bluuebunny/crossref_metadata_2025 huggingface dataset:
Evapotranspiration by Subirrigated Alfalfa and Pasture in the East Central Great Plains1
Authors: Blad Blaine L. , Rosenberg Norman J.
Published: July 2010

Evapotranspiration (ET) rates from subirrigated alfalfa (Medicago sativa L.) pasture were obtained to provide an estimation of the upper and lower limits of water demand for crops growing in climatic regions characterized by strong advection of sensible heat. Results of this study showed that ET rates were 20 to 25% lower in pasture than in alfalfa. These differences are much larger than any previously reported in the literature.

Advected sensible heat supplied about 20% of the total energy consumed in the latent heat flux (LE) from alfalfa for the entire study and as much as 40% on certain days. In the pasture, however, with few exceptions, sensible heat was generated rather than consumed.
Effect of Soil Water Stress at Various Growth Stages on Soybean Yield1
Authors: Doss B. D. , Pearson R. W. , Rogers Howard T.
Published: July 2010

Conventional irrigation experiments and rainfall distribution‐yield studies have indicated that insufficient water during flowering and pod‐fill stages frequently limits yields of soybeans (Glycine max (L.) Merr.). In this 3‐year experiment, field plot covers were used to control rainfall and water stress was imposed on plants at various stages of growth to determine more specifically the critical periods for irrigating soybeans for maximum yields. Soil water regimes ranged from a limited supply (10% available soil water) to adequate water (50% available) during the entire growing season. More bean production was obtained from water applied after full bloom than earlier. The pod‐fill stage, from August 15 to September 20 for ‘Bragg’ soybeans at Thorsby, Alabama, was the critical time for adequate water for maximum yields. Yields from adequately watered soybeans were 540 to 1,040 kg/ha, or 24 to 55%, greater than where water was limited throughout the growing season. Highest yield obtained under the best water regime was 3,320 kg/ha. Conditions limiting yields were not obvious.
Development and Distribution of the Corn Root System Under Field Conditions1
Authors: Mengel D. B. , Barber S. A.
Published: July 2010

The rate of corn (Zea mays L.) root growth in the field and root distribution in the soil as related to stage of plant growth has not been studied in detail. To obtain more information we measured the length, fresh weight, and distribution of corn roots at time intervals between planting and harvest in 1970 and 1971. The study was made on corn growing on Chalmers silt loam soil at Lafayette, Indiana. Grain yields were 6,160 kg/ ha in 1970 and 11,700 kg/ha in 1971.

Root length and fresh weight increased rapidly for 80 days following planting, remained relatively constant for 14 days, and then decreased rapidly when the plants were in the reproductive stage. A maximum root density of 4.1 cm/cm3 occurred in the 0 to 15 cm zone at 79 days. The lower soil zones reached maximum root density 1 to 2 weeks later than in the 0 to 15 cm zone. Root density in the 0 to 15 cm zone was greater in cores taken midway between plants in the row than at other locations. Maximum root length was 153 cm/cm2 of surface area at 86 days.
Root Development and Growth Response of Corn Following Mulching, Cultivation, or Interrow Compaction1
Authors: Chaudhary M. R. , Prihar S. S.
Published: July 2010

Field studies were conducted to determine the effect of interrow management on root growth and rooting pattern in corn (Zea mays L.) and to relate these with changes in soil environment. Four cultural treatments, 1) control 2) 5‐cm deep postplanting cultivation, 3) 2‐cm thick straw mulch, and 4) interrow compaction, were established on sandy loam and loamy sand soils during 1970 and 1971. Straw mulch and cultivation enhanced root growth in the upper 15 cm of soil and increased the lateral spread of roots both years. The mulch treatment had less roots than the control below 15 cm. The cultivated plants had more symmetric root distribution. Interrow compaction inhibited lateral spread of roots in the surface layers and caused downward growth of roots. At the 5‐cm depth straw mulch reduced the maximum soil temperature by 2.6 C in 1970 and 2.3 to 6.3 C in 1971. Greater lateral spread and enhanced root growth in the surface layers of mulched plots were associated with reduction of soil temperature and reduction of moisture losses and resulted in better plant growth and higher yield.
Prediction of Spring Wheat Yields from Temperature and Precipitation Data1
Authors: Haun J. R.
Published: July 2010

As a consequence of studies indicating that daily plant growth rate can be used to establish specific, numerical, growth‐environment relationships, it has been found that these relationships may be used in the prediction of yields. Design of a prediction system was based on the hypothesis that plant growth rate, as reflected in cumulative growth during the formative portion of plant development, correlated with yield. To insure accessibility of sufficient data, environmental variables were limited to temperature and precipitation because these are generally the only variables published for long periods of time over broad geographical areas. Estimated soil moisture was calculated by the Thornthwaite‐Mather method.

Significant lags were found in plant response to environmental variables. Lengths of lag periods also changed during the season. Thus, two prediction equations were used to accommodate these changes and they were applied to the temperature and precipitation records. Resulting cumulative growth values and data representing pre‐season moisture conditions were used as independent variables on which yield was regressed to provide a prediction equation for yield.

