bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nodulating and Non‐nodulating Lee Soybean Isolines Response to Applied Nitrogen1
Authors: Bhangoo M. S. , Albritton D. J. 
Published: July 2010

AbstractFurther studies on N fertilization of soybeans [Glycine max (L.) Merr.] were needed for better understanding of the relative capacity of soybeans to fix atmospheric N and utilization of applied or soil N and fixed N. Field experiments with nod and non‐nod Lee isolines were conducted for 3 years on a prelimed Calloway silt loam (fine‐silty, mixed, and Thermic family of Glossaquic fragiudalfs). Nitrogen in the form of NH4NO3 at the rates of 0, 56, 112, 224, and 448 kg/ha was applied each year. Grain and vegetative matter yield, N content and total N uptake showed significant increases from applied N each year. Grain yields of nod Lee from the no‐N treatments equalled those of the non‐nod Lee at the 0 and 56 kg N/ha in 1973 and at the 112 and 224 kg N/ha rates in 1971 and 1972, respectively. Yields of both isolines were highest and similar at the 224 and/or 448 kg N/ha rates each year. Higher grain yield and total N uptake in the non‐nod no N, 56, and 112 kg N/ha rates especially in 1973 indicated utilization of soil and applied N. Utilization of applied and soil N along with fixed N was evident in both isolines each year. Of the total N uptake, the amount of fixed N in the no‐N treatments in 1971 and 1972 was 51.0 and 63.9%, respectively, and was 22.1% in 1973, possibly because of high residual soil N. Symbiotic N fixation decreased practically to zero when N rates exceeded 224 kg/ha. The 56 kg N/ha had little effect on N fixation. Applied or soil N along with fixed N appeared to be essential for maximum soybean yields on poorly drained soils low in organic matter with a strongly acid subsoil. Rates of N applied should be within the range where symbiotic fixation is not inhibited and should be based on the residual soil N.
Evaluation of Protein and Nutritive Fiber Content of Cultivated Russian‐Thistle1
Authors: Farmer David A. , Fowler James L. , Hageman James H. 
Published: July 2010

AbstractRussian‐thistle (Salsola sp.), a troublesome weed in the arid and semiarid regions of the United States, has been successfully harvested and used as a forage when cultivated forages were limited or unavailable. Over the years, the few published reports of studies of water use efficiency and nutritive value of Russian‐thistle have been sufficiently encouraging to suggest its potential as a forage crop in areas where water resources are limited. Therefore, this study was undertaken to determine the effect of nitrogen fertilization on some of the nutritional qualities of Russian‐thistle.Russian‐thistle plants were grown in a greenhouse in 15‐liter pots; urea levels corresponding to 0, 28, 56, 84, and 112 kg of N/ha were applied, and all plants were watered uniformly. Under these conditions, no correlations were found between nitrogen application and total crude protein, acid detergent fiber, or acid detergent lignin; nevertheless, average values of 19.8, 34.4, and 6.4 (percent dry weight) were measured for each of these, respectively. In addition, the amino acid composition of the total protein was well balanced nutritionally. Only at the highest nitrogen applications was nitrate observed to approach potentially dangerous levels. Values obtained are comparable to many commonly used forages. Studies to determine the effect of nitrogen and water application on the nutritional qualities of Russian‐thistle under field conditions are underway.
Response of Festuca rubra L. Seedlings to Ethephon1
Authors: Nittler L. W. , Kenny T. J. 
Published: July 2010

AbstractSeed characteristics are not distinctive enough for reliable identification of Festuca rubra L. cultivars; therefore, research was conducted to identify seedling characteristics useful for cultivar purity testing. Starting 2 weeks after seeds were planted, seedlings were sprayed three times, at 3‐day intervals, with 700 μl/liter of ethephon (2‐chloroethyl‐phosphonic acid) until the foliage was completely wet. This resulted in development of two distinctly different types of plants. The first had long‐narrow‐leaf blades and the second had short‐wide leaf blades. All seedlings of the Chewing fescue cultivars ‘Cascade’, ‘Highlight’, and ‘Jamestown’ were of the long‐narrow leaf type. In contrast, all seedlings of ‘Rainier’ and 98% of the seedlnigs of ‘Ruby’ red fescue were of the short‐wide leaf type. ‘Arctared’, ‘Illahee’, and ‘Pennlawn’ red fescue developed 74, 36, and 39% short‐wide leaf plants respectively. Even though this technique distinguishes only two types of plants, it was useful in determining accuracy of labeling of Festuca rubra L. seed samples.
Nitrogen Content of Winter Wheat During Growth and Maturation1
Authors: Daigger L. A. , Sander D. H. , Peterson G. A. 
Published: July 2010

