bluuebunny/crossref_metadata_2025_split huggingface dataset:
Radiation Use Efficiency of an Old and a New Maize Hybrid
Authors: Tollenaar M. , Aguilera A. 
Published: July 2010

AbstractDifferences in dry matter accumulation among crop cultivars can be attributed to differences in either the absorptance of incident photosynthetically active radiation (PAR) and/or the conversion of absorbed PAR into dry matter. This study was conducted to quantify the contribution of radiation use efficiency (RUE, g dry matter MJ−1) to the difference in dry matter accumulation between an old and a new maize (Zea mays L.) hybrid. An old (Pride 5) and a new (Pioneer 3902) maize hybrid were grown during 1989 and 1990 at the Elora Research Station, Ontario, on a London loam (Aquic Hapludalf) soil that had been tile drained. Both hybrids were grown at their respective optimum plant density for grain yield (i.e., 7 plants/m2 for Pride 5 and 8 plants/m2 for Pioneer 3902) and, in addition, the new hybrid was grown at 5 plants/m2 which resulted in a leaf area index (LAI) similar to that of the old hybrid grown at its optimum plant density. Starting at silking, 2‐wk crop growth rates (CGR, kg ha−1 d−1) were measured until physiological maturity, and incident PAR and absorptance of PAR by the three treatments were monitored during three 2‐wk periods after silking. From silking to 6 wk postsilking, PAR absorption did not differ among the two hybrids grown at plant densities that resulted in similar LAIs, but crop growth rate was 19% larger for the new hybrid. The difference in crop growth rate between the old and the new hybrid grown at their respective optimum plant density was 33%; approximately 80% of the difference could be attributed to a higher RUE of the new hybrid. The difference in RUE was not associated with a change in the distribution of PAR across the canopy, i.e., extinction coefficients did not differ among treatments. Dry matter accumulation declined for all treatments after 8 wk postsilking, but the decline was steeper for the old hybrid and the decline was associated with rate of leaf senescence. In conclusion, increased dry matter accumulation of new maize hybrids after silking can be attributed, in a large part, to increased radiation use efficiency.
Differential Weed Suppression Ability in Upland Rice Cultivars
Authors: Garrity D. P. , Movillon M. , Moody K. 
Published: July 2010

AbstractTwenty‐five upland rice (Oryza sativa L.) cultivars were evaluated in 2 yr of field experiments in the Philippines. The research was conducted with low and moderate levels of handweeding to determine the extent of cultivar differences in weed suppression ability. We sought the plant characters that may confer superior competitiveness, and determined their practical significance in contributing to weed management. A large significant variation was observed in the dry weight of weeds (0.84 to 3.89 Mg/ha) associated with the different cultivars. Several cultivars had consistently low weed weights in both weeding treatments across years. Weed weights for the five most competitive cultivars were 75% lower than for those of the five least competitive cultivars. Grain yields were negatively correlated with weed weights, in both weeding treatments in both years (r = −0.48** to −0.59**‐significant at P = 0.01). Plant height, which ranged from 0.73 to 1.35 m, was the character most strongly related to low weed weight, with negative correlations that varied from −0.76** to −0.88** among weeding levels and years. Leaf area index (determined at 60 d after seeding) was also negatively correlated with weed weight, but tiller number was not significantly related to weed weight. The minimum plant height necessary to adequately suppress weeds was approximately 1.00 to 1.15 m. Cultivars with superior yield potential were identified that had a minimum height of 1.0 m, with weed suppression ability similar to the tall traditional cultivars.
Irrigation of Turfgrass with Secondary Sewage Effluent: Soil Quality
Authors: Mancino C. F. , Pepper I. L. 
Published: July 2010

