops. This experiment evaluated the effect of planting date of two annual medic species [burr and snail medic, Medicago polymorpha L. and M. scutellata (L.) Mill.] on yield and N accumulation of both medic and interseeded corn (Zea mays L.). Medics were either clear‐seeded (i.e., monocropped) or interseeded into corn at five planting dates from 7 May to 13 July in each of two years at East Lansing, MI, on a Capac loam (fine‐loamy, mixed, mesic Aerie Endoaqualf). Clear‐seeded medic produced up to 3 Mg ha−1 of dry matter at 60 d after planting. In the interseeding system, medic dry matter yields were only 50% of yield in a clearseeded system. Average aboveground medic N concentration was 50 and 20 kg ha−1 in clear‐seeded and interseeded systems, respectively. Interseeding at corn planting produced the greatest medic dry matter, but also was associated with the greatest reduction in corn yield. Corn yields were not reduced by interseeding medic 28 d after com planting. Interseeding medic into corn was associated with a positive yield response (3–25%) of subsequent corn grain. Medics reduced fertilizer needs of corn in the subsequent year by 37 kg N ha−1.
Field Validation of Soil Solute Profiles in Irrigated Cotton
Authors: Norton E. Randall , Silvertooth Jeffrey C. 
Published: July 2010

AbstractManagement of water and fertilizer N are important aspects of cotton production in the desert Southwest. GOSSYM, a cotton growth simulation model, has been used extensively to manage these inputs. Our objectives were to further validate GOSSYM by comparing model‐simulated and measured soil NO‐3‐N profiles, to evaluate GOSSYM's potential as a management tool under irrigated growing conditions in the desert part of the U.S. Cotton Belt, and to address questions about the way GOSSYM simulates NO‐3‐N movement through the soil profile in relation to irrigation water management (which in turn affects prediction of plant growth and development). We compared measured profiles of NO‐3‐N with GOSSYM‐simulated profiles. Soil profile samples were obtained from an existing N‐management field study, a split‐plot within a randomized complete block design. Mainplots were upland and pima cotton (G. hirsutum L. cv. DPL 5415 and G. barbadense L. cv. Pima S‐7, respectively). Subplots were a check (0 fertilizer N) and three other N‐management strategies. The cotton was grown on a Casa Grande sandy loam [fine‐loamy, mixed, hyperthermic Typic Natrargid (reclaimed)] near Maricopa, AZ, in 1994 and 1995. Fertilizer N rates ranged from 0 to 350 kg ha−1 in 1994 and 0 to 392 kg ha−1 in 1995. Soil samples taken to a depth of 120 cm in 30‐cm increments were analyzed for NO‐3‐N. Comparisons of simulated and actual NO‐3‐N profiles revealed tendencies in GOSSYM to overestimate NO‐3‐N leaching out of the effective rooting zone, resulting in simulated N stresses midseason. When GOSSYM simulated an N stress, between 50 and 75% of the simulated soil NO‐3‐N values were greater than the measured values, yet the simulated N stress still occurred. This indicates possible limitations in GOSSYM's ability to adequately predict N uptake by plants. The dynamic soil N portion of the model needs further refinement, particularly for cotton production under irrigated desert conditions.
Foliar Fertilization of Soybean at Early Vegetative Stages
Authors: Haq Mazhar U. , Mallarino Antonio P. 
Published: July 2010

AbstractThe yield response of soybean [Glycine max (L.) Merr.] to foliar fertilization during reproductive stages has been inconsistent. This study evaluated soybean responses to foliar applications of a 3–8–15 (N–P–K) fertilizer at early vegetative stages in 48 trials conducted on Iowa soils that tested mostly optimum or above in P and K. In 1994, the treatments were a control, single applications of 19, 28, or 38 L ha−1 at the V5 stage, and 38 or 56 L ha−1 split as one‐half at the V5 stage and one‐half 8 or 9 d later. In 1995 and 1996, only the single rate of 28 L ha−1 and the split rate of 38 L ha−1 were used. The lowest and highest volumes used encompassed N‐P‐K rates of 0.8‐2.1‐3.9 to 2.4‐6.3‐11.7 kg ha−1. All treatments were replicated four times. Some or all treatments increased yields in seven sites and decreased yields at two sites. Mean yield increases were 60 kg ha−1 in 1994 (not significant), 30 kg ha−1 in 1995 (not significant), 60 kg ha−1 in 1996, and 54 kg ha−1 across the 48 sites. Differences between treatments were small and inconsistent, and the single application of 28 L ha−1 (one of the lowest rates used) produced the highest mean yield increase across all responsive sites (375 kg ha−1). In 1994, the higher yield responses occurred on ridge‐till and no‐till fields and when the P concentration of young plants was low. No treatment caused leaf burning. Foliar fertilization seldom increased P and K concentrations of leaves at the R2 growth stage and did not affect plant maturity, grain moisture, or the weight of grains. No simple set of measurements explained the occurrence of yield responses. Results of factor and regression analyses suggested that responses tended to occur in soils with high cation exchange capacity, when plant‐available P was low, and/or when rainfall in spring and midsummer was low. This group of variables explained only 14 to 23% of the responses in different years, however. Effective use of foliar fertilization of soybean at early growth stages in areas with predominantly high‐testing soils requires further research to identify the conditions under which positive responses are more likely.
Mechanisms of Corn Tolerance and Velvetleaf Suppressive Ability
Authors: Lindquist John L. , Mortensen David A. , Johnson Blaine E. 
Published: July 2010