AbstractPreliminary studies showed that winter wheat (Triticum aestivum L.) was losing relatively large amounts of N during the grain formation growth period. In order to further document this N loss, winter wheat plants were sampled at different times and at different locations before and after anthesis until maturity. The objective was to determine the nature and extent of dry matter and N losses that occur during the later stages of wheat development as influenced by N fertilization. While N is translocated rapidly from other plant parts to the grain after anthesis, total N losses ranged from 25 to 80 kg ha−1 in different experiments. These losses occurred during the grain filling period after anthesis. Dry matter and N losses were attributed primarily to the stems where 83 to 87% of dry matter losses occurred and 73 to 75% of the N. Dry matter and N losses from leaves and roots were relatively small. The N losses increased with increasing rates of N application. Plant N losses could account for much of the N losses found in soil N balance studies and certainly influence calculations involving fertilizer N efficiency. Grain protein could be doubled if plant N losses could be translocated instead into the grain.
Seed Grade Effect on Corn Performance1
Authors: Hicks D. R. , Peterson R. H. , Lueschen W. E. , Ford J. H. 
Published: July 2010

AbstractSmall‐sized or ungraded corn (Zea mays.) seed usually costs less than large‐graded seed. Since planters can now uniformly plant ungraded and/or small seed, we conducted trials at Waseca and Lamberton, Minn., in 1973 and 1974 to determine the effect of seed size and shape on performance of early compared to late‐planted corn.Four seed grades — large round (LR), large flat (LF), small round (SR), small flat (SF), and mixed (M) — were evaluated each year. The M category was an equal mixture of the four grades. In 1973, the single cross hybrid ‘A639 × A638’ was used; in 1974 we used ‘DeKalb XL45A’ and ‘DeKalb XL43.’ Early plant height, early plant dry weight, and tassel dates were recorded at the Waseca location and grain yield was measured at both locations.Seed grades did not affect corn yields when data were averaged over years, locations, and hybrids. In only one of 12 comparisons was there a seed grade effect with higher yields from graded vs. ungraded seed, from large vs. small seed, and from round vs. flat seed. Seed grade did not affect early plant height or tassel dates. Early plant dry weight for plots seeded with SR and SF seeds was lower than that of plots seeded with LR or LF seeds in 1973; only very small plant dry weight differences occurred in 1974.Grain yields from the early May planting were higher than from late May planting for all location‐years except Waseca in 1973. Interactions of seed grade with planting dates or hybrids were not statistically significant for three of the four location‐years of the study. Soil temperature at the 10‐cm depth for the 2 weeks post planting was 8 to 10 C colder for early vs. late planting dates, yet yields from SR and SF seed were equal to those from LR or LF.
Effect on Tuber Yield of the Exposure of Yam Tubers to Light1
Authors: Gumbs F. A. , Ferguson T. U. 
Published: July 2010

AbstractThis study was designed to determine the effect of exposure of yam (Dioscorea alata L.) tubers to light on tuber yield, since the emergence of yam tubers from the ground as a result of a compacted or restricting soil layer was found by the authors in previous unpublished studies to be associated with reduced tuber yield. Yam tubers were allowed to develop in the absence of soil, and in a separate compartment from the roots, in specially designed wooden growth boxes. Tubers were allowed to develop in total darkness, in continuous day. light or, with exposure to light for 30 min once per week. Continuous exposure of the developing tubers to daylight significantly reduced tuber yield and caused a large number of small tubers to be produced. Periodic exposure of the tubers to light did not significantly reduce tuber yield nor tuber number compared to tubers developing in total darkness. Exposure of the tuber to light did not significantly affect leaf number but there was some effect on leaf area.
Performance of the Silver‐foil Psychrometer for Measuring Leaf Water Potential in situ1
Authors: Hoffman Glenn J. , Hall Anthony E. 
Published: July 2010

