bluuebunny/crossref_metadata_2025_split huggingface dataset:
Barley Tiller Response to Plant Density and Ethephon
Authors: Lauer Joseph G. 
Published: July 2010

AbstractEthephon ([2‐chloroethyl] phosphonic acid), typically increases barley (Hordeum vulgare L.) spikes per square meter by increasing the frequency of late emerging green tillers, resulting in uneven crop maturity. This study was conducted to evaluate barley tiller grain yield and malting quality response to plant density and ethephon, with special reference to late‐emerging green tillers. Field studies were conducted at Powell, WY between 1987 and 1989 on a Garland clay loam (fine, mixed, mesic Typic Haplargid). Target plant densities of 150 and 300 plants m−2 were established. Ethephon was applied at the Zadoks growth stages (ZGS) of 13, 32, or 39, and one treatment was split‐applied at ZGS 32 and 39. Early emerging primary tillers (Tl, T2, and T3) and the main shoot contributed 86% of the total grain yield at high plant density vs. 73% at low plant density. In general, increasing plant density resulted in progressively greater differences for kernel plumpness and kernels per spike on the MS, Tl, T2, and T3. Ethephon applied at ZGS 39 reduced plant height 6 to 15 cm depending on year. Lodging was reduced by ethephon application, although the lodging level was low in every year of the study. Ethephon did not affect grain yield or protein content, but it often reduced volume mass and kernel plumpness compared to the untreated control. Regardless of ethephon treatment, kernels on late emerging tillers were of lower mass, volume mass, and plumpness than kernels on early emerging tillers. Ethephon applied at ZGS 39 increased the number of late emerging green tillers by 225 spikes m−2 compared with the control. These late emerging green tillers contributed 8% to the total grain yield but produced grain of substandard malting quality.
Resource Use and Plant Interactions in a Rice‐Mungbean Intercrop
Authors: Aggarwal P.K. , Garrity D.P. , Liboon S.P. , Morris R.A. 
Published: July 2010

AbstractIntercropping of upland rice (Oryza sativa L.) with short‐duration grain legumes has shown promising productivity and resource use efficiency. To better understand intercrop relationships, we used aboveand underground partitions, residue removal, and plant removal to investigate the interactions between upland rice (120‐d crop duration) and mungbean [Vigna radiata (L) Wilczek, 65‐d crop duration]. Treatments were evaluated during two rainy seasons on an unfertilized Typic Tropudalf at Los Baños, Philippines. Nitrogen uptake by intercropped rice (33.4 and 41.1 kg N ha−1) approximated that of sole rice (35.4 and 38.1 kg N ha−1). Intercropped rice yielded 73 to 87% of sole rice and intercropped mungbeans yielded 59 to 99% of sole mungbean. Root barriers did not affect rice N uptake or dry matter accumulation prior to the maturity of the mungbean, but reduced N uptake, dry matter, and grain yields substantially by the time of rice harvest. Sole rice with every third row removed at mungbean harvest had N, grain, and dry matter yields similar to the intercropped rice with every third row occupied by the legume. Sole rice with every third row vacant during the entire growing season yielded similarly (2.6 Mg h−1) to sole rice (2.3 Mg h−1) and intercropped rice (2.0 Mg h−1). There was no evidence that N transfer from the legume to the rice increased N availability to rice above that expected with a sole rice crop with the same planting scheme. Rice yield compensation in the intercrop was apparently due to the increased soil volume for N extraction and increased aerial space available after mungbean harvest.
Peanut Root Response to Drought Stress
Authors: Meisner C. A. , Karnok K. J. 
Published: July 2010

AbstractKnowledge concerning the response of peanut [Arachis hypogaea (L.)] root growth during stress and to irrigation after stress is limited. This study was conducted to determine the effect of timing of water stress imposition on peanut root growth, reproductive development, and pod yield. Root growth was measured weekly using nondestructive methods in rhizotron chambers containing a 4:1 mixture of sand and fritted (calcified) clay. A portable rain shelter was used to impose 30‐d stress treatments beginning at 20, 50, 80, and 110 d after planting (DAP), in addition to a well‐watered control. Root growth was significantly reduced in the upper 40‐cm depth during stress from 20 to 50 DAP compared to root growth during the same period of the wellwatered control. No other stress periods resulted in significantly altered root growth compared to the control. Root growth was not affected in the lower depths of this treatment by stress because of adequate soil moisture. Upon rewatering, there was a trend for root growth to recover and continue further into the season for the two stress treatments beginning at 20 and 50 DAP. By the end of the season, there were no differences in overall average root growth among treatments. Peanut root growth may be temporarily reduced during early stress but appears to recover once rewatered. Pod yields were reduced, 49 and 37%, compared with the control by stress imposed at 50 and 80 DAP, respectively. Thus, adequate moisture during 50 to 80 and 80 to 110 DAP is critical for obtaining maximum yields.
Scanning Electron Microscopy for Studying Root Morphology and Anatomy in Alfalfa Autotoxicity
Authors: Hegde Ramesh S. , Miller D. A. 
Published: July 2010