AbstractEffluent and other secondary waters have become important sources of irrigation water in the U.S. Southwest. Information is inadequate relative to potential long‐term effluent irrigation effects on turfgrass and soil chemical quality. The objective of this field research was to determine the influence of secondarily treated municipal wastewater irrigation on the chemical quality of bermudagrass (Cynodon dactylon L.) turf soil (Sonoita gravelly sandy loam: coarse‐loamy, mixed, thermic Typic Haplargid) when compared to similarly irrigated potable water plots. Research plots were irrigated using a 20% leaching fraction. After 3.2 yr of use, effluent water increased soil electrical conductivity by 0.2 ds m−1, Na by 155 mg kg−1, P by 26 mg kg−1, and K by 50 mg kg−1 in comparison to potable irrigated plots. Soil pH was not significantly affected by effluent irrigation. The concentrations of Fe, Mn, Cu, and Zn were found to be within the range considered normal for agricultural soil. Effluent irrigation increased soil total organic carbon and nitrogen during the first 1.3 yr of irrigation only. Total aerobic bacteria populations were similar in all irrigated plots indicating these microbes were not promoted or inhibited by the use of this wastewater. In summary, the irrigation of this turf soil for 3.3 yr with the secondarily treated wastewater used in this study had no serious detrimental effects on soil quality
Evapotransportation, Crop Coefficients, and Leaching Fractions of Irrigated Desert Turfgrass Systems
Authors: Devitt D. A. , Morris R. L. , Bowman D. C. 
Published: July 2010

AbstractReducing irrigation volumes on turfgrass in an arid environment requires close attention to environmental demand. The objective of this research was to quantify the water balances of three turfgrass sites controlled by an evapotranspiration (ET) feedback system and local management. Additional objectives included calculating leaching fractions (LF), crop coefficients (Kc), water savings, and quantifying the variability in potential evapotranspiration (ET0). A 2‐yr study was conducted on three turfgrass sites in southern Nevada growing common bermudagrass [Cynodon dactylon (L.) Pers.] overseeded with perennial ryegrass (Lolium perenne L.). Two vacuum‐drained lysimeters and one automated weather station were placed at each location. One lysimeter was irrigated by input from an ET feedback system while the other was left to local management. The daily Penman combination equation was used to calculate ET0. Hydrologic water balances were maintained on each lysimeter on a weekly basis. A neutron probe was used to measure changes in soil water content in the lysimeters. Actual ET (ET0) varied according to management, with the two golf courses having an average ET0 29% higher than the park site. Differences in ET0 between the park site and golf course sites were attributed to cultural management, in particular fertilizer input. Crop coefficients varied on a monthly basis and between high management vs low management turf. A 4 to 6% error was observed in estimating ET0 among the three sites.
Leaf Emergence and Leaf Duration Related to Thermal Time Calculations in Ceres‐Maize
Authors: Hodges Tom , Evans David W. 
Published: July 2010

AbstractIn the CERES‐Maize model, maize (Zea mays L.) leaf initiation and appearance are modeled using thermal time derived from air temperature. Prior to the elevation of the culm apex, soil temperature, which is calculated by the model from air temperature, is used to calculate thermal time. No provision is made for response differences in leaf appearance rate due to cultivar or daylength. This research compares predicted with actual leaf development for up to 10 hybrids in five experiments for 4 yr. It also compares calculated versus measured soil temperatures in 1 yr. Thermal time requirements for appearance of leaf tips and collars and for duration of leaf expansion were determined using thermal time equations from the CERES‐Maize model. Thermal time values per leaf were stable within experiments, but varied substantially among years and hybrids. Although the CERES‐Maize model predicts leaf tip appearance moderately well, the rate of leaf development appears to differ among hybrids and may be sensitive to daylength and temperature extremes that are not considered by the model. Improvements are also needed in the model prediction of soil temperature.
Portable Soil Coring System that Minimizes Plot Disturbance
Authors: Prior S. A. , Rogers H. H. 
Published: July 2010

AbstractReliable sampling of belowground components is an essential aspect of agro‐ecosystems research. Nevertheless, small plot size, limited access, and remote locations can severely restrict such efforts. To overcome these constraints a light weight, field portable soil coring system was designed. The two‐part unit causes virtually no plot disturbance and, in repeated field tests, performed efficiently and reliably. Soil cores greater than 1 m in length and 38 mm in diameter can be taken. The unit uses a pneumatic driver, an electric core extractor, and steel core tubes with clear plastic liners. As many as 24 cores per hour can be collected with this system. The coring system has been found to be ideal for small size plots or where study areas are enclosed.
Estimating Leaf Area of Pearl Millet from Linear Measurements
Authors: Persaud N. , Gandah M. , Ouattara M. , Mokete N. 
Published: July 2010

