bluuebunny/crossref_metadata_2025_split huggingface dataset:
Root Initiation and Root and Leaf Elongation of Dependent Little Bluestem Tillers Following Defoliation1
Authors: Carman J. G. , Briske D. D. 
Published: July 2010

AbstractNewly initiated tillers must survive for a period of time without an established root system and, therefore, are dependent on the parent‐ shoot for water and nutrients. Little is known about the influence of defoliation on subsequent root initiation and root and leaf elongation in dependent tillers. This investigation, conducted in a controlled environment, was designed to 1) determine the leaf stage at which dependent little bluestem [Schizachyrium scoparium (Michx.) Nash var. frequens R. T. Hubb.] tillers are capable of initiating adventitious roots and 2) compare the influence of two intensities of differential defoliation on root initiation and root and leaf elongation of dependent little bluestem tillers. Treatments included defoliation of the dependent tiller, defoliation of the parent‐shoot and defoliation of all plant shoots except for the dependent tiller, to a 3 or 5 cm stubble height.Adventitious root intiation of dependent little bluestem tillers seldom occurred prior to the fourth leaf stage. Defoliation of only the dependent tiller did not significantly (P ≤ 0.05) decrease the number of adventitious roots initiated or suppress mean root length of dependent tillers in comparison with untreated plants. Defoliation of either the parent‐shoot or all plant shoots suppressed root initiation and root elongation of dependent tillers to a much greater extent than did dependent tiller defoliation. Mean root and leaf length of dependent tillers differed between treatments where all plant shoots were defoliated, and where only the parent‐shoot was defoliated. Mean root length of dependent tillers in the former treatments were 62 and 57% of the corresponding length in the latter treatments for the moderate and severe defoliation intensities, respectively. Mean leaf length of dependent tillers in the former treatments were 135 and 147% of the corresponding length in the latter treatments for the moderate and severe defoliation intensities, respectively.Following defoliation of all plant shoots, mean leaf length of dependent tillers was greater than in untreated plants while mean root length was less than in untreated plants. When only parent‐shoots were defoliated, mean root length of dependent tillers was shorter than in untreated plants, while mean leaf length was unaffected. Reduced rates of dependent tiller root elongation following plant defoliation may reduce forage production by preventing successful establishment of newly initiated tillers.
Economic and Agronomic Impacts of Varied Philosophies of Soil Testing1
Authors: Olson R. A. , Frank K. D. , Grabouski P. H. , Rehm G. W. 
Published: July 2010

AbstractPhilosophical differences exist in the interpretation and recommendations made from soil test values acquired by different organizations that provide advice to farmers on fertilizer use. It was the objective of this study to evaluate the economic and agronomic impacts of these varied philosophies with particular reference to concepts of cation ratio, nutrient maintenance, and nutrient sufficiency level. Field experiments were conducted during 1973–1980 on four major soils of Nebraska comparing yields of corn (Zea mays L.) grown with fertilizer treatments as recommended by five soil testing laboratories operating in the state. The 29 field comparisons revealed no real yield differences despite wide variation in number, rate, and cost of nutrients applied. Since soil test levels are increasing or at least holding steady with the “nutrient sufficiency” approach to soil testing, we find no economic or agronomic basis for the “balance” or “maintenance” concepts on these representative soils of the western Corn Belt. Not to be overlooked are environmental implications nor the waste of energy and resources from any approach responsible for excessive fertilizer use. It is recognized that reserves of available nutrients in the deep subsoils and underlying soil‐forming materials in this region have a substantial bearing on soil test calibration and that different calibrations may exist with less favorable subsoil rooting conditions.
Effect of Temperature and Fertilizer N on Apex Development in Spring Wheat1
Authors: Frank A. B. , Bauer A. 
Published: July 2010

