bluuebunny/crossref_metadata_2025 huggingface dataset:
Straw and Tillage Management Practices in Soybean‐Wheat Double‐Cropping1
Authors: Sanford J. O.
Published: July 2010

Managing straw residue in wheat (Triticum aestivum L.)‐soybean [Glycine max (L.) Merr.] double‐cropping systems can be a problem, and many management systems are currently being used. Type of tillage used is, to some extent, determined by the straw management practice. In this study, five tillage‐straw management practices were studied on Brooksville silty clay (fine, montmorillonitic, thermic Aquic Chromudert) for 4 years. Only 3 years' data are reported, however, since all treatments failed 1 year because of extreme drought. Objectives were to determine effects of tillage‐straw management practices on (a) stand establishment, growth and yield of double‐cropped soybeans, (b) surface soil organic matter content, and to (c) compare costs and net returns of the wheat‐soybean systems and the monoculture soybeans.

In 1 of 3 years when rain did not soon follow planting, preparing the soil by disking, whether the straw was burned or not, resulted in reduced germination and growth. During 1 year, germination was adversely affected when the straw was shredded and left on the soil surface. Yields were highest and most consistent when soybeans were no‐till seeded into the burned stubble, but these yields did not differ from systems where straw was burned followed by conventional tillage or where straw was shredded followed by no‐till planting. The average soybean yield was 29% less for the best double‐crop practice than for monoculture soybeans (1,370 kg/ha vs. 1,927 kg/ha). Wheat yields averaged 3,384 kg/ha and were not affected by the tillage‐straw management practices. Excluding a year in which all double‐crop systems failed, all double‐crop systems except where the wheat straw was incorporated in land preparation gave greater economic returns than monocrop soybeans. The double‐crop system in which straw was burned followed by no‐till seeding and cultivation, gave the greatest average net return.
Potato Irrigation Requirements in a Hot Climate Using Sprinkler and Drip Methods1
Authors: Shalhevet J. , Shimshi D. , Meir T.
Published: July 2010

Potato (Solanum tuberosum L.) is a heat‐ and drought‐sensitive crop, which in hot climates usually requires large water applications for optimum production. Irrigation water in Israel is both limiting in quantity and high in price; thus it is critical to know the water requirement of the crop, as well as how to improve irrigation efficiency. Field experiments were conducted in the Negev (arid) region of Israel on a Typic Camborthid soil to determine the water production functions of potatoes (‘Desiree’) under drip and sprinkler irrigation. Irrigation treatments were based on Class A pan evaporation. The linear production functions relating total yield in metric ton ha−1 to seasonal water application depth (W) in cm were, for sprinkler irrigation: Y = ‐23.5+1.19W, and for drip irrigation: Y = −12.8+1.14W. Similar total maximum yields were obtained with about 8 % less water with the drip as with the sprinkler method (not statistically significant). A single production function for both methods described the yield of marketable tubers: Y = −40.0+1.28W. These functions apply in the relative water application range (water applied over Class A pan evaporation) of 0.3 to 1.0, at which point the function reaches a plateau. Yield was reduced by 12% as soil water potential in the 0 to 0.6 m depth increment changed from −20 to −29 J kg−1 for sprinkler irrigation. Under drip irrigation the soil could dry to −40 J kg−1 without yield reduction, as long as the water supply was adequate. This was explained by the higher root concentration under drip than under sprinkler irrigation.
Establishment and Nodulation of Arrowleaf Clover1
Authors: Rich P. A. , Holt E. C. , Weaver R. W.
Published: July 2010

