bluuebunny/crossref_metadata_2025_split huggingface dataset:
Matric Priming Increases Germination Rate of Great Basin Native Perennial Grasses
Authors: Hardegree Stuart P. 
Published: July 2010

AbstractCheatgrass (Bromus tectorum L.) is an undesirable nonnative annual that germinates at relatively low temperatures in the spring and fall and can establish a root system more quickly than Great Basin native perennial grasses. The purpose of this study was to determine whether seed priming could be used to enhance low‐temperature germination rate of native perennial grasses so that they can better compete with cheatgrass. A matric‐priming technique was used to increase low‐temperature germination rate of seven native perennial grasses: blue‐bunch wheatgrass [Pseudoroegneria spicata (Pursh) Löve], thickspike wheatgrass [Elymus lanceolatus (Scribn. & J.G. Smith) Gould; syn. Agropyron dasystachyum (Hook.) Scribn.], basin wildrye [Leymus cinereus (Scribn. and Merr.) A. Löve], sheep fescue (Festuca ovina L.), canby bluegrass (Poa canbyi Scribn.), sandberg bluegrass (Poa sandbergii Vasey), and bottlebrush squirreltail [Sitanion hystrix (Nutt.) J.G. Smith]. Seeds primed at both 10 and 25°C were evaluated for germination response at both 10 and 25°C. Days to 50% germination (D50) was ≈ 4 d for cheatgrass germinated at 10°C. Native grass seeds in control treatments germinated between about 4 and 11 d later than cheatgrass at 10°C. Priming reduced D50 by between 4 and 8 d for all native species when germinated at 10°C. Germination rate at 10°C was generally higher when the seeds were primed at 25°C, except for basin wildrye. Priming increased cold temperature germination rate of bluebunch wheatgrass, thickspike wheatgrass, and sheep fescue to a level comparable to cheatgrass.
Grain Sorghum Yield Response to Nonuniform Stand Reductions
Authors: Larson E. J. , Vanderlip R. L. 
Published: July 2010

AbstractNonuniform stand reductions caused by poor emergence, insect damage, or other factors, occur frequently in grain sorghum [Sorghum bicolor (L.) Moench] fields. This research was conducted to determine the effect of within‐row skip patterns on grain yield and yield component compensation, particularly for hybrids differing in tillering ability. Dryland field studies were conducted at Manhattan (Reading silt loam, fine‐silty, mixed, mesic Typic Argiudoll) and St. John (Naron fine sandy loam, fine‐loamy, mixed, thermic Udic Argiustoll), KS, during 1988 and 1989. Two medium‐maturity hybrids, DeKalb DK‐46 and Pioneer 8500, were selected based on low and high tillering ability. Plots were three rows, with the middle row containing a within‐row skip pattern. Results were analyzed separately by skip row, adjacent row, and average for the three rows. Skip lengths within a 7.6‐m row were 0.9 m, 0.9 m repeated three times, and 2.7 m within the skip row, and the 0.9 m × 3 pattern in all three rows. Yield of the skip row was reduced by every configuration bordered by control stand adjacent rows. Yield compensation from adjacent rows and within the skip row compensated for reduced stands, except for a 2.7−m skip resulting in 5.1% yield reduction, 64% uniformly spaced stand in all three rows with 6.9% yield reduction, and three 0.9 m within‐row skips in all three rows with 10.9% yield reduction. Compensation was primarily in number of heads per plant and seeds per head. Difference in hybrid tillering response did not influence grain yield. Thus, yield reduction is likely only where skips result in severe plant spacing nonuniformity.
Plant Development, Water Relations, and Carbon Allocation of Heart‐Podded Hoary Cress
Authors: Miller Richard F. , Svejcar Tony J. , Rose Jeffrey A. , McInnis Michael L. 
Published: July 2010

