bluuebunny/crossref_metadata_2025 huggingface dataset:
Forage Production of Triticale Relative to Other Spring Grains1
Authors: Ciha A. J.
Published: July 2010

Small grains have been used in various regions of the United States and Canada as a source of forage; however, forage yield and quality from spring seedings have not been evaluated adequately. A field study was conducted on a Palouse silt loam (fine‐silty, mixed, mesic pachic Ultic Haploxerolls) to compare the forage production of two spring seeded triticale (Triticale hexaploide Lart.) lines (VT75229 and CF76) to currently grown oats (Avena sativa L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.) cultivars in eastern Washington. Forage yield, percent crude protein, and crude protein yield were determined at the heading and the soft‐dough stage of development from an early and a normal date of planting for the area. Forage yields were not significantly affected by planting date or any of the interactions containing planting date; however, there was a significant increase in percent crude protein with all species except barley when seeded at the normal compared to an early planting date. Triticale CF76 had a mean forage yield averaged over years and planting dates generally equal to the other spring grain species at the soft‐dough stage, but lower than barley and oats at the beading stage. Crude protein yield for the triticales was similar to the other spring grains under the majority of planting dates and harvest stages. These data indicate that triticale will have forage yields and crude protein yields equal to other spring grains in the Pacific Northwest; however, management factors, i.e., planting date and stage of harvest, need to be considered in making recommendations to producers in order to obtain maximum forage potential.
Temperature and the Development of the Taproot and Lateral Roots of Four Indeterminate Soybean Cultivars1
Authors: Stone J. A. , Taylor H. M.
Published: July 2010

Soil temperatures vary with depth and time within and among years. An experiment was conducted to quantitatively evaluate the effects of temperature on the development of the taproot and lateral roots of four soybean (Glycine max (L.) Merr.) cultivars at four temperatures. ‘Beeson’, ‘Hawkeye 63’, ‘Wayne’, and ‘Harosoy 63’ soybeans were grown at 17, 21, 25, and 29°C, using a specially designed, constant‐temperature, water bath system. The water bath was located in a temperature‐modified greenhouse where air temperature ranged from 20 to 35°C during the 12‐month experimental program. Serial measurements of taproot and lateral root tip location and number of primary nodes were recorded on alternate days until 19 days after emergence. A primary node was defined as the position at which one or more 1st order laterals emerge from the taproot. The rate of taproot extension increased with temperature, decreased with time at temperatures greater than 17°C, and was greater for the Beeson and Hawkeye 63 cultivars than for the Wayne and Harosoy 63 cultivars when averaged over time. The rate of lateral root extension increased with temperature, increased with time at temperatures less than 29°C, and was greater for the Beeson and Hawkeye 63 cultivars than for the Wayne and Harosoy 63 cultivars at temperature treatments greater than 17°C when averaged over time. The number of primary nodes varied with depth, time, and cultivar. The greatest number of nodes occurred 2.5 to 7.5 cm below the vermiculite surface. The Beeson and Hawkeye 63 cultivars had fewer primary nodes than the Wayne and Harosoy 63 cultivars. The results indicate that the depth of soybean root penetration can be altered to increase available water during periods of stress by cultivar selection and changes in soil temperature.
N2‐Fixation in Field Beans Quantified by 15N Isotope Dilution. I. Effect of Strains of Rhizobium phaseoli1
Authors: Rennie R. J. , Kemp G. A.
Published: July 2010

Most soils sown to field beans (Phaseolus vulgaris L.) contain indigenous Rhizobium phaseoli; thus, few studies have evaluated the effect of different strains of R. phaseoli on N2 fixation and yield of bean cultivars. Since western Canadian soils contain no indigenous R phaseoli, strains were screened for their ability to fix N2 in two bean cultivars, Aurora and Kentwood. Initially, the N2‐fixing ability of 19 strains of R phaseoli was determined in vitro. The best were then compared with 16 superior Centro Internacional de Agricultura Tropical strains in a 2‐ year International Bean Inoculation Trial in the field in association with the same two small white bean cultivars. 15N isotope dilution at levels of 15N natural abundance in the field showed the % Ndfa (percentage plant N derived from the atmosphere) averaged 50% for Aurora but only 32% for Kentwood over all 16 strains. The % Ndfa did not vary between the two experimental years, but due to different levels of soil N, yield and actual amounts of N2 fixed did vary. Aurora averaged 70 kg N ha−1 and Kentwood 37 kg N ha−1 fixed. Some strains fixed more than 100 kg N ha−1 in Aurora, resulting in dry matter and N yields in excess of uninoculated treatments receiving 40 or 100 kg fertilizer N ha−1. Strains of R phaseoli from high temperature soils of Latin America fixed high amounts of N2 in association with temperate bean cultivars under conditions of low temperature growth (10 to 23°C). CIAT strains 632,899, 640, and 904 and commercial Nitragin were highly efficient N2 fixers with Aurora as were CIAT strains 952, 161, 166, and commercial Nitragin with Kentwood. Thus, R. phuseoli are as efficient as other rhizobia in supplying fixed N2 to their host plant and, in N2‐fixing mode, certain bean cultivars can meet their genetic yield potential in the field without the addition of fertilizer N.
Dry Matter Production in Tops and Roots of Winter Wheat as Affected by Phosphorus Availability During Various Growth Stages1
Authors: Sutton P. J. , Peterseon G. A. , Sander D. H.
Published: July 2010