We need information on effects of planting depths and inoculation methods on stand, nodulation, and early plant development for establishing temperate, small‐seeded annual legumes. Arrowleaf clover (Trifolium vesiculosum Savi ‘Yuchi’) plantings from uninoculated and water or commercial sticker inoculated seed were made at depths of 0, 10, 25, and 40 mm with and without irrigation immediately following planting, on a Udertic Haplustoll soil. Seedling and nodule numbers, and biomass (plant top and root weights) were determined in eight environmental periods. Regression testing and curve fitting of unequal planting depth increments and plant trait measurement were made with a special set of orthogonal polynomial coefficients. Nodulation maximums were at greater planting depths (19 and 22 mm) than seedling number maximums (6 and 10 mm) in early and pooled irrigation blocks, respectively. Number of plants and nodules per plant were optimum at the balanced compromise depth of 13 mm and in a range of 10 to 30 mm for early irrigation. With pooled irrigation or simulated dryland planting the balanced compromise point was 16 mm and the range 10 to 25 mm for optimizing planting depths. Surface or 40 mm depths were hazards to establishment of the small‐seeded legume, and its rhizobium. Pelgel sticker significantly increased nodulation over water sticker and the untreated check with early irrigation at 0 and 10 mm planting depths, but in all irrigation treatments nodule numbers were increased by pelgel sticker only in plantings at 10 mm depth. Biomass and plant number were significantly correlated under both early and delayed irrigation treatments (0.95 and 0.98, respectively) due to poor growth environment.
Magnesium Uptake by Tomato Plants as Affected by Mg and Ca Concentration in Solution Culture and Plant Age1
Authors: Schwartz S. , Bar‐Yosef B.
Published: July 2010

Magnesium deficiency of tomato (Lycopersicon esculentum Mill.) plants grown under glass and in the field is widespread. Deficiency may occur because of interference in Mg uptake by various cations or from diminishing rates of uptake resulting from root aging. To investigate the interrelationship of Ca and Mg uptake by tomato plants and the dependence of uptake on plant age, a solution culture study with various Mg and Ca concentrations (CMg, CCa) was conducted. From solution depletion measurements of Ca and Mg during 2 to 3‐day periods, net cation flux (Fmax) and Michaelis‐Menten uptake rate coefficients were estimated for various plant ages (18 to 21, 34 to 37, and 80 to 83 days) and solution composition. Enhanced CCa (2.5 vs. 1 meq/L) decreased Fmax and KM of Mg. This effect was attributed to stimulation by Ca of selective ion uptake (related to KM) and a competitive effect on carrier sites which reduced Fmax. Increased CMg values had no appreciable effect on Fmax of Ca but they enhanced KM, especially during early growth (18 to 21 days). The flux of Mg uptake decreased with plant age. Between Days 21 and 83, Fmax, was reduced from 68 to 17.5 µeq Mg g fresh root−1day−1, while KM values under the same conditions increased from 0.55 to 1.2 meq/L. Similar changes with time characterized the Fmax and KM values for Ca. Root and canopy growth rates were appreciably retarded at CMg of 0.05 or CCa of 0.1 meq/L, relative to those at higher Mg and Ca concentrations. At the initial appearance of deficiency symptoms, Mg and Ca concentrations in the shoots were 0.13 and 0.11%, respectively.
Radiative Transfer in an Array of Canopies1
Authors: Norman J. M. , Welles J. M.
Published: July 2010

Theories describing radiative transfer in plant canopies are very well developed for canopies approximating full cover. However, for canopies of partial cover such as orchards, wide‐row crops or widely spaced individual plants, no general theory exists. This paper contains a description of a general radiative transfer model that is capable of accommodating nearly any canopy structure. The plant canopy is approximated by an array of ellipsoidal subcanopies that may be equally spaced, randomly spaced, or spaced in any manner desired. Ellipsoids were chosen because of the infinite variety of shapes that they can approximate. All of the foliage of any individual subcanopy is contained within the confines of its ellipsoidal subcanopy, and assumed to be statistically distributed within the subcanopy volume with respect to location, foliage angle, and foliage area per unit of subcanopy volume. The radiative transfer model includes attenuation of direct beam and sky diffuse radiation, multiple scattering for visible and near‐infrared wavelength, and emission for thermal wavelengths. When the subcanopies overlap extensively, the predictions from the general ellipsoidal model approach the predictions from one‐dimensional models applicable to canopies of full cover. Predictions from this three‐dimensional model are compared with cross‐row measurements in a corn canopy. In addition, sunfleck area and sunlit‐leaf area comparisons are made between this three dimensional model and a one dimensional model for a developing corn canopy.
Cotton Cultivar Response to Mepiquat Chloride1
Authors: York A. C.
Published: July 2010