AbstractDevelopment of crop growth simulation models has indicated a lack of information on effects of specific environmental factors on growth and yield of hard red spring wheat, Triticum aestivum L. em Thell. One environmentally sensitive yield component is the number of kernels per ear. The objective of this research was to determine effects of temperature and fertilizer N on early plant growth, apex development, and number of spikelets and kernels per ear. ‘Sinton’ spring wheat was grown in a controlled environment chamber at 10, 18, and 26 C with 0, 78, and 224 kg N/ha. Irradiance was 1,000 µEm−2 sec−1 and 16‐hour photoperiod. Duration of the vegetative phase of the apexes was determined for the main stem (M) and the first (T1), second (T2), and third (T3) tillers and duration of the spikelet development phase was measured for M. Tillers and leaves were tagged as they appeared and their development related to apex development. Spikelets and kernels per ear were determined for each stem at maturity.Duration of M apex vegetative phase was influenced by temperature but not by N level; the spikelet development phase was influenced by both temperature and N level. Duration of the vegetative phase was 24, 22, and 17 days at 10, 18, and 26 C, respectively. Duration of the spikelet development phase was significantly shorter at 26 C (4.8 days) than at 10 C (6.5 days) and 18 C (7.4 days). Development of tiller apexes appeared to be strongly synchronized to development of the M apex. Inflorescence initiation on M occurred at the 5.1 leaf stage at 18 C and at 4.4 leaf stage for both the 10 and 26 C treatment.Kernels per ear for the main stem and tillers decreased significantly from 27.2 and 24.8, to 18.5 as temperature increased from 10 to 18 to 26 C, respectively. Fertilizer N levels of 0, 78, and 224 kg N/ha produced kernel numbers of 20.8, 23.5, and 26.2, respectively. Tillers originating at the coleoptile node produced fewer kernels per ear at 10 C than leaf tillers, but not at 18 or 26 C. The percentage of first tillers elongating from the coleoptile node was 62, 47, and 30 at 10, 18, and 26 C, respectively.Results show that early vegetative growth and apex development is more sensitive to temperature than to N fertilization. Kernels per ear for tillers is controlled in part by their synchronization to the development of the M apex.
Analysis and Interpretation of Factors Which Contribute to Efficiency of Nitrogen Utilization1
Authors: Moll R. H. , Kamprath E. J. , Jackson W. A. 
Published: July 2010

AbstractDifferences in N response among corn (Zea mays L.) genotypes reflect variation in numerous processes involved in N use efficiency. In order to facilitate the study of such variation, we develop and demonstrate a concept for evaluating the contribution of N uptake and utilization processes to variation in N use efficiency. Eight hybrids were grown in a replicated field experiment at two levels of N fertilizer on a Dothan loamy sand (Typic Plinthic Paleudult). Differences among the hybrids for components of N use efficiency were evaluated from measurements of grain yield, N accumulation in the plant at silking, and N accumulation in the grain and stover at harvest. Significant differences were found among hybrids and between N levels for all traits. Interactions among hybrids and N levels were significant for all traits except grain yield. At low N supply, differences among hybrids for N use efficiency were due largely to variation in utilization of accumulated N, but with high N they were due largely to variation in uptake efficiency. Variation in proportion of N translocated to grain was also important at the low N supply. Variation in N accumulated after silking was not important at either level of N supply. Variation in N remobilization from vegetative tissue to grain was moderately important at the low N supply. Hybrids with similar levels of N use efficiency showed marked differences in component traits which contribute to efficiency.
Remedial Postemergence Legume Inoculation with Rhizobium1
Authors: Rogers D. D. , Warren R. D. , Chamblee D. S. 
Published: July 2010