The timeliness of P availability to a plant is important for maximum plant growth. There is little information pinpointing the critical time(s) in the life cycle of winter wheat (Triticum aestivum L.) at which P uptake is the most important for maximum growth response. The objectives of this research were: i) to determine the effects of removing P from the growing medium during progressive stages of growth on dry matter production and P uptake of winter wheat; and ii) to compare the P demand pattern of winter wheat with that known for spring wheat. ‘Centurk’ winter wheat was grown using a modified Hoagland's nutrient solution in a greenhouse environment. Treatments consisted of evaluating the plant response to the time grown with and without available P in the nutrient solution. This was accomplished by replacing the complete nutrient solution with a nutrient solution devoid of P and allowing plants to continue growth to physiological maturity. Winter wheat had taken up sufficient P by the first node stage to ensure maximum dry matter production of the mature roots and tops. Phosphorus availability in later growth stages did not significantly increase mature root and top dry matter production. Maximum grain yield at maturity, however, was only realized when P was available through the mealy‐ripe stage (Feekes' Scale 11.2) of grain development. It appears that after noding stage only a small amount of P may be needed to allow carbohydrate translocation mechanisms to function. Spring wheat differs from winter wheat in that it only requires adequate P up to heading to produce maximum grain yields.
Extractors for Neutron‐Probe Access Tubes1
Authors: Wesley Richard A. , Adams E. Ray
Published: July 2010

Extraction of neutron probe access tubes from soils can often be time consuming and costly if not properly managed. Therefore, two neutronprobe access tube extractor units were designed, constructed, and tested for ease of use and damage‐free results. One unit was made from a tail pipe expander and was capable of extracting tubes from soils with low moisture content but resulted in time delays because of slippage on the tube and also resulted in some damaged and distorted tubes. The other unit was made from an expanding mandrel and performed acceptably on both coarse and fine‐textured soils having both high and low moisture content. This unit eliminated time delays because of slippage and virtually eliminated damaged and distorted tubes.
Interactions among a Herbicide Program, Nitrogen Fertilization, Tarnished Plant Bugs, and Planting Dates for Yield and Maturity of Cotton
Authors: Gaylor Michael J. , Buchanan G. A. , Gilliland F. R. , Davis R. L.
Published: July 2010

The influence of a maximum herbicide program, N rates, tarnished plant bugs [Lygus lineolaris (Palisot de Beauvois)], planting date, and interactions among these treatments on cotton (Gossypium hirsutum L.) was determined under field conditions on a Dewey silt loam (clayey, kaolinitic, thermic, Typic Paleudult) soil. High rates of herbicides caused early phytotoxicity and reduced earliness in all 3 years of this study. Total yields were reduced by herbicides in 1976 and 1978. In 1977, compensation for early season herbicide injury by the early‐planted cotton apparently resulted in higher yields in the herbicide treated plots than in untreated plots. Generally, the herbicide program reduced earliness and yields most under conditions where the potential yield was greatest (early planting, high N rates, and effective tarnished plant bug control). Yield reductions due to the herbicide program were not additive with reductions due to other factors. Effects of variable N rates on yield were inconsistent. Tarnished plant bugs reduced total yields in cotton planted late in 1976, but because early‐planted cotton had time to compensate for damage, plant bug infestations resulted in no yield loss in the early 1976 planting and in increased total yields in cotton planted early in 1977. Because of complex interactions among production practices, interdisciplinary research is needed to design optimum production systems.
Pangola Digitgrass Yield and Nutrient Uptake with Liquid and Solid N‐P‐K Fertilizers1
Authors: Mooso Galen D. , Jolley Von D.
Published: July 2010

‘Pangola’ digitgrass (Digitaria decumbens Stent.) is an important tropical and subtropical forage species which responds dramatically to N fertilization. Responses to the application of P and K, however, or the combinations of N, P, and K are not as clearly defined. Its response to N, P, and K applied in solution has not been established. A 2‐year study to compare the effect of the application of liquid and solid N‐P‐K (9:1:4) fertilizers on digitgrass production and nutrient uptake was conducted on a Wabasso sand (siliceous, hyperthermic, Alfic Haplaquod) on the Deseret Ranches in Central Florida. There was a positive linear relationship between the amount of N‐P‐K fertilizer applied and the amount of forage produced. The concentrations of N and K were positively affected by increased N‐P‐K levels while P concentration was negatively affected. A positive linear relationship was also observed between the uptake of N, P, and K and the rate of application. The liquid fertilizer produced an average of 20.9 and 21.4% less forage than the solid for 1980 and 1981, respectively. Solid fertilizer maintained a higher N concentration in the forage than the liquid, but no differences in P and K concentrations were observed with the two forms of fertilizer. The forage treated with solid fertilizer averaged 24, 35, and 59% higher relative uptake of N, P, and K than the forage treated with liquid fertilizer, respectively. Under the conditions of the study, ammonia volatilization was probably the major reason for lower yields, N concentrations, and N uptake from the use of liquid fertilizer. The lower uptake of P and K with liquid fertilizer was associated with the lower yields obtained with this source.
Yield of Corn, Cowpea, and Soybean Under Different Intercropping Systems1
Authors: Allen James R. , Obura Robert K.
Published: July 2010