AbstractAttempts to control the noxious weed heart‐podded hoary cress [Cardaria draba (L.) Desv.] in the Pacific Northwest have been relatively ineffective, and this species has expanded its distribution from irrigated hayland onto adjacent semiarid rangelands. The objective of this study was to define the seasonal pattern of development and biological activity of heart‐podded hoary cress growing on semiarid rangeland. The study was conducted in the field over a 2‐yr period on a terrace site that has deep Cumulic Haploxeroll soil and an adjacent upland site that has a shallow Lithic Argixeroll soil. Soil water content, phenology, xylem pressure potential and leaf conductance were measured at both sites. Aboveand belowground biomass and spring C allocation pattern, determined by labeling plants with 13C, were measured at the terrace location. Regardless of location, no heart‐podded hoary cress seedlings were found; all shoots developed from rhizome buds. The majority (76%) of heartpodded hoary cress biomass was located belowground. Although drought occurred earlier on the upland than the terrace site, phenology was similar on the two sites. Carbon was translocated to belowground tissues within 1 h of labeling and reached peak accumulation within 24 h. The greatest 13C enrichment of roots and rhizomes occurred during the flowering stage. The peak in belowground C allocation occurred at a stage when leaf conductance was declining rapidly. The short period of maximum C allocation to belowground tissue, the large proportion of belowground tissue, and the wide variation of phenology among plants at a given time may account for the difficulty in chemically controlling this species.
Responses of Kura Clover to Sheep Grazing and Clipping: I. Yield and Forage Quality
Authors: Peterson Paul R. , Sheaffer Craig C. , Jordan Robert M. , Christians Charles J. 
Published: July 2010

AbstractFew perennial legumes have dependable long‐term productivity under grazing in the northern USA. Our objective was to determine the effects of frequent clipping and sheep(Ovis spp.) grazing on forage yield and quality of kura clover (Trifolium ambiguum. Bieb.), a rhizomatous perennial legume. Clipping and grazing trials were initiated on a 5‐yr‐old stand of ‘Rhizo’ kura clover on a Waukegan silt loam and conducted for 3 yr. Total season yield (mean of 8.6 Mg ha‐1) was unaffected by clipping frequency until the third year, when five and six cuttings per season produced 80 and 70% as much forage, respectively, as either three or four cuttings. In the second and third years of sheep grazing treatments, kura clover rotationally stocked with 14‐d rest periods produced 28 and 16% less forage, respectively, than that under rotational stocking with 28‐d rest periods. In contrast to total season forage yield, spring yield following 3 yr of clipping and grazing did not differ among clipping frequency increased from three to six cuttings per year, (Missing Data.) (CP) and in vitro digestible dry matter (IVDDM) concentrations increased from 222 to 254 and from 854 to 880 g kg ‘1 DM, respectively, and neutral‐detergent fiber (NDF) concentration decreased from 326 to 295 g kg‐1 DM. Forage was of high quality, because leaf concentration always exceeded 850 g kg‐1 of forage dry matter. Established kura clover is tolerant of frequent and close defoliation and warrants pasture use because of its long‐term productivity and high forage quality.
Growth Characteristics of Rhizoma Peanut and Nitrogen‐Fertilized Bahiagrass Swards
Authors: Williams M. J. 
Published: July 2010

AbstractThe interaction of plant sensitivity to drought with N deficiency has been suggested as the reason grasses fail to persist under grazing when grown in association with rhizoma peanut (Arachis glabrata Benth.). To test this assumption, aboveground dry matter (DM) accumulation and relative growth rate (RGR) of ‘Florigraze‘ rhizoma peanut and ‘Pensacola’ bahiagrass (Paspalum notatum Flügge) fertilized with 0, 56, and 112 kg N ha−1 were measured from March to November in 1990 and 1991. Rhizoma peanut aboveground DM accumulation was greater both years (4950 and 6100 kg ha−1 1990 and 1991, respectively) in July at the start of the summer rainy season than any N‐fertilized bahiagrass treatment (640 and 1530, 1240 and 2330, and 1570 and 4490 kg ha−1 in 1990 and 1991 for 0‐N, 56‐N, and 112‐N treatments, respectively), due to higher RGR. Although the RGR of rhizoma peanut was similar to or less than that of the bahiagrass treatments for the remainder of the growing season in both years, by August 1991 only the 112‐N bahiagrass treatment (5260 kg ha−1) had total DM accumulation similar to rhizoma peanut (5110 kg ha−1). Rhizoma peanut RGR appeared to be more sensitive to rainfall, and was positively correlated (r = 0.71) with rainfall for as long as 8 wk prior to the sample dates in the dry spring of 1990. Bahiagrass RGR showed no correlation with rainfall either year. This suggests that lack of persistence of bahiagrass in mixed swards is due to severe competition for light with rhizoma peanut in springs when moisture is adequate and to potentially increased stress due to grazing in springs when drought restricts growth of rhizoma peanut.
Evaluation of LEACHM: II. Simulation of Nitrate Leaching from Nitrogen‐Fertilized and Manured Corn
Authors: Jemison John M. , Jabro Jalal D. , Fox Richard H. 
Published: July 2010