The effects of mepiquat chloride (1,1‐dimethylpiperidinium chloride) on cotton (Gossypium hirsutum L.) growth and yield have been widely studied but few studies have investigated cultivar response to this plant growth regulator. Since the response to a pesticide or a plant growth regulator may vary among cultivars, a knowledge of cultivar response to that chemical is an important consideration when developing recommendations for its use. A 3‐year study was conducted in eight environments to determine if 14 cultivars respond differently to mepiquat chloride. Cultivars evaluated were ‘Coker 304’, ‘Coker 310’, ‘Coker 315’, ‘Coker 420’, ‘Deltapine 41’, ‘Deltapine 55’, ‘Deltapine 70’, ‘McNair 220’, ‘McNair 235’, ‘Rex 713’, ‘SC 1’, ‘Stoneville 213’, ‘Stoneville 506’, and ‘Stoneville 825’. Mepiquat chloride at a rate of 49 g/ha increased lint yield 10 to 28% in three environments and decreased yield 5% in one environment. Earlier maturity was usually observed. Plant height was reduced 11 to 26%, and reductions in plant height were closely correlated with final height of the untreated cotton. Mepiquat chloride increased both boll weight and seed weight 3 to 10%, and slightly increased fiber length. The effect on micronaire was variable, but in most environments there was a small reduction. There was little to no effect on number of seed per boll, fiber strength, and fiber length uniformity. Lint percent was decreased 0.4 to 0.8% in most environments as a result of the increased seed weight. There were no mepiquat chloride by cultivar interactions for lint percent, fiber length, boll weight, seed weight, number of seed per boll, number of bolls produced, plant height, or maturity. Cultivar by mepiquat chloride interactions for yield, micronaire, fiber strength, and fiber length uniformity were observed in only one environment. All observed mepiquat chloride by cultivar interactions were small and, considering the infrequency of occurrence, were probably not of practical significance. This study indicated that cultivar selection should not be a consideration in deciding whether to apply mepiquat chloride.
Corn Growth Response to Temperature and Photoperiod I. Seedling Emergence, Tassel Initiation, and Anthesis1
Authors: Warrington I. J. , Kanemasu E. T.
Published: July 2010

The efficient breeding and selection of corn (Zea mays L.) genotypes for different climatic regions requires a quantitative understanding of the plant's developmental responses to environmental factors such as temperature and photoperiod. This information is also essential if reliable and meaningful crop simulation models are to be developed. Plants of two corn hybrids, XL45 and W346 were grown in controlled environments under 18 day/night temperature combinations ranging from 16/6 to 38/33°C (12‐h photoperiod) and under three photoperiods (12,14, and 16 h) at two selected temperatures (constant 18 and 28°C). Data defining the temperature response curves, including the minimum and optimum temperature limits, for germination and emergence and for the development periods from sowing to tassel initiation and sowing to anthesis were obtained. A minimum temperature of 9°C was predicted for germination and emergence, and a requirement of 62.5 degree‐days was determined for this growth stage. The optimum temperature was approximately 30°C. Minimum temperatures of 8 and 7°C were determined for tassel initiation and anthesis, respectively, and the optimum temperature for both was 28°C above which the development rates declined. These temperature limits compared with minima and maxima of 10 and 30°C, respectively, used in most current heat‐sum methods. Between the limits of 7 and 28°C, the number of degree‐days required to reach tassel initiation and anthesis were, respectively, 208 and 736 for hybrid W346, and 245 and 816 for XL45. Tassel initiation occurred at approximately one‐third of the time between sowing and anthesis when calculated either on the basis of heat‐sums (degree‐days) or from calendar‐days under the steady‐state temperature conditions used. An increase in photoperiod lengthened both the time between sowing and tassel initiation and that between tassel initiation and anthesis in a similar, almost equal, manner for both cultivars. Sensitivity to the photoperiod response was not altered by temperature.
Design of a Large Dual – Structure Rainout Shelter1
Authors: Upchurch D. R. , Ritchie J. T. , Foale M. A.
Published: July 2010

In locations subject to rainfall during the cropping season, a rain excluding device must be employed to impose water stress for drought studies. A rainout shelter facility that covers 0.09 ha has been constructed for plant water stress research in central Texas. The shelter consists of twin structures connected to a single drive system and linking cable. The dual structures, which move together to cover the plot, incorporate permanent side and end walls thereby completely excluding driving rain. Minimum ground clearance of the wall allows some air movement under the closed shelter. Wind loading during shelter movement is neutralized as the structures move in opposite directions. The shelter is clad with fiberglass transmitting 70% of global radiation which allows continuing energy interception by the crop when the plots are covered. Movement of the building is controlled by a tipping bucket rain gauge, a local manual switch, and through telephone answering equipment connected electronically to the drive motor. The position of the building may be checked and changed by telephone. The sheltered area is large enough for replicated experiments with a satisfactory range of treatments. Several features have contributed to the successful operation of this shelter which is larger than any described previously.
Moisture Deficits and Grain Sorghum Performance: Drought Stress Conditioning1
Authors: Garrity Dennis P. , Sullivan Charles Y. , Watts Darrell G.
Published: July 2010