Intercropping is presently a major method of crop production in tropical Africa, subtropical Asia, and Central and South America. With this approach, crops are planted in such a variety of combinations that the merits of intercropping as compared with monoculture are often difficult to determine. Our objective was to evaluate the merits of intercropping legumes and grasses in the United States. Corn (Zea mays L.) was intercropped with cowpea (Vigna unguiculata (L.) Walp.] and soybean [Glycine max (L.) Merr.] on a Norfolk sandy loam soil (fine, loamy siliceous, thermic Typic Paleudult). The legumes were either planted in the rows with corn or alternate to the corn rows. Control plots were monocrops of corn and the legumes, with each species fertilized according to soil test recommendations. Both dry matter and seed yield of the monocrops were higher than the individual components in the intercrops. Intercropped corn yield ranged from 46 to 90% of the reference monoculture. The lower dry matter production in the intercropped plots may have been due to competition between the corn and legume components for N. Seed yield of intercropped cowpea ranged from 42 to 56% of monoculture. Intercropped soybean seed yield ranged from 52 to 54% in 1980, and 48 to 60% in 1981 of the monoculture. Dry matter accumulation was significantly greater for the monocrops but varied non‐significantly, between the alternate and within row system. The corn‐cowpea intercrops, which had Land Equivalent Ratios (LER) up to 1.27 in 1980 and 1.32 in 1981 and Area Time Equivalent Ratios (ATER) as high as 1.19 in 1980 and 1.25 in 1981, were more productive than the corn‐soybean intercrops. The corn‐soybean combination had a maximum LER in 1980 of 1.22 and 1.10 in 1981, while the maximum ATER was 1.12 in 1980 and 1.01 in 1981. Thus, both the LER and ATER showed that intercropping resulted in greater productivity per unit of land than monocultures of the intercrop components.
Sprouting in Intact Mature Spikes of Hard Red Spring Wheat1
Authors: Bauer Armand , Black A. L.
Published: July 2010

The water factor's role in sprouting was defined for intact mature hard red spring wheat (Triticum aestivum L.) spikes in laboratory experiments as a prelude to developing a sprouting model. Grain and spike water concentration are essentially synonymous at harvest ripeness. Spike water concentration increased linearily by 10 g kg−1 min−1, dry wt at 69°C, when continuously misted at 19 mm h−1, while water imbibition by grain in once wetted intact spikes increased curvilinearily, varying with spike water concentration and equilibration time. Maximum imbibition rate of grain was 17 g kg−1 h−1 with wheat spike water concentration at 1450 g kg−1. Water evaporation from wetted spikes was slower at high than low relative humidity, and slower after equilibration (time for imbibition) than if drying was initiated immediately after wetting. Minimum equilibrated spike water concentration inducing sprouting was about 450 to 490 g kg−1. Sprouting was not induced by wetting field‐growing wheat during primary dehydration until the water concentration had declined to about 120 g kg−1 for at least 2 days. When cut at Feekes stage 11.3, the number of drying days required before any sprouting could be induced varied with cultivars, ranging from about 4 to more than 15 days. Sprouting potential was enhanced by wetting‐drying cycles in which the wetted interval was too brief to permit sufficient imbibition to initiate sprouting. Ninety percent of the kernels in 300 mature spikes sprouted within 8 days after misting to saturation (about 1500 g kg−1 water concentration) and maintained at a minimum of 750 g kg−1; 20% of the kernels sprouted within 28 h of initiation of wetting.
Predicting Soybean Rooting Depth as a function of Soil Temperature1
Authors: Stone J. A. , Kaspar T. C. , Taylor H. M.
Published: July 2010

A two dimensional predictive simulation of rooting depth has been developed from data which describe the effects of root‐zone temperature on soybean [Glycine max (L.) Merr.] root development. The major inputs are equations which describe the rate of taproot and lateral root extension, node development, and the rooting angle as a function of time and temperature. The simulation predicts the extension of the taproot and 10 primary lateral roots for two groups of soybean cultivars. The output consists of a listing of serial rectangular coordinates for each root tip and a computer plot of the root system. The rooting depths predicted by the simulation agree well with field experimental data illustrating the importance of soil temperature in determining the depth of soybean root penetration in extrapolating greenhouse root extension data to a field situation.
Fruiting of Cotton. I. Effects of Moisture Status on Flowering1
Authors: Guinn G. , Mauney J. R.
Published: July 2010

abstract

Yield of cotton (Gossypium hirsutum L.) is proportional to the number of bolls produced, which is influenced by flowering rate and boll retention. Previous reports have presented conflicting information on the effects of water deficit on fruiting some indicated increased flowering while others indicated decreased flowering in response to water deficit. Tests were conducted in 1978, 1979, and 1980 on an Avondale clay loam (a member of the fine‐loamy, mixed, hyperthermic family of Typic Torrifluvents) at the Arizona Cotton Research Station in Phoenix to determine the effects of plant water status at different times during the season on flowering of cotton. Water deficits decreased flowering in 1978 and 1980. A pronounced lag in response caused flowering to continue unabated during much of each stress period. Once the flowering rate declined, however, it did not start to recover until about 3 weeks after stress was relieved by irrigation. Only in 1979 did we observe more flowers in plots in which the first postemergence irrigation was delayed. The population of lygus bugs (Lygus hesperusKnight) was higher in 1979 than in 1978 or 1980. Furthermore, lygus counts were higher in irrigated than in stressed plots. Because lygus bugs have been shown to cause square shedding, early irrigation may have decreased early flowering indirectly in 1979 by increasing bug populations and resultant square shedding. We found no evidence, however, for a physiological stimulation of flowering of cotton by a water deficit.
Soybean Seed Growth II. Individual Seed Mass and Component Compensation1
Authors: Spaeth S. C. , Sinclair T. R.
Published: July 2010