AbstractLegume inoculation failures often result in severe stand losses and yield reductions. The objective of this study was to determine the possibility of salvaging poorly nodulated stands of fall‐seeded ‘Arc’ alfalfa (Medicago sativa L.) (fine‐loamy, siliceous, thermic Typic Paleudult soil type) and ‘Viking’ birdsfoot trefoil (Lotus corniculatus L.) (clayey, kaolinitic, thermic Typic Hapludult soil type). Three postemergence soil inoculation techniques were evaluated in the field: a) Subsurface application of inoculum‐coated sand, b) subsurface application of a peat‐base granular inoculant, and c) application of a water‐inoculum suspension as a surface spray. Varying rates of the appropriate Rhizobium strains (Rhizobium meliloti Dang., or Rhizobium sp. of Lotus subgroup) were applied approximately 2, 4, or 8 weeks after seedling emergence. Measurements of nodulation, N concentration, and yield were made.Satisfactory nodulation and plant growth were generally obtained from inoculation treatments made 2 and 4 weeks after plant emergence with all three techniques. Remedial inoculation treatments made in late fall approximately 8 weeks after plant emergence were unsuccessful. Except under low moisture conditions, inoculum application rates ranging from 1.4 to 1.9 kg/ha were sufficient for effective nodulation for techniques a and c. The lowest rates tested for technique b ranged from 4.5 to 6.8 kg/ha and were also satisfactory. Average first alfalfa harvest yields (two experiments) following subsurface application of 1.6 kg/ha of inoculum with a sand carrier were 2,900, 2,750, 970, and 360 kg/ha for the 2, 4, 8‐week, and noninoculated treatments, respectively. With sufficient moisture availability, higher yields resulted from seed inoculation than from postemergence inoculation; however, those differences had largely disappeared by the third harvest. When applied as a surface spray under favorable environmental conditions, application of 1.4 kg/ha of peat‐base inoculum in 187 liters/ha of water produced first harvest alfalfa yields of 4,305, 3,985, 520, and 200 kg/ha for the 2, 4, 8‐week, and noninoculated treatments, respectively.
Forage Corn Response to Several Trickle Irrigation and Fertilization Regimes1
Authors: Yanuka M. , Leshem Y. , Dovrat A. 
Published: July 2010

AbstractThe main technical advantages of trickle irrigation are better water and nutrient control (frequent supply as needed by the plant) and less outside disturbance that may cause lower water and nutrient use efficiencies (wind, loss of pressure in irrigation pipes). The purpose of this investigation was to determine the yield level of forage corn (Zea mays L.), cv. Newe Ya'ar 170 at a density of 110,000 plants per hectare, and its nutrient and moisture uptake as affected by the application of different amounts of irrigation water when plant nutrients in the soil were sufficient for maximum growth.Crop water requirement (WR) was based on estimates of ET/Eo (ET = crop evapotranspiration and Eo = Class A pan evaporation) multiplied by Em (measured Class A pan evaporation). In order to derive the different irrigation treatments, WR was multiplied by a variable K, i.e., 1.5, 1.0, or 0.5, giving the total amounts of water applied by trickles of 693, 459, or 230 mm, respectively over an experimental period of approximately 100 days. The averages of daily water tension in several soil profiles, daily dry matter production rates, cumulative dry matter yield, and daily nutrient (N,P,K) uptake by the plant were measured.It was found that the ratio between dry matter yield and ET/Eo was approximately 290 kg ha−1day−1 for all treatments. This value is high in comparison with those reported in the literature. The response curve of dry matter yield vs. evapotranspiration began near the origin and was linear.The maximum dry matter yield, 32,440 kg/ha, was obtained with an average soil water tension of 4 centibars at 0 to 150 cm soil depth and average NO3‐N concentration of about 80 ppm in soil solution to a depth of 30 cm during the period of most active N uptake. Average P and K concentrations in the upper 30 cm of soil at that time were 20 and 80 ppm, respectively. The maximum rate of dry matter production was 660 kg ha−1day−1 at the time of grain filling.As expected, irrigation with trickles allowed efficient control of the fertilizer‐water‐soil system, maintaining high water and nutrient availability to the crop.
Tiller Development at the Coleoptilar Node in Winter Wheat1
Authors: Peterson Curt M. , Klepper Betty , Rickman R. W. 
Published: July 2010