AbstractHigh NO3‐N concentrations in groundwater resulting from agricultural production have increased the need for mathematical models to predict the concentration and mass of NO3‐N leached from agricultural soils. Study objectives included evaluating the N version of LEACHM (LEACHMN) to predict mass of NO3‐N leached from nonmanured and manured corn (Zea mays L.), and to test two methods of model validation. Four treatments (no manure with 0 and 200 kg N ha−1 and a manure treatment with 0 and 100 kg N ha−1) from a NO3 leaching experiment were modeled for 1988, 1989, and 1990. Model calibration involved adjusting nitrification, denitrification, and volatilization rate constants to minimize differences between predicted and observed data. When calibrated for each year, LEACHMN produced reasonably accurate predictions of NO3‐N mass leached; however, LEACHMN tended to overestimate summer and underestimate spring leaching losses. The lack of a provision in LEACHM to allow solute diffusion out of water flow channels, and underpredicted corn N uptake early in the season probably created conditions conducive for high leaching losses early; following harvest, insufficient NO3‐N in the soil profile resulted in the model underestimating leaching in the spring. Validating LEACHMN using 1988 rate constants for the 1989 and 1990 years was unsuccessful. When 3‐yr average rate constants were used, simulation accuracy improved somewhat; most accurate simulations were found if 3‐yr average values were close to the calibrated rate constant for that year. The model's predictive capability would probably improve if it contained a more complex corn N uptake routine and a dual‐pore water flow component.
Accumulation and Partitioning of Dry Matter in Water Yam
Authors: Goenaga Ricardo J. , Irizarry Heber 
Published: July 2010

AbstractThere is a scarcity of field‐growth data from which a yam (Dioscorea alata L.) growth model could be developed to promote agrotechnology transfer of the crop in the tropics. A 2‐yr field study was conducted on Corozal soil (clayey mixed isohyperthermic Aquic Tropudults) in an initial effort to collect data on patterns of leaf area development and dry matter accumulation and partitioning among various plant parts during growth and development of yam plants. In the first year of the study, plants of D. alata cv. Gunung were subjected to fertilizer rates of 0, 667, 1333, 2000, and 2667 kg ha−1 of a 15‐2.2‐12.4‐3% (N‐P‐K‐Mg) commercial mixture at 5O d after planting (DAP). Biomass harvests were conducted at 60, 90, 120, 150, 180, and 210 DAP. For all plant parts studied, dry matter content was not significantly affected by fertilizer treatment. Even after excluding application of fertilizer during the second year, there were no statistical differences in total and tuber dry matter content between years. Maximum leaf area index values (LAI ≈ 8) were attained by 140 DAP. During this period, leaves and vines accounted for at least 80% of the total plant dry matter; thereafter, their dry matter content declined. After 140 DAP, increases in total dry matter were the result of rapid increases in tuber dry matter accumulation. The lack of response to fertilizer treatment and high tuber dry matter production suggest that the preplanting soil nutrient status was adequate to support optimum growth of the yam cultivar used during both years of this study, even without the application of fertilizer.
Simulated Hail Damage to Rice: II. Effects during Four Reproductive Growth Stages
Authors: Counce Paul A. , Wells Bobby R. , Norman Richard J. , Leong Jeff 
Published: July 2010