AbstractThe aqueous extract of alfalfa (Medicago sativa L.) shoots inhibits root elongation, shoot elongation, and/or germination of alfalfa itself‐a phenomenon termed autotoxicity. The study of the mode of action of allelopathic and/or autotoxic compounds at the plant organ and cellular levels is limited by the depth of field, resolution, and magnification of a light microscope compared to a scanning electron microscope. Scanning electron microscopy techniques were used to study the morphology and anatomy of the roots inhibited by the water‐extract of alfalfa shoots. Investigations on the morphology of shoot‐aqueous‐extract‐inhibited, 5‐d old ‘WL‐316’ alfalfa roots revealed a 46% reduction in density and 54% reduction in length of root hairs compared to the control. Anatomical differences between the inhibited and uninhibited alfalfa roots were also observed. Shoot aqueous extract did not cause clogging of xylem vessels. The scanning electron microscope is a valuable tool in the study of the mode of action of allelopathic or autotoxic compounds at the plant organ as well as cellular levels.
Genotype‐by‐Tillage Interactions in Hard Red Winter Wheat Quality Evaluation
Authors: Cox D. J. , Shelton D. R. 
Published: July 2010

AbstractWinter wheat (Triticum aestivum L.) is grown under both conventional‐till and conservation‐till systems in the Northern Great Plains. A benefit of sowing winter wheat into standing stubble is the protection the crop receives from trapped snow and the resultant reduction in winter kill. A 5‐yr study was conducted at four locations in North Dakota to measure cultivar‐by‐tillage interactions for quality parameters of wheat and to determine whether testing under both conventional‐till and no‐till systems was advantageous. Fourteen hard red winter wheat cultivars were planted during 1984‐1985 through 1988‐1989 in a Max loam (fine‐loamy, mixed, Typic Haploborolls) at both Williston and Minot, in a Svea loam (fine‐loamy, mixed, Pachic Udic Haploborolls) at Langdon, and in a Bearden silty clay (fine‐silty, frigid, Aeric Calciaquolls) or Gardena silty loam (coarse‐silty, mixed, Pachic Udic Haploborolls) at Fargo. Significant cultivar‐by‐tillage interactions (P < 0.05 or P < 0.01) were obtained for volume weight, protein content, and flour yield when the analysis was restricted to environments in which wheat winter killed. A change in rank order of cultivars was detected only for volume weight. For the other quality parameters measured, evaluation of winter wheats grown in conventional‐till and no‐till plots resulted in similar relative performance of cultivars.
Efficiency, Competitiveness, and Persistency of Chinese Rhizobium fredii in Iowa Soils
Authors: Manjanatha M.G. , Loynachan T.E. , Atherly A.G. 
Published: July 2010