The system, involving two equations for growth prediction and one equation for yield, was tested on unrelated (data not used in the formulation of equations) weather and yield data for major spring wheat (Triticum aestivum L. em. Thell.) production areas in Canada and the U.S.S.R. The close agreement of predicted yields with actual recorded yields indicates that the use of the system is a promising approach for predicting yields and evaluating the influence of temperature and precipitation on yields.
Mn and B Effects on Micronutrients and P in Cotton1
Authors: Ohki K.
Published: July 2010

Interactions involving macro and micronutrients modify plant growth, as indicated by induced deficiencies or toxicities and growth reductions. The objective of this study was to determine the influence of Mn and B and their interactions on micronutrients in leaf tissues of upland cotton (Gossypium hirsutum L.). A 2 ✕ 11 factorial design included two B levels of 35 and 500 µg/liter and 11 Mn levels, varying from 0 to 4000 µg/liter in nutrient solution under greenhouse conditions.

In blade 3, Mn tissue concentration less than the 10 µg/g critical level induced high Zn concentration of 127 µg/g in leaf tissue. As Mn concentration approached the critcial level, Zn concentrations decreased to 33 µg/g and remained constant with increasing Mn to 247 µg/g. Copper concentration was independent of Mn concentration. However, the reciprocal Mn‐Fe relationship was apparent where Mn concentrations of 4 and 247 µg/g were associated with Fe concentrations of 270 and 51 µg/g, respectively. Manganese nutrition had a small but significant influence on P concentrations where P concentrations of 2.37 and 1.84% were associated with Mn concentrations of 8 and 210 µg/g, respectively. The influence of B levels on micronutrient concentration in leaf tissue was not consistent. Low B induced lower Mn concentrations than did adequate B in young and recently matured tissue, whereas no effect of B levels on Mn concentration was evident in older leaf tissue. Low B induced a small but significantly lower Zn concentration in recently matured blades, while no effect of B nutrition on Cu was observed. However, low B induced higher Fe concentrations in old blades than did adequate B.
Turfgrass Wear Tolerance Mechanisms: II. Effects of Cell Wall Constituents on Turfgrass Wear Tolerance1
Authors: Shearman R. C. , Beard J. B.
Published: July 2010

This investigation was conducted to assess the relationship of cell wall constituents of seven cool‐season turfgrass species to wear tolerance. The turfgrass literature contains no data of this nature. The percent total cell wall (TCW), lignocellulose (ADF), cellulose, hemicellulose, and lignin were determined on a gram dry weight and mg/dm2 basis. Species differed significantly in cell wall constituents for both methods of determination. The relative ranking of the species based on the content of various cell wall constituents expressed on a gram dry weight basis was as follows: Cascade chewings fescue (Festuca rubra var. commutata Gaud) > Pennlawn red fescue (F. rubra L.) and Kentucky 31 tall fescue (F. arundinacea Schreb.) > Manhattan perennial ryegrass (Lolium perenne L.) > Merion Kentucky bluegrass (Poa pratensis L.) > Italian ryegrass (L. multiflorum Lam.) > rough bluegrass (P. trivialis L.). However, the species ranked as follows when the cell wall components were expressed on mg/dm2 basis: Kentucky 31 > Manhattan and Merion > Pennlawn and Italian ryegrass > Cascade > rought bluegrass. Cell wall constituents reported on a g/dry wt. basis were not correlated individually to wear tolerance. However, the combined effects of TCW, ADF, cellulose, and lignin accounted for 96% of the observed wear tolerance variation among the seven turfgrass species studied. TCW, ADF, cellulose, and hemicellulose contents expressed as mg/dm2 were significantly correlated individually to wear tolerance. Their combined effects accounted for 97% of the variation in inter‐species wear tolerance. Total cell wall content expressed on a mg/dm2 basis accounted for 98% of the variation in wear tolerance among the seven turfgrass species.

Cell wall constituents were found to increase significantly with plant maturity, with the exception of hemicellulose. TCW increased significantly during the period from July to September, but declined in all species during October. The TCW, ADF, cellulose, hemicellulose, and lignin contents of leaf blades were significantly less than for the leaf sheath for all species.
Reflectant Induced Modification of Soybean Canopy Radiation Balance. II. A Quantitative and Qualitative Analysis of Radiation Reflected from a Green Soybean Canopy1
Authors: Lemeur Raoul , Rosenberg Norman J.
Published: July 2010

This report is one of a series of papers describing reflectant‐induced modification of the canopy radiation balance. Water‐saving effects are expected since net radiation, which is the driving force for evapotranspiration, should be reduced by the reflectant treatment. The experiments were planned to establish reflection patterns over soybeans (Glycine max. [L.] Merr. ‘Amsoy’) at Mead, Nebraska.

This study was undertaken to determine reflection coefficients at various solar elevations and at two values of leaf area index (LAI = 2.5 and 5.5) of a normal, unreflectorized soybean canopy so as to develop a base line against which to evaluate the effectiveness of various factorial treatments of reflectant materials, times and amounts of application. Therefore, net radiation, incoming and reflected radiation (300 to 3,000 nm) and the corresponding energy spectra within the 380 to 1,550 nm wavelength band were measured using a net radiometer, an upright and inverted pyranometer and a spectroradiometer, respectively.