AbstractKnowledge of grain yield responses to simulated hail damage is useful in assessing hail damage, assessing similar types of damage, and better understanding crop biology. In previous experiments, we determined that reproductive stages of rice (Oryza sativa L.) development were most sensitive to damage. Objectives of this study were to delineate grain yield effects of simulated hail damage during critical reproductive growth stages at which various components of yield are set. Field experiments were conducted on a Crowley silt loam soil (fine, montmorillonitic, thermic Typic Albaqualfs) in 1985 and 1986 using the cultivar Lebonnet. At four reproductive growth stages, yield loss was determined from these three treatments: (i) removal of the top 1, 2, and 3 fully expanded leaves, (ii) bending of 10, 20, or 40% of culms, and (iii) severing of 10, 20, or 40% of culms. All three types of damage were significant at some level of intensity at all four growth stages. The largest yield reductions resulted from leaf removal. Leaf removal resulted in the greatest amount of yield reduction at booting and heading, with less damage from leaf removal 14 d after heading and least damage from leaf removal at panicle initiation (PI). Yields were reduced as more leaves were removed. Culm severing caused less yield reduction than leaf removal and the least yield reductions resulted from culm bending. Culm severing was progressively more damaging to yield as the rice developed through the season and reductions were similar to those found for leaf removal at 14 d after heading. Culm bending was found to be significantly damaging to yield except at the 10% treatment levels at heading and 14 d after heading. Despite apparently extreme damage treatments, rice yields were reduced by <15% in response to most of the treatments imposed. Consequently, the rice crop has considerable ability to compensate for physical damage due in part to the unique biology of the rice plant.
Nitrogen Dynamics of Grain Legume–Weedy Fallow–Flooded Rice Sequences in the Tropics
Authors: George Thomas , Ladha Jagdish K. , Garrity Dennis P. , Torres Rolando O. 
Published: July 2010

AbstractDry‐season (DS) grain legume‐weedy fallow‐wet‐season (WS) flooded rice is a common cropping sequence in the rainfed lowlands of tropical Asia. To better manage N in this cropping system, we need to understand N dynamics and balances as influenced by the aerobic‐anaerobic soil aeration sequence, legume cropping, biological N2 fixation (BNF), and recycling of legume residues. To understand N dynamics under a range of N derived from BNF (15N‐estimated), harvested in pods and left in residues, we conducted a 2‐yr experiment on a Philippine Alfisol using cowpea [Vigna unguiculata (L.) Walp.], mungbean [V. radiata (L.) Wilcz.], nodulating and nonnodulating soybean [Glycine max (L.) Merr.], and weeds. The main portion of soil mineral N (0 to 60 cm) was NO3 in the dry season and NH4 in the wet season. The sum of soil NO3 and soil N uptake at legume harvest exceeded the decrease in soil NO3 from legume seeding to harvest by 81 kg ha−1, indicating the continued production and legume uptake of soil NO3. The large differences in total N of legumes (46 to 238 kg N ha−1), however, were associated with differences in N derived from BNF (0 to 176 kg N ha−1). When pod N was excluded, legume N balance was, in most cases, negative. The average soil N depletion was 40 kg ha−1 from nonnodulating soybean, compared with 8 kg ha−1 from N2‐fixing legumes. In terms of WS rice grain and N yields, legume cropping did not differ from weedy fallowing, despite greater (by up to 46 kg N ha−1) quantities of legume residue N in some instances. Large amounts of legume residues, however, were associated with reduced legume grain yields, thus decreasing the harvestable grain N output. Fertilizer N, compared with residue N, had a greater effect on WS rice grain and N yields. The use of legumes in lowland rice‐based cropping systems must maximize harvestable N while effectively using soil, BNF, and applied N sources.
Fractal Description of Temporal Yield Variability of 10 Crops in the United States
Authors: Eghball Bahman , Power James F. 
Published: July 2010