abstract

Since the rate and duration of the growth of individual seeds determine final seed mass, a detailed study of these variables with respect to morphological position on individual soybean [Glycine mar (L.) Merr.] plants was undertaken. A predictable pattern of seed growth could lead to explanatory models for crop yield. Plants were grown under field conditions at Ithaca, N.Y. (soil was a fine, illitic, mesic, Glossaquic Hapludalf) and Gainesville, Fla. (soil was a loam‐siliceous, hyperthermic, Grossarenic Paleudalf). To determine the influence of morphological position on individual seed mass, rate and timing of dry matter accumulation of individual seeds at various positions on individual plants were determined from detailed observations of the initiation and termination of seed growth. multiple linear regressions of final individual seed mass on duration and position variables did not consistently account for the variation in seed size. Also, the rate of seed growth was not consistently related to easily observed properties of the plants. No pattern was identified upon which an explanatory model of seed yield could be based. The degree of compensation between mean mass per seed and seed number was determined for individual plants within a cultivar. When individual plants were first grouped according to total plant mass, mean mass per seed was negatively correlated with seed number. Estimates of component compensation which do not take into account the variation in plant size are likely to underestimate the degree of negative correlation.
Yield and Nutrient Utilization Efficiency of Irrigated Corn1
Authors: Rhoads F. M. , Stanley R. L.
Published: July 2010

The concept of a critical concentration of each nutrient in plant tissue, below which poverty adjustment occurs and above which luxury consumption takes place, suggests a quantitative relationship between total uptake of each nutrient and yield in the range of poverty adjustment (RPA). The purpose of this investigation was to determine the relationships between yield of two hybrids of irrigated corn (Zea maysL.) at two populations (60 000 and 90 000 plants/ha) and each of the following variables: g/kg of N, P, and K in the tissue, and total uptake of N, P, and K 4 weeks after silking. Five levels of fertilization of (N‐P2O5,‐K2O) were applied to Pioneer brand hybrids ‘3369A’ in 1977 and ‘3368A’ in 1978 on a Ruston loamy fine sand (fine‐loamy, siliceous, thermic Typic Paleudult). The N‐P2O5K2O ratio was constant at 15‐10‐15 for all treatments. Nitrogen levels were 0, 1, 2, 3, and 5 kg/1000 plants with P and K at the above ratio. Irrigation was applied to recharge the plow layer when soil‐water suction reached 0.02 MPa at the 15‐cm depth. Maximum yields for 60000 plants/ha were 12.7 Mg/ha in 1977 and 10.4 Mg/ ha in 1978. At 90000 plants/ha, maximum yields were 14.5 Mg/ha in 1977 and 9.8 Mg/ha in 1978. Grain yields were significantly correlated with g/kg of N in tissue and total N uptake each year. Lower yields in 1978 were partly attributed to hybrid differences because ‘3368A’ had as high as 0.3 barren stalks at the 90 000 plants/ha population. Nutrient utilization efficiency (NUE) for each nutrient can be expressed without units as grain yield divided by total nutrient uptake. The NUE for N remained within a narrow range (61 to 67) in the RPA regardless of yield and population where the number of barren plants was not significant. Values of NUE for P and K reached maximum levels in the RPA.
Optimum Spacing of Preplant Bands of N and P Fertilizer for Winter Wheat1
Authors: Maxwell T. M. , Kissel D. E. , Wagger M. G. , Whitney D. A. , Cabrera M. L. , Moser H. C.
Published: July 2010

In previous field studies a 46 cm spacing of preplant bands of N and P fertilizer has caused uneven growth of winter wheat (Triticum aestivumL.), with better growth immediately atop the preplant bands. Narrower spacing of fertilizer bands could improve plant growth uniformity and grain production by winter wheat. The objective of this study was to evaluate N‐P fertilizer band spacing on wheat growth and grain yield. The effect of P band spacing on fertilizer P uptake from a preplant band was studied in the greenhouse with winter wheat. Phosphorus uptake from the fertilizer band was influenced by the lateral distance from the wheat row to the P band at 33 days after planting. By 40 days after planting, however, uptake of fertilizer P was the same from bands placed 0, 10, and 20 cm from the wheat row, while P uptake was significantly less from the band placed 30 cm from the row, apparently due to another row of wheat shielding the fertilizer P from uptake. Field studies consisting of combinations of spacings of preplant bands (25, 38, and 50 cm) and rates of P fertilizer (0,6, 12, and 24 kg/ha), all with 84 kg N/ha, were conducted on winter wheat. All treatments were deep‐placed preplant band applications of liquid ammonium polyphosphate (APP, 10‐15‐0) and anhydrous ammonia (82‐0‐0). Wheat was drilled perpendicular to the direction of the preplant band application. Early season growth of winter wheat increased with increasing P rate and by decreasing the distance between preplant bands. Final grain yield, however, was influenced only by P rate, and not by P band spacing. Plant samples taken from 12.5 cm of drill row centered over the band and 12.5 cm of drill row centered between preplant bands of each treatment indicated differences between those areas in dry matter production, P uptake, spike density, and grain yield due to P rate and band spacing. Thus, more uniform growth resulted from the closer band spacing of 38 and 25 cm which could result in higher grain yields under optimum wheat production conditions.
Influence of N, P, and K Fertilization on Yield and Mineral Composition of Native Bluejoint Grass on the Lower Kenai Peninsula, Alaska1
Authors: Laughlin Winston M. , Smith Glenn R. , Peters Mary Ann
Published: July 2010