AbstractThe formation of a secondary crown from a coleoptilar tiller can be important in wheat (Triticum aestivum L.) producing regions where severe frosts can destroy or limit primary crown development in winter wheat. The outgrowth of a tiller from the coleoptilar node is influenced by both seed and environmental factors. This study was conducted to determine and compare factors likely to affect the carbohydrate status of the seedling, including seed reserves, seedling leaves, irradiance, and planting density.Plants of ‘Stephens’ wheat, grown from seeds of three sizes, were maintained in a controlled environment. Before being sown, endosperm reserves were removed; after germination, the blade from one of the first three foliage leaves was excised to determine the influence of reduced endosperm and foliage leaf food sources on coleoptilar tiller development. Plants grown from largest seeds produced the most coleoptilar tillers, and these tillers appeared earlier in leaf development. The greatest number of subtillers and nodal roots were formed on coleoptilar tillers when plants from large seeds were grown under bright irradiance and a lower planting density. Treatments where a reduced number of coleoptilar tillers was obtained included: small seed sizes, blade excision from the first foliage leaf, intermediate irradiance, and high planting density. No coleoptilar tillers or nodal roots were produced at coleoptilar nodes both when endosperm reserves were excised prior to germination and when seedlings were grown under low irradiance. The length of the coleoptilar tiller and the number of its leaves at termination of the experiment were influenced both by seed size and irradiance levels during seedling development. The use of large seeds and adequate irradiance levels during early seedling growth resulted in more numerous coleoptilar tillers with more vigorous growth.
Moisture Deficits and Grain Sorghum Performance: Evapotranspiration‐Yield Relationships1
Authors: Garrity Dennis P. , Watts Darrell G. , Sullivan Charles Y. , Gilley James R. 
Published: July 2010

AbstractKnowledge of evapotranspiration‐yield (ET‐Y) relationships is fundamental in evaluating strategies for managing limited irrigation. The work reported here was done to develop ET‐Y functions for grain sorghum [Sorghum bicolor (L.) Moench], to provide base data for a water management improvement study in Nebraska. A field experiment was conducted using a modified line source sprinkler system to establish treatments that resulted in several different ET levels during each growth stage. The system was installed on a Valentine very fine sand (Typic Ustipsament) in west central Nebraska.The specific objectives of the study were: 1) to determine the crop evapotranspiration‐yield relationships for grain sorghum in this location, 2) determine how the timing and intensity of water deficits affect this relationship, 3) compare the evapotranspiration‐yield response of selected genotypes, and 4) to determine whether crop water use efficiency can be increased by judicious limited irrigation.In two seasons the relationship between evapotranspiration (ET) and grain yield (Y) or dry matter was linear. Evapotranspiration reduction under all conditions tested incurred some yield reduction. For a given genotype the slope of the ET‐Y relationship varied greatly depending on the growth period treatment. The lowest slopes were associated with a treatment in which stress built up steadily over the entire growing season. The slope was generally much steeper when irrigation was restricted to varying degrees for only a portion of the growing season. With greater yield reductions per unit of ET deficit, the latter treatments were considered suboptimal irrigation strategies compared to a gradual stress buildup.One hybrid had a lower slope of the ET‐Y relationship than the other genotypes for the treatment that provided water stress of gradually increasing severity. The percentage yield reductions were similar for all hybrids, however. The yield reduction ratios of the genotypes were different for the two growing seasons.Water use efficiency consistently decreased as ET declined below the maximum. It appeared that water stress, regardless of timing, tended to reduce water use efficiency. The reductions were smallest when stress increased gradually throughout the growing season.
Cultivation Effects on the Amounts and Concentration of Carbon, Nitrogen, and Phosphorus in Grassland Soils1
Authors: Tiessen H. , Stewart J. W. B. , Bettany J. R. 
Published: July 2010