The shortwave reflection coefficient, αs, as well as the coefficients for photosynthetically active radiation α(PAR) and near‐infrared radiation α(NIR) remained nearly constant throughout most of the day, but increased significantly when solar altitude was less than 35°

The dependence of albedo on LAI was a function of wavelength. At medium to high solar elevations α(PAR) decreased with increasing LAI while α(NIR) increased sharply. At lower solar altitudes both α(PAR) and α(NIR) increased with increasing LAI. The radiant energy reflected from the soybean crop showed a strong spectral shift toward NIR wavelengths with the increase in leaf area.
Estimating Evaporation and Transpiration from a Row Crop during Incomplete Cover1
Authors: Tanner C. B. , Jury W. A.
Published: July 2010

In order to model the evapotranspiration (ET) from a crop with incomplete cover, the evaporation (E) is estimated separately from the transpiration (T) since E and T usually do not vary proportionately. Our objective was to develop and test an ET model based on the “potential” ET formula of Priestley and Taylor and ‘potential’ E and T estimates that are consistent with the potential ET estimate. When E is less than the potential E (the falling rate phase), it is estimated by two approaches based on E falling as t½; however, the model assumes transpiration is at the ‘potential’ rate.

ET estimates during cover development of potato (Solanum tuberosum L. ‘Russet Burbank’) for 2 years were compared with lysimeter measurements. The standard error of estimate varied from 0.40 to 0.94 mm/day depending on the method for estimating E. The estimate of cumulative ET for 4 weeks varied from the lysimeter a maximum of 1 cm in 9.7 cm ET.
Planting Corn in Sod and Small Grain Residues with Minimum Tillage1
Authors: Robertson W. K. , Lundy H. W. , Prine G. M. , Currey W. L.
Published: July 2010

High costs of labor, fuel, and machinery; need to conserve moisture; loss of soil from erosion; and desire to double crop are some of the factors considered in the trend towards no‐tillage methods of planting crops.

No‐tillage planting of corn in Pensacola bahiagrass (Paspalum notatum Flugge) sod and small grains such as rye (Secale cereale L.) was compared to conventional planting “rotavating, disking, and planting” for 3 years on Lakeland fine sand (Typic Quartzipsamment).

When Pensacola bahiagrass was treated with paraquat + residual herbicide before planting corn by the notillage method, it recovered quickly and competed with the corn for water and nutrients. Corn (Zea mays L.) planted no‐tillage had lower yields than when conventionally planted, but after corn harvest the bahiagrass growth was adequate for grazing. Adding extra N to the no‐tillage corn increased yields of both corn and grass. Corn under no‐tillage in rye treated with paraquat + residual herbicides generally yielded about the same as conventionally planted corn.

Pensacola bahiagrass when treated with glyphosate in combination with other herbicide was almost all killed and offered little competition to the corn. Forage yield in the fall was only 37% of yield after paraquat‐residual herbicide application.

The effectiveness in controlling broadleaf weeds with atrazine, cyanazine, alachor, linuron, and combinations of these herbicides varied seasonally, but had no significant effect on corn yields. Weed growth at corn harvest was considerably less on the no‐tillage plots; however, after 3 years of continuous no‐tillage corn perennial weeds were beginning to appear while few perennial weeds were observed in the conventionally planted corn.
Comparison of Simulated and Measured Nitrogen Accumulation in Burley Tobacco1
Authors: Zartman R. E. , Phillips R. E. , Leggett J. E.
Published: July 2010

Efficient utilization of N fertilizers by plants is important for scientific, economic, and environmental reasons. The objectives of this experiment were (1) to experimentally evaluate the simultaneous mass flow and diffusion of NO3‐N to tobacco roots and (2) to compare the calculated accumulation of N in tobacco, the root of which was assumed to be a perfect sink for NO3‐N (Model I), or flux of NO3‐N into the root which was assumed to be proportional to concentration of NO3‐N at the root surface (Model II), to measured accumulation of N in Burley tobacco grown under field conditions. Model I overestimated accumulation of N an average of 52%. Model II underestimated accumulation an average of 26%. The proportionality constant, k, assumed by Model II, was found to be 4.27 ✕ 10−7 cm2 sec−1 throughout the growing season, except when moderate plant water stress was experienced by the plant. The data show that the accumulation of N by Burley tobacco was proportional to the concentration of NO3‐N in the soil solution.
Evaluation of Sulfur‐coated Urea (SCU) Applied to Irrigated Potatoes and Corn1
Authors: Liegel E. A. , Walsh L. M.
Published: July 2010

Excessive rates of soluble N fertilizers are sometimes used on irrigated sands in Central Wisconsin to compensate for loss of some of the applied N by leaching. Use of a slow‐release form of N or several small applications of a soluble N fertilizer may eliminate some leaching and subsequent loss of NO3‐N. This study was designed to evaluate these methods of reducing N losses by measuring yield and recovery of applied N by potato (Solanum tuberosum L.) tubers and corn (Zea mays L.) grain. Supplemental N treatments applied each year for 3 years were as follows: 1) urea in a single or split application, 2) SCU impregnated with a wax coating, and 3) SCU with only a sulfur coating.