Domestic grasses are difficult to establish and maintain in the Caribou Hills of the lower Kenai Peninsula in Alaska. Thus this 8‐year study sought to determine native bluejoint [Calamagrostis canadensis(Michx.) Beauv.] response to varying N, P, and K fertilization rates applied annually and stand persistence when two cuttings were made each growing season. A 4 × 22factorial experiment with four N rates (67,134,201, and 268 kg N/ha) and two P and K rates (84 and 168 kg P/hq 93 and 186 kg K/ha) was established on Kachemak silt loam (thixotropic over loamy, mixed Typic Cryandept) at 366 m elevation. Concentrations of NO3−N, total N, P, K, S, Ca, Mg, and Si in the plants were determined and uptake of these constituents calculated, During this 8 years with two annual harvests and with fertilization the bluejoint stand became more dense. Each increasing N rate through 134 kg/ha generally increased the annual yield. Concentrations of N03−N and total N in both cuttings and annual N uptake were increased by each increasing N increment while the Si concentration of each cutting was depressed. Significant yield interaction between N and K occurred with greater response to N or K at the higher rates of the other. Application of P increased forage yield, P, Ca, and Mg concentrations, and P, K, S, Ca, and Mg uptake. Doubling the P rate further increased these values. Potassium application increased yield, K concentration, and P, K, and S uptake. Doubling the K rate increased the yield at higher N rates and decreased Ca, Mg, and Si concentrations and uptake. Ranchers in the lower Kenai Peninsula area of Alaska can now be assured native bluejoint can be the most important forage grass to provide supplemental winter livestock feed. Persistent high yields can be maintained with less cost than with any other presently known forage.
Yield and Yield Components of ‘Braxton’ Soybeans as Influenced by Irrigation and Intrarow Spacing1
Authors: Ramseur E. L. , Quisenberry V. L. , Wallace S. U. , Palmer J. H.
Published: July 2010

Yield and yield components of ‘Braxton’ soybeans [Glycine max(L.) Merr.], Maturity Group VII, were measured for differing irrigation regimes and intrarow spacings. Soybeans were planted in 0.91 m rows in mid‐May, 1980 and 1981 on a Cecil sandy loam soil (clayey, kaolinitic, thermic Typic Hapludults). Prior to the V3 growth stage, plots were thinned to achieve intrarow spacings of 61,76,102, 152,305, and 457 mm in 1980 with spacings of 43 and 51 mm added in the 2nd year. Soil water regimes were full‐season irrigation (FSI), irrigation beginning at bloom (BI), and no irrigation (NI). Beginning at R4, plants from a 0.5‐m section of row were removed at 10‐ to 14‐day intervals for determination of seed growth rate and effective filling period. Yield components (pod number, seed number, seeds per pod, and single seed weight) were determined at R7 or maturity. Final seed yields were determined by harvesting bordered rows following end trimming. Seed yields for the 2 years, averaged over all spacings, were 3023,2876, and 1322 kg/ha for the FSI, BI, and NI higation treatments, respectively. While yields were increased significantly with irrigation, no significant difference in yield was measured between FSI and BI treatments. Yields among plant spacings were not significantly different for any irrigation treatment either year with the exception that the yield of the 457‐mm spacing of the BI treatment was significantly reduced in 1981. Seed number was highly correlated with seed yield, whereas single seed weight was not significantly correlated with yield. Increases in seed number under the irrigation treatments were due to increases in both pod number and seed per pod. Seed growth rate was increased and effective filling period was decreased by irrigation. We concluded that intrarow spacings up to 457 mm had little influence on yield. Even though rainfall was low during vegetative growth prior to bloom in both years, full‐season irrigation gave no yield advantage over bloom irrigation.
Postemergence Sprayer with Adjustable Width Row Shields1
Authors: Michel J. A. , Fornstrom K. J. , Borrelli J. , Jackson G. D.
Published: July 2010

A postemergence sprayer with adjustable width row shields was designed and constructed to apply nonselective herbicides between the crop rows while shielding the emerged crop. An over‐the‐row spray boom is mounted beneath the row shields for banding selective herbicides over‐the‐row. The implement was used successfully in no‐tillage corn (Zea maysL.), dry beans (Phaseolus vulgarisL.), and sugar beets (Beta vulgarisL.).
Cation Composition of Tall Fescue Forage as Affected by K and Mg Fertilization1
Authors: West J. W. , Reynolds J. H.
Published: July 2010

Grass tetany has been observed in cattle grazing cool‐season grasses during the late winter and early spring in the southeastern USA. It has been suggested that Al is involved when this problem occurs on wet sites. Tall fescue (Festuca arundinacea Schreb.) experiments were located at Knoxville (2 years) and Chapel Hill, Tenn. (1 year) to determine fertilizer effects on K, Mg, Ca, and Al concentrations of forage grown on soils subject to flooding. The soils were Lindside loam (fine‐silty, mixed, mesic Fluvaquentic Eutrochrepts) and Roellen silty clay loam (fine, mixed, thermic Vertic Haplaquolls). Treatments consisted of a control and fall applied Sul‐Po‐Mag (2 MgSO4 • K2SO4), Epsom salts (MgSO4 • 7 H2O) + potassium sulfate (K2SO4), Epsom salts alone, or potassium sulfate alone to supply 112 kg Mg and/or 181 kg K ha−1. The forage was sampled from February through early May while these soils were usually saturated with water and at some times while there was water standing on the surface. Magnesium fertilization had little effect on forage Mg while K fertilization usually increased forage K. As growth increased, forage K increased in early spring. Equivalent ratios of K/(Ca + Mg) closely followed trends of forage K and increased potential for tetany but remained below 2.2. Magnesium concentrations remained low (< 2 g kg−1) in the forage through early May. Aluminum and Ca concentrations were usually unaffected by fertilization treatments. There was no apparent benefit from fertilizing these soils with Mg sources. Concentrations of Al dropped considerably when the plant growth was not close to the wet soil surface and when standing water was not present. Apparently, soil Al adhered to the leaves in contact with wet soil or standing water since Al uptake through the roots would be very limited with the soil pH about 6.0.
Distribution of 15N‐Depleted N in Protein Fractions of Rice as Affected by Placement and Timing of N Fertilizer1
Authors: Patrick W. H. , Reddy K. R. , Mulbah Charles
Published: July 2010