The exploitation of drought stress conditioning responses in field crops may enable substantial water savings in limited irrigation. We analyzed the effectiveness of stressing grain sorghum [Sorghum bicolor (L.) Moench] to varying degrees prior to the grain‐fill period in inducing a drought stress conditioning response during grain fill. A line source sprinkler system was used to apply two sets of treatments on the three sorghum hybrids in a field study conducted on a sandy soil (Typic Ustipsamment): Gradient irrigation (G) applied throughout all growth stages (GGG), or full irrigation (I) during the vegetative and reproductive periods, followed by gradient irrigation during the grain‐fill period (IIG). Large differences in total dry matter (DM) production and grain yields were observed due to different timings or magnitudes of water stress during grain fill (IIG) or throughout the growing season (GGG). However, the harvest index remained the same regardless of stress treatment. A substantial mobilization of stored assimilates from the stem to the grain was observed (up to 73% of grain weight) on the IIG treatment. The stress adjustment of hybrid RS 626 was significant enough to be of practical importance. Grain yields for the GGG and IIG were the same. Much greater seasonal soil water depletion occurred in the GGG than in the IIG treatment, while soil water extraction during grain fill was similar between the two treatments, although the IIG began this stage with a full profile. Dry matter and grain weight were much less sensitive to seasonal evapotranspiration (ET) deficits in the GGG treatment than in the IIG treatment, but seasonal water‐use efficiency in the GGG treatment was substantially higher. All hybrids had the same water‐use efficiency (WUE) in DM and grain production during the grain fill period. Hybrids, NB 505 and NC + 55X tended to escape the effects of grain fill stress by earlier maturity. Leaf area and canopy temperature comparisons suggest that they were not as physiologically sensitive to drought stress as hybrid RS 626 when stress was imposed with a prior conditioning stress. The results indicate that the magnitude of a drought stress conditioning response may be substantial, but will depend on the genotype used, the phenological timing of the treatment, and the irrigation regimen employed.
Laboratory and Field Evaluations of Sorghum for Response to Aluminum and Acid Soil1
Authors: Duncan R. R. , Clark R. B. , Furlani P. R.
Published: July 2010

Plant responses in controlled environments (greenhouse and growth chamber) should relate to field plant responses if laboratory screening methods are to be used effectively for the improvement of plant tolerances to soil stress conditions. Eight acid soil susceptible and tolerant sorghum [Sorghum bicolor (L.) Moench.] genotypes were compared for dry matter production, element uptake, and visual plant stress symptoms under field stress (Georgia) and artificially‐induced Al‐toxic nutrient solutions (Nebraska). Sorghum was grown on three soil types (Typic Rhodudults, Fragiaquic Paleudults, and Typic Hapludults) and at three levels of Al (0, 46, 93 µmol L−1) in nutrient solution. Net seminal root lengths were used to evaluate plants for Al tolerance in the laboratory. The objectives of this study were to compare sorghum genotype responses when plants were grown under both field and laboratory conditions to determine genotypic differences and to better quantify Al and acid soil tolerance screening techniques. Among the genotypes studied, SC0283 was the most tolerant to acid soil field stress conditions and was also the least affected by Al toxicity conditions in nutrient solutions. NB9040 was susceptible to acid soil field conditions, exhibited considerable tolerance to medium levels of solution Al, and was susceptible to high levels of solution Al. Tolerance or susceptibility to Al among the sorghum genotypes was influenced by the level of the acid soil stress condition. Manganese toxicity probably affected plant responses in the field. Genotype responses to Al‐induced stress conducted in the laboratory and to acid soil stress conducted in the field showed similar responses when the screening parameters for each environment were quantified. The susceptibility response of NB9040 was equivalent at 93 µmol L−1 Al (32 µmol L−1P) in solution and pH 4.4 to 4.8 for the three soils used in this study.
Effect of Sample Preparation and pH on the Cation Exchange Capacity of Thatch1
Authors: Danneberger T. K. , Turgeon A. J. , Peck T. R.
Published: July 2010