Recovery of applied N by tubers from a single urea application was extremely low in 1972 due to severe leaching induced by abnormally high precipitation. Slow‐release SCU carriers produced higher yields and N recovery that year because their slow dissolution reduced leaching losses of N. However tuber yields and recovery of N from urea treatments were greater than from SCU treatments in 1973 and 1974 because of reduced leaching those years. In addition, the supplemental N (urea or SCU) for all potato treatments was protected from leaching in 1973 and 1974 by placement of the N into a relatively dry zone of the potato hill.

Corn yields and grain N recovery were similar among carriers of N in 1972 and higher from urea than SCU in 1973 and 1974. The greater recovery of N from urea by corn grain as compared to potato tubers in 1972 apparently was due to the deeper rooting of corn. Furthermore the potatoes received twice as much water by irrigation as compared to the corn.

Oat (Avena sativa L.) forage yields from both trials in 1975 indicated there was greater residual N in SCU plots than urea plots due to incomplete release of urea‐N from SCU. Adequate dissolution of SCU‐N within a single growing season occurred only under severe N‐leaching conditions.
Effect of Rice Straw Incorporation on Rice Plant Growth and Nutrition1
Authors: Rao D. Niranjan , Mikkelsen D. S.
Published: July 2010

Rice (Oryza sativa L.) straw disposal by soil incorporation may have adverse effects on subsequent rice seedling growth from toxic anaerobic decomposition products and temporary immobilization of the soil mineral N. Glasshouse and laboratory studies were conducted to study the problem under conditions of direct sowing of rice.

Samples of a typical rice soil, Sacramento clay, which is a very fine, montmorillonitic thermic Vertic Hapiquall, were collected. Rice straw in amounts of 0, 0.25, and 0.5% was added to soils which were incubated aerobically for 0, 15, and 30 days in a glasshouse plant growth experiment, and for 0 and 20 days in preparation for a laboratory soil incubation experiment. Nitrogen was applied at the rate of 50 ppm in the glasshouse experiment and 50, 75, and 100 ppm in the laboratory study. N was added after aerobic incubation and subsequently rice was grown for 21 days to measure seeding growth effects. The glasshouse experiment with rice cultivar ‘Earlirose’ also evaluated the production of acetic, propionic, and butyric acids, while the laboratory soil incubation experiment was for N transformation data.

The results clearly indicate that when soil and rice straw were not incubated prior to planting rice seedlings, applied N was immobilized, causing inhibition of plant growth and low N content of plants. When rice straw was incubated in soil for 15 to 30 days before planting seedlings, N immobilization was reduced and plant growth was promoted. Nitrogen immobilization was observed to be the principal cause of inhibition of plant growth from added rice straw. Organic acids (acetic and propionic) were produced in amounts considered to be below the toxic concentration of plants. Butyric acid was not found in the soil extracts.
Growth of Subterranean Clover in a Range Soil as Affected by Microclimate and Phosphorus Availability. I. Field Studies1
Authors: Raguse C. A. , Evans R. A.
Published: July 2010

Relationships between microenvironment and phosphorus availability are important to stand establishment and winter growth of introduced annual legumes in California's foothill rangelands.

Ridge, furrow, north‐facing, and south‐facing microsites were established to create variations in light and temperature microenvironments in previously tilled soils of the Sobrante and Las Posas series. An additional microsite treatment, consisting of a simulated range drill seeding, with and without a litter cover, was made on adjacent untilled soil. Phosphorus rates, applied as single superphosphate, were 0, 40, 80, and 160 kg P/ha.

Pellet‐inoculated seeds of subterranean clover (Trifolium subterranean L.) were sown in rows 15 cm apart perpendicular to the microsite ridges, slopes, and furrows.

Soil (1 cm) and air (3 cm above soil) temperatures were monitored hourly with thermistors.

Plant sampling was done at four times from November to March to determine morphological development, plant weight, and percent P per plant. At maturity, remaining plants were sampled to estimate seed production.

Large diurnal temperature differences were associated with microsite treatments and were more pronounced for soil than for air.

Percent P in shoot tissue generally reached highest values in January, indicating that plant growth was restricted more during winter than was P uptake. With warmer temperatures and higher light intensities in February, growth dilution resulted in a decrease in P percentage. Small modifications of microrelief significantly altered the microenvironment, especially soil temperature. Morphological development and plant weight responses were greatest on south‐facing slopes and at the highest P level. Seed production was not influenced by P fertilization.
Effect of Water Stress During Different Stages of Growth of Soybean1
Authors: Sionit Nasser , Kramer Paul J.
Published: July 2010

The effects on yield of controlled water stress applied at various stages of development were studied on two varieties of soybean (Glycine max (L.) Merr.), ‘Ransom’ and ‘Bragg.’ The plants were grown in a controlled environment chamber at 28/17 C with a 9‐hour photoperiod at 450 hlx and an interrupted dark period. Interruption of the dark period was suspended for 7 days to induce flowering. Groups of plants were subjected to water stress during flower induction, flowering, pod formation, and pod filling.