Both the quality and quantity of increased protein resulting from fertilization of grain crops are important considerations in evaluating the effects of N fertilization. A field experiment in which 15N‐depleted N fertilizer was applied to lowland rice (Oryza sativa L.) growing on Crowley silt loam (fine, montmorillonitic, thermic Typic Albaqualf) using different methods and times of application showed that total protein content could be increased, especially by late‐season application, but that little effect on protein distribution was obtained. Late‐season application resulted in a larger amount of fertiliizer N being present in the glutelin fraction but with no apparent effect on the more important water‐soluble albumin fraction.
Nitrogen Fixation in Soybeans: An Evaluation of Measurement Techniques1
Authors: Vasilas B. L. , Ham G. E.
Published: July 2010

Accurate estimates of N2fixation by soybeans [Glycine max(L.) Merr.] are needed to evaluate specific interactions between Rhizobium, legume host, and environment. This study compares Kjeldahl‐N, isotope dilution, and ‘A’‐value techniques in the estimation of N2fixation by field‐grown soybeans receiving different levels of soil N. Experiments were conducted in 1979 and 1980 at Becker (Alfic Udipsamment) and Rosemount (Typic Hapludoll), MN. After planting but before emergence, 15N‐labeled (NH4)2SO4, was surface applied in solution at rates of 5, 20, and 100 kg N/ha in 1979; and 10 and 100 kg N/ha in 1980. A non‐nodulating soybean line was used as the control plant. Plant samples for N and 15N analyses were collected at full bloom, full pod, and full seed at Becker; and at full bloom, beginning seed, and physiological maturity at Rosemount. Combined N had little or no effect on N accumulation, vegetative production, nor grain yields of nodulating plants. Percentagewise, N fertilizer utilization in general was similar by nodulating and non‐nodulating plants and tended to increase as fertilizer rates increased.

Although rarely statistically different, ‘A’‐values consistently produced the highest and the isotope dilution technique the lowest estimates of N2fixed. Even under conditions of very low soil N availability, there was excellent agreement between the difference method and the isotope dilution technique. These two methods produced essentially the same values under conditions of low soil N and high fertilizer N (Becker, 100 kg N/ha). At the lowest level of applied N, N2fixation, measured by isotope dilution, contributed approximately 77 and 48% of total plant N at Becker and Rosemount, respectively. Maximum N2‐fixation values of 198 and 167 kg N/ha were achieved at Becker and Rosemount, respectively.
Degradation of Potassium Hydroxide‐Treated ‘Coastal’ Bermudagrass Stems at Two Stages of Maturity1
Authors: Spencer Roland R. , Akin Danny E. , Rigsby Luanne L.
Published: July 2010

The highly lignified and rigid stem tissue of grasses form a formidable barrier to digestion and physical destruction in the rumen of the animal. Alkali treatment has been shown to increase the digestibility of many feeds. The objective of this research was to compare the effect of potassium hydroxide treatment on the physical structure and on the degradation of specific tissues by rumen microorganisms in ‘Coastal’ bermudagrass [Cynodon dactylon(L.) Pers.] stems. Scanning electron microscopy was used to study the relative extent of in vitro cell wall digestion of stems at 6, 24, and 48 h for two stages of maturity. The less mature top stem (TS) was taken from the upper first or second internode while the more mature bottom stem (BS) was taken from the lowest internode above the root. Potassium hydroxide treatment disrupted tissues and caused a swelling of the vascular, sclerenchyma, and epidermal cells. Alkali treatment appeared to break down the bonding in the intercellular layer allowing this material to be degraded by the rumen microorganisms. Similar material in untreated tissues was resistant to microbial attack. Untreated TS were degraded to a greater extent than untreated BS. This difference occurred in parenchyma tissues, of which more cells gave a positive reaction for lignin with the chlorine‐sulfite test in the more mature BS than in TS. Potassium hydroxide treatment increased the disruption of both TS and BS, resulting in a fragile residue, but the TS was more degraded than BS. However, even after alkali treatment and microbial degradation, epidermis, sclerenchyma ring, and disrupted vascular cells were recognizable structures in the residue. The TS was 19% more digestible than the mature BS both before and after alkali treatment. The treated TS and BS's digestibility was increased by 33% over the untreated material.
Effects of N and Seeding Rate on Grass‐Legume Mixtures on Coal Mine Spoils: Biomass Production, Soil Factors, and N2 Fixation1
Authors: Yamanaka K. , Holl F. B.
Published: July 2010

The importance of N2‐fixing legume species in colonization and the development of stable ecosystems on reclaimed mineral spoils has long been recognized. In greenhouse experiments on coal mine spoils some of the factors affecting early plant performance have been evaluated. Applied N was rapidly taken up by plants or leached from the spoil material, such that N would be a limiting factor under similar field conditions. Total biomass production increased with increasing grass seeding rates and at high N fertility while N2 fixation was depressed at higher grass seeding rates and with high N fertility. In the same treatments, a significant (P < 0.01) grass − fertilizer interaction was reflected by an observed decrease in legume biomass. Changes in aboveground total biomass and N2 fixation were related to changes in the legume component and were largely independent of soil N. Optimum biomass production and N2‐fixing activity were obtained by a treatment combination of 17.5 kg/ha grasses, 30 kg/ha legumes, and 50 kg/ha N.
Tillage Modifications of Dry Edible Bean Root Colonization by VAM Fungi1
Authors: Mulligan M. F. , Smucker A. J. M. , Safir G. F.
Published: July 2010