AbstractPlant leaf area is a useful observation in physiological and agronomic research. Statistical regression and correlation models have been used to estimate leaf blade area from leaf blade dimensions such as length and width. The objective of this study was to determine if consistent relationships exist among leaf area (A), length (l), and maximum width (m) of pearl millet [ Pennisetum glaucum (L.) R. Br.] leaves from different plant positions and different stages of maturity. Measurements of length, width, and area were made on leaf blades sampled from different positions on pearl millet plants at the 7‐ and 10‐leaf growth stages. Relationships for the model A = klm were derived by least squares regression for these leaves of each position on the plants (where k is an empirical constant). The results of these analyses justified the use of the model A = klm for pearl millet leaves. However, different coefficients may need to be calculated depending on leaf position and growth stage of the plants. This approach could also be applied for other cereal crops whose leaves have similar morphology and anatomy.
Forage and Tuber Yields and Digestibility of Selected Wild and Cultivated Genotypes of Jerusalem Artichoke
Authors: Seiler Gerald J. 
Published: July 2010

AbstractJerusalem artichoke (Helianthus tuberosus L.), a perennial forb, has the potential to be utilized as a silage or tuber crop, but little is known about the variability for forage and tuber yields of wild and cultivated genotypes. Four wild and six cultivated genotypes were evaluated for forage and tuber yields, biomass allocation, and in vitro digestible dry matter (IVDDM) concentrations of stems, leaves, tubers, and whole plants (all above‐ground biomass) at different stages of plant development and compared to an annual commercial oilseed sunflower (H. annuus L.) ‘Hybrid 894’. The perennial genotypes were maintained as pure stands while the annual Hybrid 894 was replanted each year. The cultivated Jerusalem artichoke ‘Sunchoke’ had the highest forage yield (6.3 Mg ha−2) which is comparable to some common forage species. The cultivated genotypes also had the highest mean tuber yield (7.19 Mg ha−1). At maturity, the allocation of biomass for Jerusalem artichoke was 68, 23, and 9% for stems, leaves, and heads, respectively. At flowering, the whole‐plant concentration of IVDDM was above the accepted level (598 g kg−1) for adequate animal nutrition for all genotypes except wild ‘Iowa’, wild ‘Texas’, and cultivated Sunchoke. The sunflower Hybrid 894 had higher IVDDM concentrations than the Jerusalem artichoke genotypes. The significant negative correlation between forage yield and IVDDM concentration indicates that these characteristics cannot be simultaneously improved in a breeding program. There appeared to be enough variability to select for increased forage or tuber yields in Jerusalem artichoke.
Nitrogen Effects on Boll Production of Field‐Grown Cotton
Authors: Boquet D. J. , Moser E. B. , Breitenbeck G. A. 
Published: July 2010

AbstractNitrogen is an essential nutrient for cotton (Gossypium hirsutum L.) that affects plant growth, fruiting, and yield. This study was conducted to determine N effects on the development of harvestable bolls (HB) at fruiting sites among reproductive branches (sympodia). Field experiments were conducted from 1987 through 1990 on Commerce silt loam (fine‐silty, mixed, thermic, nonacid, aeric Fluvaquent) to evaluate responses to preplant N rates of 0, 28, 56, 84, 112, 140, and 168 kg ha−1, and to split applications of 56 + 56 kg N ha−1. Increasing N decreased HB production at Sympodia 5 through 10, and increased HB at Sympodia 12 through 25. At Sympodia 5 through 10, production of HB at Fruiting Site 1 (first position on sympodial branch) decreased from 49% of fruiting sites at the 0 N rate, to 36% of fruiting sites, with N fertilization of 168 kg ha−1. Harvestable boll production at Sympodia 11 through 16 increased from 58% at 0 N up to a maximum of 69% at 84 kg N ha−1. At Sympodia 17 through 25, fruiting sites developing HB increased from 9% up to a mximum of 28% with application of 140 kg N ha−1. Whole‐plant HB development at Fruiting Sites 1, 2, and 3 was optimized at 42, 23, and 8%, respectively, by N rates between 56 and 84 kg N ha−1. Averaged over all fruiting sites, maximum whole‐plant HB development of 24% was obtained with 84 kg N ha−1. Results demonstrate that increased N increased the total number of HB per plant. Increase in yield potential in response to N was limited, however, by decrease in HB at lower sympodia as N was increased, and by the inability of plants to more effectively develop bolls at Fruiting Site 2 and 3, and those at upper sympodia.
Tillage and Residue Effects on Infiltration into Soils Cropped to Cotton
Authors: Baumhardt R. L. , Keeling J. W. , Wendt C. W. 
Published: July 2010