Leaf water potential during stress fell as low as —23 bars, but after rewatering the potential of plants in all treatments returned approximately to normal. Plants stressed during flower induction and flowering produced fewer flowers, pods, and seeds than controls because of a shortened flowering period and abortion of some flowers. Stress during early pod formation caused greatest reduction in number of pods and seeds at harvest. However, yield as measured by weight of seeds was reduced most by stress during early formation and pod filling. Water stress at no stage of growth materially affected the oil or protein content of the seeds.
Root Zone pH Changes and Ion Uptake Imbalances by Triticale, Wheat, and Rye1
Authors: Mugwira L. M. , Patel S. U.
Published: July 2010

Differential pH induced in growth media and the ion uptake imbalances of different cultivars are important criteria of degrees of aluminum tolerance. The objective of this study was to determine if changes in pH of nutrient solutions and soil and anion‐minus‐cation (A—C) uptake from solution can be used to rank cultivars of triticale (X Triticosecale Witt Mack) of differential Al tolerance. Changes in pH induced by 11 cultivars of triticale, wheat (Triticum aestivum L.), and rye (Secale cereale L.) were measured in 1/5‐strength Steinberg solution with initial pH of 4.8 and in Al‐toxic Tatum clay loam subsoil (clayey, mixed, thermic, Typic Hapludults) at different lime rates in a growth chamber. The A—C uptake, pH, and H+ changes were measured for 4 days in a solution containing 1 × 10‐3 M KNO3 plus 2 × 10‐4 M Ca (NO3)2 initially adjusted to pH 4.65. Aluminumtolerant ‘Seneca’ and ‘Atlas 66’ wheats induced significantly higher pH in both solution and soil at low pH values of 3.84 and 4.39 than Al‐sensitive ‘Arthur’ and ‘Morion’ wheats. However, at pH 5.88 Seneca produced significantly higher pH than Atlas 66 and Monon wheats. Aluminum‐tolerant ‘6TA 298’ triticale induced the same pH in solution but higher pH in the soil than the more Al‐sensitive ‘6TA 131’ ‘6TA 385’, ‘6TA 522’, and ‘6TA 203’ triticales except at pH 5.88, when 6TA 298 and 6TA 385 gave the same pH value. Abruzzi and Vitagraze ryes gave similar pH values to Atlas 66 in solution but were less effective in raising the pH of the soil. The A—C accounted for pH changes (r = 0.731**) in solution containing KNO3 and Ca(NO3)2 and there was an approximately stoichiometric relationship between A—C and H+ changes during each of the 4 days without clear separation of the cultivars according to their differential Al tolerances. The pH changes were consistently related to Al tolerance in the Steinberg solution for wheats and in the soil below pH 4.5 for triticales and wheats.
Leaf Reflectance vs. Leaf Chlorophyll and Carotenoid Concentrations for Eight Crops1
Authors: Thomas J. R. , Gausman H. W.
Published: July 2010

Leaf reflectance in the 0.40‐ to 0.75‐μm wavelength interval is influenced primarily by the pigments chlorophyll and carotenoid. However, the literature contains very few references to the relation between reflectance from leaves and their carotenoid content. Our objectives in this study were to determine which of three wavelengths in the visible spectral region best related leaf reflectance to total chlorophyll and carotenoid concentrations, and the relative effect of these pigments on reflectance.

Hemispherical reflectances of single leaves at each of the 0.45‐, 0.55‐, and 0.67‐μm wavelengths for cantaloupe (Cucumis melo L. cv. reticulatus Naud.), corn (Zea mays L.), cotton (Gossypium hirsutum L.), cucumber (Cucumis sativus L.), head lettuce (Lactuca sativa L. cv. capitata L.), grain sorghum (Sorghum bicolor (L.) Moench), spinach (Spinacia oleracea L.), and tobacco (Nicotiana tabacum L.) were regressed on each crop's leaf total chlorophyll and carotenoid concentrations. The crops were grown in sand culture, and their leaf pigment concentrations were varied by supplying N at rates of 14, 28, 84, 140, and 196 ppm to a basic nutrient solution.

Hemispherical reflectance of leaves was inversely related to each crop's leaf chlorophyll and carotenoid concentrations. However, of the three wavelengths tested, the 0.55‐μm wavelength seemed superior for individually relating the two pigments to leaf reflectance. The independent effects of carotenoid on hemispherical reflectance were small and generally not statistically significant, whereas the independent effects of chlorophyll while small were generally significant. The combined effects of these variables were highly significant and accounted for 39 to 95% of the reflectance variability.

This study indicated that even though including carotenoid with total chlorophyll measurements improved the correlation of reflectance with pigment concentration, satisfactory results would be obtained by chlorophyll analysis alone.
Mechanical Scarification of Dormant Wild Rice Seed1
Authors: Oelke E. A. , Albrecht K. A.
Published: July 2010

Wild rice (Zizania aquatica L.), which formerly grew only under natural conditions until the early 1960's, is now being grown as a cultivated field crop. A 3 to 6‐month, post‐harvest seed dormancy hinders the continued development of wild rice as a field crop. Part of this dormancy is due to an impermeable pericarp. Scarification with chemicals to increase permeability has not been successful, and scraping the individual seeds to remove the pericarp above the embryo is too time‐consuming. A small rock polisher was evaluated as a scarification device in this study. Three dehulled seed lots, one from greenhouse‐grown plants and two from field‐grown plants with different harvest dates were used. Samples from each were tumbled with dry crushed granite in the polisher for varying times or scraped with a razor blade to remove the pericarp above the embryo. Laboratory and greenhouse gemination were used to measure the resulting release of dormancy. Seed tumbled in the laboratory for 1 hour gave gemination percentages in water of 44 to 60, depending on the seed lot. Scraped seed gave gemination percentages of 65 to 100 for the corresponding seed lots. Tumbling resulted in less seed injury and required less time than scraping seed. Placing tumbled or scraped seed 1.5 cm deep into soil in the greenhouse before flooding gave an average gemination percentage of only 13 compared to 64 when seed was germinated in water. Transplanting seedlings from scarified seeds germinated in water was more successful than direct planting of scarified seed to establish greenhouse stands. Use of the rock polisher significantly accelerated scarifying wild rice seed with a minimum amount of injury. This method may be adapted to other high moisture seed that requires scarification.
Testing Salt Tolerance Variability Among Tall Wheatgrass Lines1
Authors: Shannon Michael C.
Published: July 2010