Soils compacted by excessive secondary tillage and traffic restrict the growth and function of plant root systems. The influence of soil compaction on root and the symbiotic vesicular‐arbuscular mycorrhizal (VAM) fungal associations is essentially unknown. The VAM fungal colonization of dry edible bean (Phaseolus vulgaris L.) roots was investigated on Aeric Haplaquept clay, Typic Hapludalf loam, and Typic Haplaquoll sandy loam soils. Three cultivars were subjected to secondary tillage and traffic treatments on several field experiments. The influences of soil porosity, bulk density, depth and type on the colonization of dry edible bean roots by VAM fungi were characterized 45 days after planting. Excessive secondary tillage and traffic increased the bulk densities of all soil types, decreased plant growth and root development. Colonization of dry edible bean root systems was a function of soil type and decreased with increasing secondary tillage and depth within the soil profile. Dry edible bean cultivars having vigorous root systems which penetrated below the Ap horizon of compacted soils maintained high levels of colonization by VAM fungi. Roots of the cv., Seafarer, which are susceptible to both soil compaction and root rot diseases, had the lowest amount of colonization when growing below the Ap horizon.
Self‐Burial of Wild Oat Florets1
Authors: Somody C. N. , Nalewaja J. D. , Miller S. D.
Published: July 2010

Survival of wild oat (Avena fatua L. and A. sterilis L.) florets is greater if the florets overwinter below the soil surface. Therefore, field experiments were conducted to determine wild oat floret selfburial (burial without tillage) as affected by environment and floret characteristics at Fargo, ND in 1978 and 1979. Soil cracking was necessary for self‐burial. Self‐burial was less on Spottswood sandy loam (fine‐loamy over sandy, mixed pachic Udic Haploborolls) than Fargo silty clay (fine, montmorillonitic, frigid Vertic Haplaquolls), which cracked more than the sandy soil. The geniculate awn was necessary for maximum wild oat floret self‐burial. Self‐burial did not require rain and was not impeded when straw was present on the soil surface. Florets of A. sterilis Accession 278, characterized by a slender awn approximately 2.5 cm long with no bend, were less effective at self‐burial and lateral movement along the soil surface than florets of Accessions 318 and 9, both characterized by a longer thick awn with a distinct bend. Avena sterilis Accession 318 had 73% self‐burial even with the primary and secondary florets connected. Awn length and thickness and floret length of 1200 wild oat accessions were variable, but 98.5% of the accessions had florets with a distinctly bent awn.
Heat Tolerance of Kentucky Bluegrass as Influenced by Pre‐ and Post‐Stress Environment1
Authors: Wehner D. J. , Minner D. D. , Dernoeden P. H. , McIntosh M. S.
Published: July 2010

An understanding of the natural variation in heat tolerance of Kentucky bluegrass is needed to develop predictive models for stress tolerance. The variation in heat tolerance of ‘Adelphi’ Kentucky bluegrass (Poa pratensis L.) over the growing season and the effect of recovery environment on the perceived heat tolerance of the plants was determined. Field‐grown plants (Chillum silt loam, fine‐silty, mixed, mesic Typic Hapludults) were exposed to heat stress on 11 dates over two growing seasons by immersion in a water bath for 30 min at either 42,44, or 46 °C and then placed in either a greenhouse, or one of two growth chamber environments (35/22 or 22/15 °C day/night temperature) for a 2‐week recovery period. The dry weight of the stressed plants expressed as a percentage of the controls (recovery weight) was used as a measure of heat tolerance. Heat tolerance increased from May to July and then decreased from August to October. A significant relationship existed between heat tolerance, daylength (D) and average low temperature (LT) for the sampling dates (y − 128.65*D − 5.67*D2 − 14.46*LT − 0.49*LT2 + 2.21*D*LT − 743.86, R2 = 0.95, P = 0.003). Recovery weights for plants in the greenhouse were not significantly different from recovery weights for plants in either of the other two recovery environments on 10 of the 11 sampling dates.
Dinitrogen Fixation by Soybeans in Alabama1
Authors: Thurlow D. L. , Hiltbold A. E.
Published: July 2010

The contribution of symbiotic N2 fixation to total N and yield of soybeans [Glycine max (L.) Merr.] ranges widely among soils and cultural conditions. Utilization of nonnodulating soybean isolines and 15N‐dilution techniques has provided estimates of fixation in indeterminate cultivars on soils of relatively high N supply. Few estimates are available, however, for determinate soybeans on low N soils of the southeastern United States. This work compared the N assimilation of ‘Lee’ soybean with that of its nonnodulating isoline (N‐N Lee) at 10 locations in Alabama over an 8‐year period. Nitrogen accumulations by higher yielding cultivars were also determined. Dinitrogen fixation was estimated as the difference in the amount of N contained in N‐N Lee and Lee or other fixing cultivar. One approach considered N in harvested beans only while another approach involved total N in aboveground plant material at physiological maturity. Results showed that Lee soybeans grown in Alabama without irrigation but with rainfall sufficient for yields exceeding 1640 kg ha−1 fixed an average 172 kg ha−1 of N, while maximum yielding cultivars fixed 217 kg ha−1 of N in aboveground plant material. The estimate for midwestern soybeans of 40% of plant total N derived from the atmosphere is too low for Alabama soybeans, where 70% or more is obtained by fixation.
Effect of Soil Temperature and Inoculum Rate on the Recovery of Three Introduced Strains of Rhizobium japonicum1
Authors: Kvien C. S. , Ham G. E.
Published: July 2010