AbstractNative Bradyrhizobium japonicum occupy the majority of Midwest soybean [Glycine max (L.) Merr.] nodules despite inoculation with more effective N2‐fixing bradyrhizobia. The objective of this study was to determine whether three fast‐growing strains of Rhizobium fiedee obtained from soybean fields in China could displace the highly competitive native strains from the nodules of commonly grown Iowa‐soybean cultivars. Before introducing these nonnative organisms into Iowa soils, we evaluated their effectiveness under greenhouse conditions compared with the effectiveness of B. japonicum strains USDA 110 and USDA 123. There was a dominant strain‐by‐cultivar interaction, and two of the three fast‐growers were as effective in N2 fixation as was USDA 123, but were less effective than was USDA 110. Furthermore, we evaluated the competitiveness of the fast‐growers against native bradyrhizobia in six different soils in the greenhouse. Nodule occupancy by the fast‐growers ranged from 1.5 to 38.7%. Results indicated significant cultivar‐by‐soil, strain‐by‐soil, and soil‐by‐strain‐by‐cultivar interactions. For field tests, two separate sites were selected each year in the summers of 1987 and 1988. Each of the three strains was introduced into soils at approximately 106 colony forming units (CFU) cm−1 row. Nodule occupancies for the four site years on Corsoy 79 and Williams 82 soybean cultivars ranged from 3.8 to 13.3%. The saprophytic survivability of fast‐growers, based on nodule occupancy of field‐collected soil in the greenhouse, was tested 2 and 3 yr after inoculation. Fast‐growing rhizobia isolated from nodules were identified by their acid production on an artificial medium, and the reliability of this method was verified by comparing restriction‐endonuclease‐digestion patterns of plasmid DNA of test and reference strains. The nodule occupancies by strains of R. fredii on Williams 82 ranged from 8.6 to 13.3% and 4.4 to 11.3%, 2 and 3 yr after inoculation, respectively. Thus, the strains of R. fredii were able to persist in soil reasonably well as saprophytes.
Corn Growth Following Cover Crops: Influence of Cereal Cultivar, Cereal Removal, and Nitrogen Rate
Authors: Tollenaar M. , Mihajlovic M. , Vyn T. J. 
Published: July 2010

AbstractRye (Secale cereale L.) cover crops often delay development and reduce yield of corn (Zea mays L.). A 3‐yr study (1982‐1984) conducted to investigate the influence of four rye cultivars and one wheat (Triticum aestivum L.) cultivar, rate of N application in the spring, and removal of above‐ground cereal phytomass on growth and development of corn. Experiments were carried out at the Elora Research Station, Ontario, in a split‐plot design, with two N levels (145 and 220 kg ha‐1) and five cereal cultivars as main plots, and cereal phytomass removal or retention as sub‐plots. Cereal cultivars were planted in September after corn harvest and corn was planted in the spring. Corn leaf number and height were monitored during early corn development and whole‐plant dry matter and moisture of corn were measured in September. The response of corn dry matter accumulation to cereal cover crop cultivar, N rate, and above‐ground cereal phytomass varied among the 3 yr the study was conducted. Cereal phytomass was largest in 1983 and the impact of the cereal cover crop on corn growth and development was largest during this year. In contrast, the impact of cereal cultivar on corn was not associated with phytomass production among the five cereal cultivars. The effects of cereal cultivar cover crop on corn growth and development were largest for the rye cu|tivar Kodiak and the wheat cultivar Gordon, but these cultivars ranked third and fifth, respectively, in above‐ground phytomass production in the spring. Increased N application could partially overcome the reduction in corn growth and development due to the cereal cultivars Kodiak and Gordon, but this was not the case for the other cereal cultivars. Removal of above‐ground cereal phytomass before corn planting generally did not influence the delay in development and reduction in yield of the subsequent corn crop. In conclusion, the reduction in corn dry matter accumulation in response to cereal cover crops is a complex phenomenon, involving quantity of cereal residue, cereal cultivar and, occasionally, N application.
Cation and Nitrate Leaching in an Oxisol of the Brazilian Amazon
Authors: Cahn M. D. , Bouldin D. R. , Cravo M. S. , Bowen W. T. 
Published: July 2010

AbstractHigh rates of N fertilizers are often necessary to achieve yield goals in the humid tropics, where subsoil acidity prevents deep crop rooting. However, leaching of fertilizer nitrate may accelerate the leaching of bases from the crop rooting zone, leading to an acidification of the topsoil and a reduction in crop yields. Our ojective was to investigate the influence of urea and legume green manure sources of N on crop yields, leaching of cations, and the fertility of the plow layer of a clayey Oxisol (Typic Acrudox) of the central Amazon basin. We established a split‐plot field experiment near Manaus, Brazil where main plots received 2 levels of lime (0 and 4 Mt/ha CaCO3) and sub‐plots were cropped with (i) a legume green manure (Canavalia ensiformes L. or Mucuna aterrima L.) followed by maize (Zea mays L.); (ii) maize receiving 300 kg ha−1 of urea‐N, or (iii) left bare‐fallow with an application of 300 kg ha−1 of urea‐N. Plots were periodically sampled to 1.2 m during three cropping seasons. The field site received 4265 mm of rain during the experiment (16 mo). Legume crops accumulated between 142 and 280 kg ha−1 of N. The distribution of NO3 in the soil profile changed in a pattern consistent with leaching. All treatments lost Ca and Mg from the plow layer during the experimental period. Losses were greatest (500–1000 kg ha−1 for Ca and 50 kg ha−1 for Mg) in plots treated with urea and lime. Leaching of bases and the generation of acidity decreased base saturation in the plow layer of all treatments, but was minimized in plots receiving legume green manure N, perhaps because less inorganic N was applied and/or the legume crops recycled leached bases. Unlimed plots receiving urea, had the highest increase in acidity in the 0 to 30‐cm layer and a corresponding 44% reduction in grain yield between the first and third maize crops.
Forage Quality, Mineral Constituents, and Performance of Beef Yearlings Grazing Two Crested Wheatgrasses
Authors: Vogel K. P. , Gabrielsen B. C. , Ward J. K. , Anderson B. E. , Mayland H. F. , Masters R. A. 
Published: July 2010