The vague symptoms of moderate salt stress on plants and the lack of understanding about the mechanisms that confer salt tolerance have hampered efforts to develop reliable screening procedures for this trait. In the present study a screening procedure was evaluated to determine its usefulness in detecting variation among introductions of tall wheatgrass [Agropyron elongatum (Host) Beauv.]. In greenhouse sand flats, 32 lines tall wheatgrass were established and subjected to stepwise increases in salinity up to 765 meq/liter or until severe leaf damage resulted. The lines were classified into five groups based on relative leaf damage and recovery rates from salt treatment. Repeating the screening procedure on seven each of the most tolerant and most sensitive lines reaffirmed the results of the first screening. Mineral analyses indicated that tolerance was associated with restricted accumulation of Na, Ca, and Cl in the shoots. Proline and soluble sugars contributed to osmotic adjustment at high salinities, but sensitive and tolerant lines did not differ in proline content. This screening technique appears to discriminate between lines with different ion transport properties and different salt tolerances. The sensitive and tolerant lines identified may be beneficial in future breeding and physiological studies.
Evaluation of Peat and Granular Inoculum for Soybean Yield and N Fixation Under Irrigation1
Authors: Bezdicek D. F. , Evans D. W. , Abede Evans B. , Witters R. E.
Published: July 2010

Granular inocula have the potential advantage over peat inocula in ease of handling and application. Further, more total rhizobia can be applied with the granular form. The purpose of this study was to evaluate these carriers for effectiveness in nodulation, N fixation, and yield of soybeans (Glycine max, L. Merr.) in a soil deficient in N. Soybeans were inoculated in the field with peat and granular carriers containing Rhizobium japonicum strains and evaluated for yield, nodulation, and N fixation in a R. japonicum‐free Xerollic Camborthids soil. Maximum yield response from inoculation (less control) was 3,454 kg/ha (51.4 bu/A) in 1975 and 2,547 kg/ha (37.9 bu/A) in 1976. Total N fixed was estimated to as high as 311 and 263 kg/ha in 1975 and 1976, respectively. The proportion of plant N derived from N fixation ranged from 71 to 80%. Estimates of total N fixed based on acetylene reduction were half of those based on total plant N. In general, higher soybean yield and better nodulation were obtained with the granular than peat carriers, although in these instances, higher‐than‐recommended rates of granular carriers were used. Beltsville R. japonicum strains 110 and 138 added as granular inoculum were associated with the highest yields in both years. Strains 110 and 138, in addition to being associated with the highest soybean yield, were more competitive as determined from serological recovery. These studies show that soybeans are capable of fixing over 300 kg/ha of N, an amount which is considerably higher than that reported elsewhere. The data suggest that in soybean‐growing areas where 25 to 40% of the total N is from fixation, the soybean symbiotic N‐fixing system is capable of fixing sufficient N for yields far beyond that now reported. Applying Rhizobium in granular carriers may be superior to peat where more Rhizobium is needed than applying Rhizobium by conventional peat inoculation.
Influence of Intra‐Row Spacing and Cutting Regimes on the Growth and Yield of Leucaena1
Authors: Guevarra A. B. , Whitney A. S. , Thompson J. R.
Published: July 2010

Leucaena (Leucaena leucocephala (Lam.) de Wit) has proven to be a very productive tropical legume, but the factors which control production under intensive management have not been well defined. Thus three harvest frequencies (based on attained plant height), three population densities, and two plant types of leucaena were evaluated at North Kohala, Hawaii (120‐m elevation, Typic Ustropept). Plants of K341 (a shrubby “Hawaiian” type) and K8 (an arboreal “Salvador” type) were grown at spacings of 15 ✕ 50, 30 ✕ 50, and 45 ✕ 50 cm, and harvested when plants attained average heights of 55, 105, or 155 cm. Stem elongation rates and yields were highest during periods of high solar radiation and high night temperature. Selection K341 tended to flower at an early stage, especially at the lower planting densities, with consequent reduction in vegetative growth. Selection K8 increased in height more rapidly than K341 and thereby intercepted more sunlight until about 14 weeks when light interception values were similar at 96%.

Yields increased with less frequent cutting. Total dry matter yields when cut at attained heights of 55, 105, and 155 cm (about 2 1/2, 3, and 4 months growth duration) were 11.9, 16.9, and 20.8 metric tons/ha, respectively. However, the percentage forage fraction was higher under more frequent cutting; averaging 79, 68, and 59% for the same three treatments. Percentage forage fraction also tended to be slightly higher at the highest plant density, since leucaena was unable to compensate for wide spacing by producing more shoots. Plant type, spacing, and cutting treatments did not affect the levels of N or mimosine in the forage fraction (4.3 and 6.7% respectively) or in the stem fraction (1.5 and 0.9%, respectively. K341 yielded nearly 600 kg N ha−1year−1 in the forage fraction while K8 yielded about 500 kg N ha−1year−1.