AbstractFractal analysis has been used to characterize both temporal and spatial variability in plant and soil parameters. A plant parameter of prime concern is crop yield. Consequently, the temporal variability of 10 crops commonly grown in the USA was described using fractal analysis. Average yields of nine grain crops along with fiber yield of cotton (Gossypium hirsutum L.) from 1930 to 1990 in the USA were used for semivariogram and fractal analyses. Semivariance was calculated for each crop for different year intervals (h). The slope of the regression line of log semivariance vs. log h for each crop was used to calculate fractal dimension [D = (4 — slope)/2], which is an indication of the pattern of yield variability. A small D‐value (near 1) indicates the dominance of long‐term variation, while a large D‐value (near 2) indicates dominance of short‐term variation and nondominance or lack of long‐term variation or trend. From 1930 to 1990, yield of all crops increased, ranging from about twofold in soybean [Glycine max (L.) Merr.], oat (Avena sativa L.), and barley (Hordeum vulgare L.) to about sixfold in maize (Zea mays L.). Crop improvement through plant breeding and the use of fertilizers and pesticides are presumably the main reasons for increased yield. Large yield differences were observed after 1960 for most of the crops studied, suggesting that risk resulting from year‐to‐year yield differences increased with improved yields. Fractal dimensions ranged from 1.20 to 1.47 for the crops studied, identifying long‐term trend as well as short‐term variation in yield of these crops. Rice (Oryza sativa L.) had the smallest D‐value, indicating that this crop had the least short‐term variation, while oat and soybean had the largest D, indicating greatest short‐term variation. Temporal variability in average crop yield in the USA was much smaller than typical spatial variability values reported by others for soil parameters. It appears that fractal analysis is useful in quantifying temporal variability in yield of various crops and can be applied to agronomic research to characterize temporal variations.
Surface Runoff, Uniformity of Water Distribution, and Yield of Peanut Irrigated with a Moving Sprinkler System
Authors: Ben‐Hur M. , Plaut Z. , Levy G. J. , Agassi M. , Shaiberg I. 
Published: July 2010

AbstractInfluence of water application uniformity of irrigation systems on crop yield has been well documented, but effects of runoff on water distribution in a field and on yield have been less studied. The objective was to determine the effect of runoff on water distribution and peanut (Arachis hypogaea L.) yield in a field irrigated with a lateral moving sprinkler irrigation system (MSIS). The experimental field with silt loam soil (300 by 120 m; 3% slope) was located in the Negev, Israel. The treatments were: (i) microbasins along furrows, where runoff was trapped by the microbasins and penetrated into the soil later, and (ii) the control, where runoff was allowed to move downhill. In each treatment, pod and canopy yields and soil water content were measured at different sites along the slope. Surface runoff from 3−m2 plots in the control treatment was low at the beginning of the growing season and increased to an average of 37.5% in later irrigations. The microbasins increased the uniformity of soil water content along the slope. In control plots, soil water content was higher downhill than uphill because of runoff. Pod and canopy yields in the microbasin treatment were fairly uniform along the slope (CV of 1.3 and 2.8%, respectively). In contrast, pod and canopy yields increased in the downhill direction in control plots (CV of 8.6 and 15.5%, respectively). Preventing runoff improved the distribution uniformity of available water in the field, and increased average pod yield by 880 kg ha−1.
Allelopathic Influence of Nine Forage Grass Extracts on Germination and Seedling Growth of Alfalfa
Authors: Chung Ill‐Min , Miller Darrell A. 
Published: July 2010

AbstractPoor establishment of alfalfa (Medicago sativa L.) often results when the alfalfa is sown with cool‐season perennial grasses. This study was conducted to screen the inhibitory characteristics of grasses that are often grown in combination with alfalfa in grass swards. Laboratory and greenhouse studies were conducted to determine the allelopathic potential of nine grasses to alfalfa germination and seedling growth. Alfalfa seeds were germinated in aqueous extracts of nine grasses, using distilled water as a control. Measurements were taken to determine the effect of the extracts on germination, seedling length, and weight. Alfalfa germination ranged from 64% for tall fescue (Festuca arundinacea Schreb.) extracts to 91% for the control. Total alfalfa seedling length was reduced by 39% for grain sorghum [Sorghum bicolor (L.) Moench] extracts. Dry weights of alfalfa cotyledons, hypocotyls, and radicles were reduced significantly by several grass extracts. Smooth bromegrass (Bromus inermis Leyss.), orchardgrass (Dactylis glomerata L.), and grain sorghum extracts were more inhibitory than other grass extracts. Alfalfa seedling emergence and survival percentage was affected by various grass root residues. Timothy (Phleum pratense L.) extracts caused the lowest survival percentage of 59% compared to the control of 88%. Redtop [Agrostis gigantea Roth; syn. Agrostis alba L. sensu auct. (American)] and reed canarygrass (Phalaris arundinacea L.) extracts had no effect on alfalfa seedling emergence and survival. Leached and nonleached residues significantly inhibited alfalfa height, leaf area, and dry weights of leaves and stems. The extent of reduction was greater in nonleached than in leached residues. These results suggest that grass residues may affect alfalfa growth and development because of inhibitory effects of allelochemicals present in grass residues.