AbstractIn the central Great Plains, crested wheatgrasses [Agropyron cristatum (L.) Gaetner and A. desertorium (Fischer ex Link) Schultes] are best utilized for early spring and late fall grazing. The principal objective of this study was to determine if beef (Bos taurus L.) yearlings grazing ‘Ruff’ (A. cristatum) during the spring grazing season had higher average daily gains and gains per hectare than cattle grazing ‘Nordan’ (A. desertorum). These cultivars were evaluated in grazing trials (four replications) in eastern Nebraska in 1985, 1986, and 1987. The 0.8‐ha pastures were seeded in the fall of 1983 on a Typic Argiudoll soil and were fertilized annually with 68 to 90 kg N ha−1. Grazing was for 6 wk each spring by yearling steers with a beginning average weight of 250 kg. Averaged over 3 yr, Ruff produced higher gains per hectare than Nordan (272 vs 245 kg ha−1) probably because it produced more herbage because of its better persistence. At the end of the trial, the averge basal cover of Ruff and Nordan were 21 and 6%, respectively. Three‐year mean average daily gains were Ruff = 1.28 vs. Nordan = 1.34 kg d−1, which were unexpected, because Ruff generally had higher forage quality as measured by an array of parameters. Ruff forage had a higher, less desirable grass tetany ratio [K/(Mg+Ca)] than Nordan (2.6 vs. 2.3) averaged over 3 yr. Cattle grazing Ruff had lower blood serum Mg levels than rattle grazing Nordan (15.4 vs. 16.2 mg −1, both of which were below the hypomagnesemia threshold of 18 mg L−1. This condition may have reduced intake and animal gains. These results indicate the need for evaluating pasture and range grass cultivars under grazing conditions.
Monoculture and Rotation System Effects on Precipitation Use Efficiency of Corn
Authors: Varvel Gary E. 
Published: July 2010

AbstractDevelopment and utilization of cropping systems in rainfed areas are highly dependent on their water use efficiencies, especially in subhumid areas. The objective was to evaluate the effect of crop rotation and N fertilizer rates on precipitation use efficiency by dryland corn (Zea mays L.). Corn was grown under rainfed conditions at Mead, NE, on a Sharpsburg silty clay loam (fine, montmorillonitic, mesic Typic Argiudoll) in four cropping systems: (i) continuous corn, (ii) a 2‐yr soybean [Glycine max (L.) Merr.]‐corn rotation, (iii) a 4‐yr rotation of oat [Avena sativa (L.)] + clover [80% Melilotus officinalis Lam. and 20% Trifolium pratense L.]‐grain sorghum [Sorghum bicolor (L.) Moench]‐soybean‐corn, and (iv) a 4‐yr rotation of soybean‐grain sorghum‐oat + clover‐corn. Nitrogen fertilizer rates used for corn were 0, 90, and 180 kg N ha−1 as NH4NO3. Corn grain precipitation use efficiency was significantly affected by year, rotation, and N fertilizer rates from 1984 through 1991. Precipitation use efficiency ranged from 36 to 137 kg ha−1 cm−1 for continuous corn and from 57 to 165 kg ha−1 cm−1 for corn grown in rotation from 1984 through 1991. Precipitation use efficiency was greater in rotation (101.8 kg ha−1 cm−1) than in continuous corn (83.6 kg ha−1 cm−1). In dryland production areas, cropping systems with greater and more stable precipitation use efficiency can reduce crop failures.
Sorghum Germination and Development as Influenced by Soil Temperature and Water Content
Authors: Anda A. , Pinter L. 
Published: July 2010