AbstractCrops that better tolerate weed competition or preempt resources from weeds may reduce dependence on herbicides for weed control and benefit an integrated weed management program. Irrigated field experiments were conducted to identify morphological traits of corn (Zea mays L.) that enhance its tolerance and weed suppressive ability. Two old (circa 1940) and two modern corn hybrids were grown in mixture with five target densities of velvetleaf (Abutilon theophrasti Medik.) in two years. Corn height and leaf area index (LAI) were measured periodically throughout the growing season. Vertical leaf area distribution was measured at corn anthesis. Quantitative estimates of these traits were obtained for each experimental unit using linear and nonlinear regression analysis. Magnitude of the correlation between these trait estimates and corn yield reduction in mixture with velvetleaf or velvetleaf seed capsule production was used as an indicator of the importance of each trait to the enhancement of corn tolerance or velvetleaf suppressive ability. Canopy traits having highest correlation with corn relative yield in 1995 were maximum LAI (r= −0.38) and crop density (r = −0.24). Those with highest correlation in 1996 were crop density (r = ‐0.36), degree days accumulated between emergence and 50% maximum height (r = 0.34) and LAI (r = 0.19), and vertical leaf area distribution (0.49). Corn canopy traits were not correlated with velvetleaf seed production in 1995. However, vertical leaf area distribution (r = 0.60), maximum LAI (r = −0.32), and corn density (r = −0.26) were correlated with velvetleaf seed production in 1996. Results suggest that increasing maximum corn LAI, rate of canopy closure, or height at which leaf area occurs in the canopy can improve corn tolerance and velvetleaf suppressive ability. These traits can be modified by varying cultural practices such as row spacing and population density, or through breeding.
Establishment of Corn in Rotation with Alfalfa and Rye: Influence of Grazing, Tillage, and Herbicides
Authors: Morris Jennifer L. , Allen Vivien G. , Vaughan David H. , Luna John M. , Cochran Michele A. 
Published: July 2010

AbstractIntegrating livestock into crop rotations offers alternatives for grazing and crop management. Grazing, tillage, and herbicides were evaluated in a randomized block design with four replications for transition from alfalfa (Medicago sativa L.) to corn (Zea mays L.). For the control (T1), alfalfa was overseeded with rye (Secale cereale L.) in October, and corn was no‐till established in early May. For alternative treatments, alfalfa was grazed by cattle (Bos taurus) from July until October. Treatments were: T2, disking prior to rye planting, grazing rye for 12.5 d prior to corn planting, with dicamba (3,6‐dichloro‐2‐methoxybenzoic acid) applied after corn planting; T3, no spring grazing, with glyphosate [N‐(phosphonomethyl)glycine] applied before corn planting; T4, same as T3 plus grazing rye for 1.8 d in early spring; T5, autumn application of glyphosate to alfalfa before planting a rye‐hairy vetch (Vicia villosa Roth) cover crop; and T6, autumn disking before planting rye‐hairy vetch with no herbicides used. System T2 increased suppression of alfalfa and corn plant populations compared with shorter grazing periods. System T4 increased corn plant populations compared with no spring grazing (T3; 3.5 vs. 3.0 plants m−1). Autumn disking (T6) generally provided less control of alfalfa than autumn application of glyphosate (T5). Applying glyphosate before corn planting (T3 and T4) improved corn populations and growth, compared with autumn glyphosate or disking (T5 and T6), and resulted in corn forage yield (23 Mg ha−1) similar to conventional no‐till establishment (T1; 22 Mg ha−1). Herbicides completely killed alfalfa, but grazing alfalfa and rye reduced alfalfa persistence. Grazing could provide benefits to corn production systems while providing forage for cattle.
Simulation of Water Uptake in Maize, Using Different Levels of Process Detail
Authors: Jara Jorge , Stockle Claudio O. 
Published: July 2010