AbstractCultivation has substantially reduced the organic matter contents of many prairie soils. This study attempts to quantify the losses of C, N, and P from three prairie soils of different textures during cultivation. For this purpose cultivated and adjacent uncultivated soils (2 Cryoborolls and 1 Cryorthent) were sampled and their C, N, and P contents as well as their bulk densities and horizon depths were compared.Reductions of about 35% in the C concentration were observed in clay and silt loam soils after 60 to 70 years of cultivation. At the same time reductions in N concentrations were greatly influenced by the presence or absence of legume [alfalfa, (Medicago sativa L.)] crops grown in the fields and losses varied between 18 and 34%. Phosphorus concentrations were reduced by 12% and all P losses were accounted for by the organic fraction. During a similar period of cultivation a lighter textured sandy loam had experienced greater reductions in C, N, and P concentrations of 46, 46, and 29%, respectively. In this soil P was lost from both the organic and inorganic fractions. Prolonged cultivation of 90 years did not result in a decrease in the rates of losses of C, N, and P on the silt loam soil.Conversion of concentration data to area based total C, N, and P budgets resulted in a decrease in the differences seen between cultivated and uncultivated soils. This was caused by an increase of soil bulk densities under cultivation and by an increase in the standard deviations of the data due to variability of horizon depths in cultivated fields.
Evaluating N Fertilizer Sources and Timing for Winter Wheat1
Authors: Christensen N. W. , Meints V. W. 
Published: July 2010

AbstractAmmonia volatilization can reduce the effectiveness of surface applied N fertilizers. Our objectives were to evaluate N source by timing interaction under field conditions conducive to NH3 volatilization and to compare the sensitivity of three approaches to assessing N source by timing interaction. Ammonium nitrate and urea fertilizers were topdressed at rates of 0, 34, 67, and 101 kg N/ha on 19 November or 23 March to ‘Winalta’ winter wheat (Triticum aestivum L.) grown on a nonirrigated Scobey silt loam (Aridic Argiboroll, fine, montmorillonitic). Plots receiving topdressed N contained sub‐plots fertilized at the appropriate rate and time with 15NH4 15NO3 or 15NH2CO15NH2 labeled fertilizers containing 1.31 atom percent 15N. Nitrogen fertilization increased straw yield, grain yield, grain protein, test weight, and N content of straw and grain. Uptake of soil N and fertilizer N in straw and grain were determined. Grain yield was fitted to a concurrent Mitscherlich regression model while total N uptake and fertilizer N uptake were fitted to multiple linear regression models to evaluate the relative effectiveness of each N source—timing combination. Comparison of regression coefficients for either grain yield or total N uptake revealed no significant differences between N source—timing combinations. Fertilizer N uptake regressed on rate of applied N was a better parameter for evaluating N source by timing interaction and showed that fall topdressed urea was only 69% as effective as fall topdressed ammonium nitrate. Spring topdressed urea, spring topdressed ammonium nitrate, and fall topdressed ammonium nitrate were equally effective in supplying N to wheat plants. Volatilization of NH3 from surface applied fertilizer probably accounts for the lower relative effectiveness of urea topdressed on 19 November.
Effect of Crop Residue Management and Tillage on Water Use Efficiency and Yield of Winter Wheat1
Authors: Cochran V. L. , Elliott L. F. , Papendick R. I. 
Published: July 2010

AbstractDirect drilling of winter wheat (Triticum aestivum L.) into surface cereal residues reduces soil erosion but frequently has resulted in stunted plants and lower grain yields than conventional planting methods. Phytotoxins produced during decomposition of surface crop residues have been implicated as the cause of these reduced yields. Field plots were established on spring and winter wheat stubble to compare plant stands, water storage, grain yields, and water‐use efficiency between direct drill seeded and conventionally seeded winter wheat. Residue management treatments included: standing stubble, complete residue removal, moving the crop residue from the seed row, and residue incorporation. New sites were used each year with the spring and winter wheat stubble maintained on Naff silt loam (fine‐silty, mixed, mesic Ultic Argixerolls) and Palouse silt loam (finesilty, mixed, mesic pachic Ultic Haploxerolls), respectively. Water soluble phytotoxins from the surface crop residues were not found during the 3‐year study. Furthermore, moving the crop residues from the seed row did not affect yields, but did alleviate the high crown node set which in turn reduced visual injury from soil active herbicides. Surface crop residues significantly improved water storage during the one season with a major runoff event, which increased grain yields and water use efficiencies, but had no effect when soil profiles were filled by spring. During the 3‐year study, winter wheat yields from plots direct drilled into surface cereal residues were equal to those from plots tilled and seeded conventionally.