Dense planting (15 ✕ 50 cm) and cutting when the plants were approximately 1 m in height were desirable management practices considering forage yield, percentage forage fraction, forage quality, flowering behavior, and average cutting frequency (3 months).
Response of Winter Wheat to Date of Planting and Fall Fertilization1
Authors: Knapp W. R. , Knapp J. S.
Published: July 2010

Winter injury of small grains often results in severe yield reductions. This study was conducted to determine how planting date and fall fertilization interact to affect winter survival and performance of winter wheat (Triticum aestivum L.). In 1975 ‘Arrow’ wheat was planted in central New York on eight dates ranging from 21 August to 24 October. In 1976 five plantings were made from 31 August to 14 October. In both years 75 kg/ha of K was disked in and then four fertility treatments were band applied at each planting date. These were 0 N and 0 P, 0 N and 20 kg/ha P, 22 kg/ha N and 0 P, and 22 kg/ha N and 20 kg/ha P. At harvest measurements were taken for grain yield, plant height, grain moisture, test weight, and components of grain yield. Wheat planted in mid to late September had greater winter survival and produced significantly more grain with a higher test weight than did later planted wheat. The effects of earlier planting varied between years because of different weather conditions. Grain moisture content increased with planting delay. Planting after the optimum time decreased the number of spikes per square meter both years. This component was closely related to yield and was an indication of the degree of winterkilling. Planting date had variable effects on the number of kernels per spike and kernel weight. Phosphorus alone or with N significantly increased wheat yields and winter survival. This effect was reflected in an increased number of spikes per unit area and increased kernel weight. Nitrogen alone had little effect on yields when compared to unfertilized wheat; and when N was applied with P the results were similar to those from P alone. Test weight generally increased with P but not with N. Phosphorus also hastened grain maturation, while N had no beneficial effect. Nitrogen also did not increase any yield component. As planting date was delayed, the value of P for increasing winter survival, grain yields, and grain maturation became increasingly important, resulting in significant planting date ✕ fertilization interactions for these characteristics.
Critical Manganese Deficiency Level of Soybean Related to Leaf Position1
Authors: Ohki K. , Boswell F. C. , Parker M. B. , Shuman L. M. , Wilson D. O.
Published: July 2010

Correct interpretation of results from plant analyses depends on many factors which include sampling the appropriate leaf blade for microelement analysis. Although numerous reports conclude that the recently matured leaf should be sampled for tissue analysis, specific information relating concentration of leaf‐blade Mn by leaf position to yield of field‐grown soybean (Glycine max (L.) Merr.) yield has not been reported previously. A 2‐year field study was conducted on an Olustee‐Leefield sand (Ultic Haplaquod‐Arenic Plinthaquic Paleudult) to determine the most ap ropriate leaf on the main axis for tissue analysis. Leaf samples were taken at the R2 growth stage (flower at node immediately below the uppermost node with completely unrolled leaf) from plots treated with 0 to 56 kg/ha Mn. Leaf blades sampled were one (top) down the axis in sequential order through blade five. Relationships between leaf Mn concentrations and seed yield over 2 years showed that critical Mn deficiency levels for blades one through five were 18, 13, 11, 11, and 10 µg/g, respectively. The critical deficiency levels for each leaf position were similar between years.
Agronomic Performance and Protein Content of Fall‐planted Triticale, Wheat, and Rye1
Authors: Bishnoi U. R. , Hughes J. L.
Published: July 2010

Triticale (X Triticosecale Wittmack) is a relatively new grain and forage crop, but no information is available on agronomic performance of this crop relative to wheat (Triticum aestivum L.) and rye (Secale cereale L.) grown in the southeastern U. S. A field experiment was conducted during three growing seasons, 1973–1975, on a Decatur silty clay loam soil (Rhodic Paleudult) to provide comparative data on seven triticale cultivars and one recommended cultivar each of wheat and rye. Results indicated that forage yields of two winter‐type triticales, ‘6TA 131’ and ‘6TA 385’, were equal to that of ‘Winter‐grazer 70’ rye and significantly better than ‘Arthur’ wheat or rye for grain yield. Clipping for forage reduced grain yied 15 to 20%, in intermediate types, 9 to 12% in wheat and winter triticales, and less than 4% in rye. Winter triticales were taller or equal to rye in height and also showed relatively more lodging than wheat and intermediate types. Test weight of wheat was highest. The protein content in dry green forage ranged from 24 to 27% among all the entries. Triticale cultivars averaged 14.4% protein in the whole grain while wheat and rye averaged 13.7 and 13.2%, respectively.
Plant Spacings with Irrigated Cotton1
Authors: Smith C. Wayne , Waddle B. A. , Ramey H. H.
Published: July 2010

The majority of research concerning stand density of cotton (Gossypium hirsutum L.) was conducted several years ago under dryland conditions and deals primarily with lint yield and earliness of a single genotype. Therefore an experiment to compare three cultivars at three stand densities was initiated in 1975. ‘Quapaw’, ‘Rex 713’, and ‘Deltapine 16’ were grown in stand densities of one plant per 6.1, 10.2, and 30.5 cm, which corresponds to populations of 169,841, 101,573, and 33,969 plants/ha, respectively, A split plot design with cultivars as main treatments and stand densities as sub‐plots was utilized with furrow irrigation on a Grenada‐Calloway silt loam soil, a fine, silty, mixed, thermic alfisol.