AbstractDaily crop water uptake was simulated using algorithms from three crop simulation models, CropSyst, CERES, and EPIC (listed in order of decreasing process detail). Simulated results were compared with measurements of sap flow and soil water content for maize (Zea mays L.) growing at Prosser, WA, under a wet and a dry irrigation treatment, and with soil water content measurements for nonirrigated maize at Davis, CA. At Prosser, the dry treatment imposed only a mild stress; at Davis, the stress was severe. Simulation variables such as maximum crop evapotranspiration, root density by soil layer, and green leaf area index were provided as daily input. At Prosser, all algorithms performed similarly when simulating crop water uptake. For the wet treatment, the root mean square error (RMSE) was 0.27 to 0.28 mm d−1, and the relative error [RE = 100 (RMSE/Measured average)] was 7.0 to 7.2%. For the dry treatment, simulation accuracy decreased (RMSE = 0.33–0.38 mm d−1; RE = 9.0–10.5%). The time evolution of water uptake simulated by CropSyst better depicted the measured sap flow (water uptake) difference between wet and dry treatments. Simulations of soil water content by layer for the wet treatment, compared with measurements available for 17 d, yielded RMSEs from 0.022 to 0.024 m3 m−3 and REs from 8.5 to 9.2%. For the dry treatment (12 d of measurements), the best simulations were obtained with the water uptake algorithms from CropSyst and CERES, with RMSE = 0.015 m3 m−3 (both models) and RE = 6.4% (CropSyst) and 6.6% (CERES), compared with RMSE = 0.019 m3 m−3 and RE = 8.1% for EPIC. Under the severe water stress at Davis, CropSyst had the best performance. This algorithm simulated changes in soil water content by layer (8 d of measurements available) with RMSE of 0.011 m3 m−3 and RE of 5.0%, while the RMSE and RE values for CERES and EPIC were 0.016 and 0.019 m3 m−3 and 7.6 and 9.0%, respectively. The more process‐oriented algorithm (CropSyst) showed an increasing advantage as water stress severity increased. The EPIC algorithm had the poorest performance under water stress. This could be improved by modifying the value of the water extraction distribution parameter in EPIC, but with this change the wet treatment simulations at Prosser deteriorated substantially, indicative of limitations in EPIC'S simple approach.
Assessing Soil Quality in the Rolling Pampa, Using Soil Properties and Maize Characteristics
Authors: Maddonni Gustavo A. , Urricariet Susana , Ghersa Claudio M. , Lavado Raúl S. 
Published: July 2010

AbstractIntensive land use in the Rolling Pampa of Argentina appears to be reducing soil quality for crop production. Our objective was to establish the best edaphic and/or plant indicators for assessing soil quality with regard to functioning as a medium for crop production. Nine fields with Typic Argiudoll soils were selected for evaluation based on agriculture history and apparent soil structural stability. Soil chemical and physical properties and maize (Zea mays L.) vegetative and reproductive characteristics were measured. Multivariate statistical analyses were applied to the data to determine potential indicators of soil quality. Soil and crop variables explained more than 70% of the variance in soil quality among agricultural histories. The edaphic indicators that showed the greatest change from pristine conditions were organic C, total N, P, Mg, K, B, Ca, and Zn contents and cation exchange capacity. Using crop variables, leaf length, maximum fraction of intercepted photosynthetically active radiation, grain yield, kernel number, prolificacy, and total dry matter at physiological maturity, served to establish a soil quality gradient. Variation of maize growth was associated with edaphic indicators of soil quality and revealed the importance of soil aggregate stability in determine changes in soil quality for crop production.
Cultivar Effects on Oat–Berseem Clover Intercrops
Authors: Holland J. B. , Brummer E. C. 
Published: July 2010

AbstractOat (Avena sativa L.) intercropped with berseem clover (Trifolium alexandrinum L.), an annual forage legume, has economic and biological advantages for use as a rotation crop in the north‐central USA. To investigate the effects of different oat and berseem clover cultivars on the productivity of the intercrop and its components, and to test for interspecific cultivar interactions, we evaluated binary combinations and monocultures of a sample of oat and berseem clover cultivars in three Iowa environments. Oat cultivars varied for oat traits, effects on clover stands and yield, and total intercrop biomass. Berseem clover cultivars varied for forage yield, stand, maturity, damage due to disease and insects, and effects on intercrop biomass. In one environment, only one of seven berseem clover cultivars survived after the first forage harvest. Adding oat to berseem clover reduced total forage and weed yields, clover stands, and relative maturity of clover, but increased total crop biomass and forage plant health. Adding berseem clover to oat did not reduce oat grain or straw yields, and in one year increased oat test weight. Cultivar rankings of each species differed in monoculture vs. intercrop. Interspecific cultivar interactions were not significant for most traits. Greater genetic improvement in the productivity of the oat‐berseem clover intercrop will more likely be achieved by improvement of general agronomic productivity of berseem clover than by trying to enhance specific ecological combining ability of particular oat and berseem clover cultivar combinations.