In order to determine the effect of soil temperature on inoculum recovery within soybean [Glycine max (L.) Merr.] nodules, an experiment consisting of four soil temperatures (15, 20, 25, and 30 °C), four soybean lines (Hodgson, Steele, ISZ.7, and 257.428), four inoculation rates (0,3 × 107, 1.5 × 108, and 3.0 × 108 cells/pot) and replicated four times was conducted in a controlled environmental chamber. Single strain inoculants of USDA 110, 138, and 140 on peat base carrier (l08 rhizobia/gram of peat) were mixed and added to each pot at the time of planting. Plants were then grown for 6 weeks. Soil temperature affected plant and nodule growth as well as the recovery of strains of Rhizobium. Plant heights, when averaged over four soybean genotypes, were 12, 15, 45, and 55 cm for soil temperatures 15, 20, 25, and 30 °C, respectively. Plant dry weight, nodule number and nodule fresh weight increased with increasing temperature until a maximum value was reached at the 25 °C soil temperature. Recovery of introduced strains of R. japonicum 110, 138, and 140 was dependent on soil temperature and inoculum rate. Introduced strains of R. japonicum 110 and 138 showed their highest recovery rates at the 15 and 30 °C soil temperatures. At the 20 °C soil temperature recovery of strains 110 and 138 were significantly lower for the cvs. Hodgson and Steele than for the genotypes 257.428 and ISZ.7. The indigenous rhizobia were most difficult to displace at 20 °C. Strain 140 was a poor competitor throughout the entire experiment.
Effect of Slope Position on the Microclimate, Growth, and Yield of Barley1
Authors: Whitman C. E. , Hatfield J. L. , Reginato R. J.
Published: July 2010

Analyses of the relationship between microclimatic data, yield and growth response usually have been conducted utilizing data collected on level terrain and in small experimental plots. A field study was conducted on 290 ha of undulating topography of a Sehorn‐Balcolm complex soil (Entic Chromoxeret and Typic Xerochert) near Dunnigan, CA (38°48′N 121°58′W) during 1977‐78 to evaluate the effect of slope position and microclimate differences on the growth and yield of barley (Hordeum vulgareL. cv. Briggs). The crop was planted on 3 to 9 Dec. 1977 at 112 kg ha−1density in a 0.15‐m row spacing. Sixteen sites were selected in the field prior to planting ranging from level to 36% slope with aspects from north‐ to south‐facing slopes. At each site twice‐weekly measurements were made of plant growth, i.e., height, number of green leaves, leaf area, number of tillers, dry weight, and phenological stage, on 10 randomly selected plants. Yield and all yield components were measured on 20 1‐m2samples at each site at the end of the experiment. Microclimatic data were measured at each site. The largest variations in crop development occurred prior to jointing and after anthesis. Both drainage and irradiance had large effects on plant growth, exhibited through differences in plant height, maximum leaf area, tiller survival, green leaves per plant, tillers per plant, relative growth rate, and dry matter production. A linear relationship was found between dry weight at the end of the season and intercepted radiation with a slope of 1.28 g MJ−1. Dry matter production and yield were affected by irradiance and drainage. The date of 50% heading was inversely related to the final yield and suggested that delayed flowering was detrimental to grain production in the dryland conditions of the Central Valley.
Estimation of Spring Wheat Grain Dry Matter Assimilation from Air Temperature1
Authors: Bauer Armand , Frank A. B. , Black A. L.
Published: July 2010

Modelers and forecasters of crop growth and yield would benefit from a meterologically based index that precisely describes postanthesis development of spring wheat (Triticum aestivumL.). Five field trials over a 3‐yr period were conducted on Williams loam (fineloamy typic Argiboroll) in which grain dry matter assimilation was measured in hard red spring wheat cultivars grown under different management practices. The measured parameters were regressed on cumulative growing degree‐days (GDD), base temperature 0 °C, and days (DAYS) after anthesis. Over the grain yield range 1488 to 3876 kg ha−1, both GDD and DAYS accounted for 93% of the variability in grain dry matter assimilation among all trials. Maximum average kernel number of 21.8 spike−1was attained when 250 GDD had been accumulated or 12 DAYS after anthesis, and maximum average kernel mass of 27.1 mg after about 770 GDD or 35 DAYS. Constantrate assimilation, from 175 to 630 GDD, was 0.049 mg GDD−1kernel−1, and between 9 and 26 DAYS it was 1.08 mg DAY−1kernel−1. With an average of 447 spikes m−2and average kernel number and mass, constant‐rate phase assimilation was 4.77 kg GDD−1ha−1or 104 kg DAY−1ha−1. Among the variable water and N regimes and cultivars, largest differences in assimilation resulted from soil water supply during heading. With < 65 mm available water, constantrate phase assimilation was as low as 0.038 mg GDD−1kernel−1and with > 84 mm as high as 0.066 mg GDD−1kernel−1. The greater constant‐rate assimilation was accompanied by a shorter grain‐filling duration. Filling duration was shorter when available N levels exceeded the amount needed for the highest grain yields than with N levels which increased yields. Cultivar differences in harvest kernel weight resulted from differences in lag phase assimilation rate.