AbstractContinuous in situ measurements of leaf water potential are often needed in studies of the soil‐plant‐atmosphere continuum. The development of the silver‐foil thermocouple psychrometer has made these measurements possible. The objective of this investigation was to evaluate the performance of the silver‐foil psychrometer under various steady‐state and dynamic conditions. Leaf water potential measurements were made in situ on pinto bean (Phaseolus vulgaris L.) in a controlled‐environment plant chamber where temperature, relative humidity, CO2 concentration, radiation, and photoperiod were precisely controlled.Typically, the psychrometer will reach equilibrium with an intact leaf 2 hours after attachment. Consistent leaf water potentials are attainable when the leaf temperature varies by as much as 0.25 C/min. This thermal stability is as good as that of any multijunction psychrometer described to date. At radiation levels below 50 Wm−2, leaf water potential readings can be made on unshaded leaves; above this level, the leaf must be shaded to prevent thermal gradients across the leaf and psychrometer.The silver‐foil psychrometer responded to rapid osciliations in leaf water potential. During oscillations, leaf water potential preceded leaf conductance and transpiration by one‐third of the oscillation period. Net photosynthesis oscillated in phase with leaf conductance, indicating that net photosynthesis is limited by the internal CO2 concentration, even at very low irradiances.
Growth and CO2 Assimilation by Corn as Related to Potassium Nutrition and Simulated Canopy Shading1
Authors: Smid A. E. , Peaslee D. E. 
Published: July 2010

AbstractRadiant flux density and K are potentially limiting factors in CO2 assimilation by corn leaves having the common property of being more accessible to the upper leaves than to lower leaves of the plant canopy. In this experiment, the effects of K nutrition and shading on growth and CO2 assimilation were evaluated in the absence of confounding factors such as differentials in moisture supply, rooting volume, and availability of other nutrients that often accompany studies having variable plant populations. Corn was grown outdoors in sand cultures receiving solutions containing 15, 45, 135, or 400 μg of K/ml. Plant populations of 33,000, 98,800, and 118,000 plants/ha were simulated by progressive artificial shading of each plant with layers of shade cloth during growth. Rates of CO2 assimilation by selected leaves, yield of dry matter, and leaf concentrations of K were measured at the silking stage. In general, CO2 assimilation rates increased with K levels, with simulated population, and with proximity to the plant top. However, these relationships were complex as evidenced by a significant interaction of K ✕ leaf location and K ✕ population ✕ leaf location. The interactions apparently were associated with increases in leaf K concentrations due to less growth with shading and to movement of K from lower into upper leaves under conditions of K stress. Across all treatment combinations, CO2 assimilation was highly correlated (r = 0.89) with tissue levels of K. Thus, the effects of shading and leaf position were indirect through their influence on the concentrations of K in leaf tissue. Measured assimlation rates (mg/hour) at canopy illumination levels for leaves 5, 7, and 9, when the entire leaf surface was considered uniformly photosynthetic provided indices that were highly correlated (r=0.96, significant at the 0.01 level) with yields of dry matter per plant.
Simulation Model for Nutrient Uptake from Soil by a Growing Plant Root System1
Authors: Caassen N. , Barber S. A. 
Published: July 2010