AbstractGreater infiltration of precipitation increases water available for cotton (Gossypium hirsutum L.), wheat (Triticum aestivum L.), and sorghum [Sorghum bicolor L. (Moench)] production on the semiarid Texas South Plains. The objective of this study was to determine the short‐term effects of tillage and crop residues on water infiltration into an Olton clay loam (fine, mixed, thermic Aridic Paleustoll), a Pullman clay loam (fine, mixed, thermic Torrertic Paleustoll), and an Amarillo loamy fine sand (fine‐loamy, mixed, thermic Aridic Paleustalf). Cropping treatments included (i) conventional tillage of continuous cotton (CVT), (ii) no‐tillage, limited residue, of continuous cotton (C‐NTL), and (iii) no‐tillage of cotton grown in rotation with limited grain sorghum (S‐NTL), or (iv) wheat (W‐NTL) residues. Final infiltration rate (IR) and cumulative infiltration (CI) was measured on three soils during three successive years after applying well water at 80 mm h−1 for 1 h with a rotating disk‐type rainfall simulator. Cumulative infiltration varied between 40 and 60 mm and did not increase with increasing sand content among the three soils tested. Compared to CVT, neither W‐NTL nor S‐NTL resulted in significantly greater infiltration. Except on the Pullman soil, C‐NTL consistently had the lowest CI; however, its infiltration tended to increase with time to a level similar to the other rotations of reduced till crops. Results shown that infiltration into these soils at mid‐growing season was not affected by no‐tillage management of limited crop residues.
Spatial Nature of Randomization and Its Effect on the Outcome of Field Experiments
Authors: van Es H. M. , van Es C. L. 
Published: July 2010

AbstractMany sites used for field trials exhibit a spatially‐dependent variance structure in that nearby observations are autocorrelated. This may affect treatment comparisons made at unequal distances. This study investigated (i) the probabilistic nature of randomization with respect to spatial distances in randomized complete block (RCB) designs and (ii) the effect of spatially unbalanced designs on the outcome of field experiments. The mean distance of treatment comparison increases linearly with the number of treatments in the experiment. The lack of spatial balance also increases and is inversely related to the number of replications. This may result in increases in Type II errors for short‐distance treatment contrasts and increases in Type I errors for long‐distance contrasts. Evaluation of two experimental RCB designs involving four and nine treatments and four replications showed that the randomization process does not ensure spatial balance. Two simulated experiments, each using 50 randomizations based on the Mercer and Hall data showed no adverse effect from spatially unbalanced treatment comparisons if the underlying variance structure is random, but significant effects if spatial autocorrelation is present. Expected variances for long‐distance comparisons (5.6% of all comparisons) were 51% higher than the error term resulting in tests of treatment differences at ɑ = 0.05 to actually be conducted at the 0.09 error level. Alternative design and analysis methods that ensure spatially balanced treatment comparisons are discussed.
Forage Yield, Quality, Compatibility, and Persistence of Warm‐Season Grass—Legume Mixtures
Authors: Posler G. L. , Lenssen A. W. , Fine G. L. 
Published: July 2010