The cultivars differed in lint yield and boll and fiber properties as expected. Plants spaced 10.2 cm yielded significantly (P<0.05) more lint, 1,109 kg/ha, than plants growing 6.1 cm apart and yielding 954 kg/ha, but did not differ from the wider spacing, which yielded 1,031 kg lint/ha. The low stand density caused significantly later maturity; while the high stand density (6.1 cm spacing) resulted in significantly lower lint percentage and smaller bolls. Fiber elongation was the only character measured in which a significant interaction of density ✕ cultivar was found.

Cotton in central east Arkansas under irrigation should be grown approximately 10.2 cm apart in 96.5 cm rows (101,573 plants/ha). Based on these data, plant genotype does not affect plant response to stand density.
Response of Soybean Cultivars to Planting Patterns1
Authors: Costa J. A. , Oplinger E. S. , Pendleton J. W.
Published: July 2010

Since soybean [Glycine max (L) Merr.] acreage continues to increase in the higher latitudes of the world the objective was to obtain agronomic information on the effect of inter and intra‐row spacings on several of the most widely grown, early cultivars in America. Ten soybean cultivars differing in maturity (Group 0 through II) and growth characteristies were grown in two row spacings (27‐cm and 76‐cm) and varying populations (132,000 to 741,000 plants/ha) for 3 years in field trials on Typic Arguidolls fine silty; mixed mesic soil near Madison, Wis.

Planting soybeans in 27‐cm rows vs. more conventional 76‐cm rows showed an average seed yield increase of 21% over all years, populations, and cultivars. All cultivars produced higher seed yields in narrow row spacings. The three early cultivars (Group O Maturity) generally exhibited a greater yield response (+27%) to narrow row spacings than did cultivars in Maturity Groups I and II (+19%). However, the later maturing cultivars generally produced the highest yields over all row spacings, plant populations and years. Varying the intra‐row plant spacing did not significantly affect seed yields. Increasing plant populations decreased the number of branches per plant and increased lodging, seed weight, and LAI. While the LAI increased as plant population increased in both the narrow and wide rows, no correlation existed with grain yield. Increasing the plant population in each row spacing increased the height of the lower pod by a range of 40 to 50%.

The availability of new varieties with improved lodging resistance and herbicides with greater selectivity may lead to an accelerated acceptance of narrow row soybean production systems to capitalize on the increased yield potential in the northern growing regions.
An Energy‐Crop Growth Variable and Temperature Function for Predicting Corn Growth and Development: Planting to Silking1
Authors: Coelho Dirceu T. , Dale Robert F.
Published: July 2010

Weather effects on crop growth, development and yield have to be quantified to interpret agronomic experiments properly and to encourage use of weather and climate information in agricultural planning and the assessment of crop yield potentials. The main objective of this research was to develop a single environmental index for use in identifying the effects of the three most important weather variables on crop production: light, temperature, and moisture. An Energy‐Crop Growth (ECG) variable was generated and tested to predict the increase in dry matter of total above‐ground corn (ZeA mays L.) plants from the time the growing point rose above the soil surface to silking. The Crop Growth Rate (CGR) was measured by destructively sampling corn plants in the field every few days in a randomized, complete‐block design, where treatments represent successive harvests in time (weather). Early and late plantings of a full‐season corn hybrid at 62,000 plants/ha on a Typic Argiaquoll at West Lafayette, Ind. from 1972 to 1974 were used to develop the relations. The ECG variable is defined as the daily product of the solar radiation intercepted by the crop canopy, a moisture stress factor and a temperature function (FT). For each unit of ECG, CGR increased about 547 kg/ha from the time the growing point rose above the soil surface to about 10 days before silking, after which it decreased to about 355 kg/ha per ECG until silking. These CGR on ECG relations were tested with independent experimental data for 1970 and 1971 to find a 1:1 relation between the predicted and measured plant dry weights. The accumulation of the temperature function alone (∑FT) was used to define the corn phenology periods examined in the development of the CGR‐ECG relations. Maximum and minimum temperatures at the 10‐cm depth in bare soil were used to calculate FT from planting to ∑FT = 12, and then air temperatures to silking. The ∑FT from planting to silking for full‐season corn hybrids averaged 37.4 ± 1.2 for 12 planting‐years, 1969 to 1974. The ∑FT method was tested for its precision and accuracy, relative to that of the modified growing degree day method (∑MGDD), by predicting dates that 50% of the corn acreage had silked in the West Central Crop Reporting District in Indiana, 1962 to 1978. The absolute error between actual and predicted silk dates averaged 3.1 ± 2.2 days using ∑FT, slightly better than the 4.1 ± 2.4 days predicted with ∑MGDD. The ECG, timed with ∑FT offers definite Potential for defining weather effects on corn growth with a single variable.