AbstractMathematical models of nutrient uptake by plants are useful for investigating the effect of various soil and plant factors on nutrient flux to plant roots. The objective of this research was to develop a model based on theoretical considerations of the processes of nutrient uptake by plant roots growing in soil and then to test the model experimentally. The soil and plant factors used in the model were to be measured independent of final nutrient uptake.The model for flux by mass flow and diffusion to the root was patterned after that of Nye and Marriott. The absorption kinetics of the root were assumed to follow Michaelis‐Menten kinetics. The Nye‐Marriott model gives the nutrient concentration at the root with time. From this accumulated uptake per cm2 of root surface with time was calculated. Rate of root growth was assumed exponential for the growth of the young plant. Uptake per cm2 of root with time was combined mathematically with rate of root growth to get total uptake with time by the plant. The present program assumes root hairs do not affect uptake and that roots do not compete for nutrients.A computer program was written for solution of the mathematical model. The factors required in the model from the soil are: effective average diffusion coefficient, initial nutrient concentration in solution, and buffering capacity. For the plant they are: the relation between nutrient concentration in solution and net influx into the root, water influx, root radius, initial root length, and rate of root growth.The model was tested for measuring K uptake by corn (Zea mays L.) from eight different soil‐K combinations. The corn was grown in a growth chamber and K uptake was measured for the period of plant growth from 4 to 10 and 13 days. The calculated uptake, y, was correlated with observed uptake, x, by the equation y = 0.155 + 1.566 × (R2 = 0.87) where y and are μmoles of K/plant. Calculated uptake was overestimated by about 50%, possibly because competition occurred between roots for soil K and K was not absorbed by the root as fast at night as in the day.The model should be useful for investigating the principles of nutrient absorption by plant roots from soil which can be used for developing more efficient systems of fertilizer application.
Yield and Nitrogen Utilization by Rice as Affected by Method and Time of Application of Labelled Nitrogen1
Authors: Reddy K. R. , Patrick W. H. 
Published: July 2010

AbstractRecent increases in the cost of N fertilizer make it important to examine methods of improving the utilization of fertilizer N by lowland rice (Oryza sativa L.). The objective of the present investigations was to compare the effects of different methods and times of N application on yield and utilization of N by lowland rice. Field experiments using labelled fertilizer N were carried out during 1974 and 1975 utilizing different times and methods of application of ammonium sulfate on small field plots (2.32 m2). Fertilizer N was applied either by deep placement at the beginning of the season or at one or more times during the growing season as surface application. Relative contributions of native soil N and fertilizer N sources to plant uptake were followed during the growing season, and total uptake of native soil N and fertilizer N by rice was determined at harvest.Highest grain yields were obtained where all of the N was applied early in the growing season or where part of the N was applied in early season and part applied no later than mid season. Late season application of part of the nitrogen was not as effective. In 1974, recovery of fertilizer N (in grain and straw) was highest in the plots receiving all N by deep placement, while in 1975 split application (half at early season and half at mid season) gave greatest N utilization. For the 2 years, the recovery of fertilizer in grain and straw ranged from 33 to 61% of applied N. Rice plants derived more fertilizer N during the early part of the growing season with the rate of uptake decreasing as the season progressed. Recovery of fertilizer N calculated from labelled N data showed lower values, compared to the recovery of fertilizer N estimated by a method based on total N uptake difference between the plots receiving N and the untreated plots. More native soil N was taken up by the crop from the plots receiving fertilizer N than from the check plots in 1974, but there was little difference in uptake in 1975.
Photosynthesis, Transpiration, and Leaf Elongation in Corn Seedlings at Suboptimal Soil Temperatures1
Authors: Barlow E. W. R. , Boersma L. , Young J. L. 
Published: July 2010

AbstractThe physiology of plant response to low soil temperatures is not well understood. Laboratory studies were conducted to examine the relative sensitivities of rates of leaf elongation, net photosynthesis, and transpiration and the leaf water potential of corn seedlings (Zea mays L. ‘Pride 5’) to decreasing temperature. These parameters were simultaneously monitored, as the soil temperature was decreased from 28 to 10 C at about 4 C increments. The different soil temperatures were imposed during a 10‐hour period on 14‐day‐old plants with seven exposed leaves growing at a 27.5 C air temperature, a 55% relative humidity, and a light intensity of 753 μE/m2/sec.Any decrease of the soil temperature below 28 C decreased the leaf elongation rate. This was attributed to restricted water uptake which lowered the plant water potential and to the temperature decrease of the shoot apical meristem region. Leaf elongation ceased at the plant water potential of —9 bars due to decline of leaf turgor pressure.Neither transpiration nor net photosynthesis was reduced significantly until the plant water potential reached —12 to —13 bars. Increases in both stomatal and internal resistances to CO2 diffusion coincided with the decreased net photosynthesis at low plant water potentials. Suboptimal soil temperatures affect corn seedling growth primarily by decreasing leaf elongation.
Influence of Three Soil‐water Regimes on Root Porosity and Growth of Four Rice Varieties1
Authors: Das D. K. , Jat R. L. 
Published: July 2010