AbstractDevelopment of compatible, persistent, warm‐season grass‐legume mixtures could increase forage yield and quality during summer months. We established a trial to determine forage yield, quality, species compatibility, and persistence of binary mixtures of warm‐season grasses with selected legumes, five of which are native to the central USA. Grass entries were switchgrass (Panicum virgatum L.), sideoats grama (Bouteloua curtipendula Michx.), and indiangrass [Sorghastrum nutans (L.) Nash]. Legume entries were purple prairieclover [Dalea purpurea Vent.; syn. Petalostemon purpureum (Vent.) Rydb.], roundhead lespedeza (Lespedeza capitata Michx.), leadplant (Amorpha canescens Pursh), Illinois bundleflower [Desmanthus illinoensis (Michx.) MacMill., B. Robins. & Fern.], catclaw sensitive brier [Schrankia nuttallii (DC.) Standl.], and cicer milkvetch (Astragalus cicer L.), a cool‐season species. Unfertilized grass plots without legumes also were included. The experiment was on a Haynie very fine sandy loam soil (coarse‐silty, mixed, calcareous, mesic Typic Udifluvents). All mixtures containing purple prairieclover, roundhead lespedeza, Illinois bundleflower, or catclaw sensitive brier yielded more forage than did grasses grown alone or with leadplant, except for pure switchgrass in 1986. All legumes increased the crude protein concentration of forage compared to that of grass‐alone plots, except for leadplant with switchgrass in 1986. Inclusion of catclaw sensitive brier and cicer milkvetch with grasses consistently improved in vitro digestible dry matter concentration (IVDDM), while inclusion of roundhead lespedeza, leadplant, and Illinois bundleflower generally resulted in decreased [VDDM concentration of forage. Purple prairieclover generally did not influence IVDMD of mixtures. Persistence of all legumes was good. Cicer milkvetch was not compatible with these grasses because it developed a thick, dense canopy prior to initiation of growth by these grasses.
Yield Contribution of Apical and Subapical Ears in Prolific and Nonprolific Corn
Authors: Durieux R. P. , Kamprath E. J. , Moll R. H. 
Published: July 2010

AbstractPrevious studies have demonstrated higher corn (Zea mays L.) yield potential for prolific corn hybrids (more than one ear) compared to nonprolific hybrids (one ear). However, little is known about the relative contribution of the second ear to total yield at various N levels. This study compared yield responses to N rates of 56, 140, and 224 kg N ha−1 of prolific Hybrids A (I202 × Mo17) and B (I117 × B73) with responses of nonprolific Hybrid C (Pioneer 3320) at a uniform low plant population density. All three hybrids gave a positive yield response to N applications. The prolific hybrids increased both in apical ear weight and in subapical ear weight and number in response to N rate. Averaged over N rates, Hybrid A yielded 24% and Hybrid C 14% higher than Hybrid B in 1987. In 1988, they yielded 13 and 10% higher than Hybrid B. Yield of single ears of nonprolific hybrid was higher than that of the apical ears in the prolific hybrids. Total potential yield in response to N application appears to be highest in Hybrid A because of second ear formation. Factors contributing to to yield increases from N applications in prolific Hybrid A included, in order of importance, an increase in the number of subapical ears, an increase in apical ear weight, and an increase in the subapical ear weight. Contrary to previous reports, apical and subapical ear weight increased simultaneously, with increasing N rates
Temperature Effects on Pima Cotton Leaf Growth
Authors: Reddy K. R. , Hodges H. F. , McKinion J. M. 
Published: July 2010

AbstractTemperature is a primary environmental factor affecting cotton growth. Information on temperature effects on Pima cotton (Gossypium barbadense L.) growth is limited. The objective of this paper is to provide quantitative estimates of temperature effects on leaf emergence rates, the duration of leaf expansion, and rate of expansion. Pima cotton plants were grown from seed in naturally lit controlled environments with unlimited water and nutrients under five day/night temperature regimes ranging from 20/12 to 40/32 °C. Weighted average daily temperature was calculated from 900‐s average temperatures. Carbon dioxide was maintained at 350 µL L−1 during the daylight hours. Leaf area expansion and biomass accumulation were monitored from emergence to 64 d after emergence. Leaf initiation took about 2 d longer for prefruiting nodes at near optimum temperatures than for leaves formed after square initiation. Fruiting leaf initiation required about 4.5 d leaf−1 at 20 °C and about 2.5 d leaf−1 at 30 °C. Leaves expanded in excess of three times more rapidly at 31.3 °C than at 18.9 °C. The optimum temperature for leaf expansion was 31.3 °C. Leaf growth at 35.5 °C was only approximately 60% of that at 31.3 °C. Leaves required about 40% longer to expand at 18.9 °C than at 31.3 °C. All leaves required the same length of time to expand when grown at the same temperature, regardless of position on the mainstem. Since leaves varied greatly in mature leaf size, depending on leaf position, rates of expansion also varied similarly. Maximum leaf growth rates occurred during the 28‐to‐64‐days‐after‐emergence period compared with earlier growth periods, apparently reflecting greater light interception during that period. Biomass accumulation and growth rates were very temperature sensitive and closely related to leaf growth.