AbstractIn Hungary, the seed‐bed temperature at the customary planting time for sorghum [Sorghum bicolor (L.) Moench] is typically close to the base temperature, 10°C (the temperature at which there is zero development). At low soil temperatures, soil water may also be critical. This 30‐d phytotron study examined the combined effect of low soil temperature at two soil water levels on sorghum emergence and early development. Ten initial soil temperatures (7–16°C) and two soil water treatments (high and low: −0.04 and −0.2 MPa water pressure, respectively) were used. Since, after 19 d (5–24 June), there was no emergence at soil temperatures below 9°C, soil temperature in all pots was increased to 20°C and was maintained at this level until the end of experiment on 5 July. Percent emergence increased with increasing initial soil temperatures. The slope of this curve was four times steeper with −0.04 than −0.2 MPa water pressure. The improved microclimatic conditions caused by higher initial soil temperatures led to faster emergence, which may have produced better sorghum seedling establishment. Although seeds sown in soil with alternating low (below base temperature) and high seed‐bed temperatures can emerge, quick emergence and adequate plant density is less likely. In Hungary, where both air and seed‐bed soil temperatures vary a great deal around sorghum planting time, it is better to wait until the upper soil temperature stabilizes above 10°C, the base temperature for sorghum.
A Novel Method to Monitor Root Decomposition Demonstrates that Salt Stress Can Enhance the Rate of Tomato Root Decomposition
Authors: Snapp Sieglinde S. 
Published: July 2010

AbstractThis study quantified the effects of an abiotic stress, salinity, and a biotic stress, phytophthora root rot, on root mortality and decomposition in tomato (Lycopersicon esculentum Mill.). Rhizotron windows were used to measure root mortality rates in mature, container‐grown plants. A novel assay was developed to monitor root decomposition by quantifying root‐length disappearance over time using petri dishes in incubation chambers. Phytophthora root rot infection was induced by salt stress in the presence of Phytophthora parasitica Dastur inoculum; however, the moderate levels of disease induced had no effect on rates of root mortality or on root decomposition. Genotypic differences in root decomposition under salt stress were shown by the decomposition assay, the first report of intraspecific variation in root decomposition rates. High‐salt UC82B had 50% higher root mortality and a threefold higher initial root decomposition rate than low‐salt UC82B. In contrast, salinity did not enhance root mortality or decomposition in cv. CX8303. UC82B grown under salt stress had thin roots of high N concentration, whereas salt stress did not alter N concentration in CX8303 roots. On a plant by plant basis, root N concentration was correlated with initial rootlength loss in the degradation assay, whereas root diameter was not. The results indicate that an indirect consequence of salt stress could include rapid root decomposition.
Performance Comparisons of Conventional and Laboratory‐Scale Alfalfa Hay Bales in Isolated Environments
Authors: Coblentz Wayne K. , Fritz John O. , Bolsen Keith K. 
Published: July 2010

AbstractNegative quality changes, including Maillard reaction damage, in alfalfa (Medicago sativa L.) hay frequently are associated with spontaneous heating resulting from packaging and storing forage at moisture levels in excess of 200 g kg−1. Forage at three moisture levels (268, 229, and 185 g kg−1) was packaged in laboratory‐scale bales at 1.0, 1.3, 1.7, and 2.0 times the density of parent, conventional bales and subsequently incubated in two different isolated environments such that all measured heat accumulation was the result of self‐generated heat. Laboratory scale hay packages generated measurable heat and exhibited quality changes when incubated (i) between straw bales stacked in an open‐air pole shed and (ii) in insulated incubator boxes in a storeroom where the minimum ambient storage temperature was set at at 25°C. Heat development and negative quality changes were greater in the box‐incubation system, indicating a need to control ambient storage temperature. At the high and medium moisture levels, acid‐detergent insoluble N (ADIN) fractions for high‐density, box‐incubated laboratory bales were at least similar (P = 0.05) to those of parent, conventional bales, despite large disadvantages in measures of accumulated heat. These responses in laboratory bales were consistent with those reported in previous haystack‐incubated studies and suggest that the environmental heat component created by adjacent conventional bales in those studies may have had a limited direct effect on ADIN content. Increasing density of laboratory bales probably rendered alfalfa proteins more susceptible to Maillard reaction damage and/or allowed the reaction to proceed more efficiently with respect to self‐generated heat than it did in conventional bales.