AbstractA better understanding of the growth response of rice (Oryza sativa L.) to waterlogged soil conditions is desirable. The objective of this study was to measure the influence of soil water regime on root porosity, growth, and nutrient content of four varieties of rice at various dates after transplanting.Four rice varieties (‘IR8’, ‘Padma’, ‘BC6’, and ‘IR22’) were grown under three soil water regimes (continuous flooding, alternate flooding, and no flooding) in a greenhouse on a clay loam soil. Root porosity, growth of plants and nutrient (N, P, K, Ca, and Mg) content of shoots were determined at four different plant ages (30, 60, 85, and 110 days after transplanting).Root porosity was greatest in plants grown with continuous flooding. Porosity of roots in all four varieties reached maximum values between 30 and 60 days and then started to decline. Padma and BC6 had higher root porosities than IR8 and IR22. High root porosity was associated with greater root length, increased dry weight of roots and shoots, and higher nutrient content in shoots.
Influence of Simulated Early Lodging upon Soybean Seed Yield and its Components1
Authors: Woods S. J. , Swearingin M. L. 
Published: July 2010

AbstractEarly lodging of soybeans [Glycine max (L.) Merr.] in highly productive environments has been observed throughout the midwestern United States. It has been established that soybean seed yields are decreased when severe lodging occurs sometime prior to physiological maturity. The objective of this 2‐year field study was to examine the effect of plant growth stage at the time of lodging on soybean seed yield and its primary components; pods per plant, seeds per pod, and seed size.The study was conducted at Tipton, Ind., in 1972 on a Crosby silt loam soil (member of the fine mixed mesic family of Aeric Ochraqualfs) and at Lafayette, Ind., in 1973 on a Chalmers silty clay loam soil (member of the fine loamy mixed mesic family of Typic Haplaquolls.) Two Group II soybean cultivars (‘Wells’ and ‘Corsoy’), representing distinct degrees of lodging resistance, were subjected to a simulated lodging treatment at 2‐week intervals in the early reproductive growth stages. Controls were: a) plants supported by a 10 ✕ 10 cm plastic grid system, and b) no treatment or support which permited natural lodging to occur. Depending upon the time of simulated lodging, seed yields of both cultivars were reduced from 11 to 32% in 1972 and from 12 to 22% in 1973. The reproductive growth stage, R5, normally reached during the first 2 weeks of August in central Indiana, was found to be the most critical time for lodging to occur. Neither seeds per pod nor seed size was significantly reduced when lodging occurred at stage R5. The reduction in yield was due almost entirely to a reduced number of pods per plant, especially those on the central stem. When lodging occurred after flowering had commenced apical dominance was lost, resulting in lateral branches assuming central stem characteristics.
The Brown‐Rosenberg Resistance Model of Crop Evapotranspiration Modified Tests in an Irrigated Sorghum Field1
Authors: Verma Shashi B. , Rosenberg Norman J. 
Published: July 2010

AbstractThe Brown‐Rosenberg (1973) resistance model was modified to simplify its calculation and increase its usefulness for estimating evapotranspiration. The model requires inputs of net radiation, air temperature, and vapor pressure and canopy and boundary layer resistance. The first three of these parameters are measured. In the modified version canopy resistance is estimated from a functional dependence on irradiance. The boundary layer resistance is estimated from a functional dependence on windspeed. The modification was tested in an irrigated sorghum (Sorghum bicolor Moench, cv ‘Rs 633’) field at Mead, Neb.The model predictions generally agreed to within 10%, on both an hourly and daily basis, with direct lysimetric and Bowen ratio‐energy balance measurements of evapotranspiration from the sorghum.The Brown‐Rosenberg model in its original and modified forms is useful when neither direct nor remotely sensed crop canopy temperature data are available and when there is need to evaluate the impact on evapotranspiration of several of the aforementioned environmental and crop parameters.