Where it develops excessively, the thatch layer may serve as the primary medium supporting the growth of a turfgrass community. Since little is known about the edaphic properties of thatch, the purpose of this study was to determine the effect of sample preparation and pH on the cation exchange capacity (CEC) of thatch. Samples were obtained from a Kentucky bluegrass (Poa pratensisL. cv. Merion) lawn using a cork borer with an inside diameter of 15 mm. The CEC was measured using both undisturbed samples and ground samples passing through a 40‐mesh screen. The effect of pH was determined at pHs of 2.5,3.5,5.0,6.0,7.0, and 8.0; results were analyzed by linear regression. No significant differences were observed due to grinding of the thatch samples; however, variation in CEC occurred depending upon the saturation solution used. The CEC expressed on an undisturbed volume basis was considerably lower than that based upon sample weight. A threefold increase in CEC occurred over a pH range of from 2.5 to 8.0.
Rapid Method For Measuring Kernel Density1
Authors: Wessel‐Beaver L. , Beck R. H. , Lambert R. J.
Published: July 2010

A rapid, accurate, and reproducible method for measuring corn kernel density is needed if selection for density in a breeding program is to be effective. Comparisons of two methods involving the Archimedes principle for measuring corn (Zea maysL.) kernel density included: 1) water displacement in a graduate cylinder and 2) a cage of kernels submerged in a tared water container resting upon a balance. Sixty samples of opaque‐2 corn (45 kernels each with densities from 960 to 1250 kg m‐3) were analyzed. The cage method required 67 vs. 136 min/60 samples for kernel volume measurements and was more repeatable (r = 0.94** vs. r = 0.67**). The coefficients of variation for the two methods and the two analysts ranged from 4.9 to 5.6%. The cage method is rapid, accurate and reproducible.
Persistence and Recovery of Rhizobium japonicum Inoculum in a Field Soil1
Authors: Ellis W. R. , Ham G. E. , Schmidt E. L.
Published: July 2010

Inoculation of soybean (Glycine max L.) rarely increases seed yields in fields where this crop has been previously grown. The inability of the inoculum strain to persist in soil could be a factor in this poor response. The persistence of the inoculant strain Rhizobium japonicum USDA 110 was followed for 56 weeks in a field soil (Typic Haplaquoll) using a fluorescent antibody technique. Statistically significant increases in the population of R. japonicum strain USDA 110 in soil were observed for the first 7 weeks after inoculation. When USDA 110 was applied at 2 × 106 cells g−1 soil the population of this organism in soil reached 1 × 107 cells g−1 soil 1 week after inoculation; a value significantly higher than observed in other inoculation and fertilization treatments. The population observed for the uninoculated control varied nonsignificantly from 6 × 104 to 2.6 × 105 cells g−1 during both growing seasons. No significant differences due to inoculation were observed for seed yield, or total aboveground N in either year. Even though the soil population was increased significantly, inoculation of strain USDA 110 at high rates produced no significant alteration in strain distribution in the nodules of soybeans in either year. Rhizobium japonicum strain USDA 110 was observed mostly in doubly infected nodules with strain USDA 123 which may have minimized the effect of strain USDA 110 on N2 fixation and seed yield.
Assessment of Visual Evaluation Techniques1
Authors: Horst G. L. , Engelke M. C. , Meyers W.
Published: July 2010

Visual evaluation parameters are routinely used to assess performance characteristics of turfgrass cultivars in field plantings. Rating systems are commonly employed to evaluate phenotypic variations in color, density, and uniformity of turfgrass stands during the year. In the present study, visual assessment data for quality and density ratings of cultivars of Kentucky bluegrass (Poa pratensis L.) and tall fescue (Festuca arundinacea Schreb.) from 10 turfgrass researchers were statistically analyzed to determine data conformity, consistency, and uniformity. Analysis of simultaneous data gathering by 10 investigators indicated the following: 1) Visual assessment scales were significantly different among evaluators, 2) Visual criteria used for data collection allowed a wide latitude of perception in quality and density characteristics, 3) Relative rank performance of cultivars differed among evaluators, and 4) Presently accepted techniques for visually assessing turfgrass quality and density are inadequate. Results of national and regional turfgrass cultivar evaluation trials should be considered with caution as most performance variables are based on the use of conventional evaluation schemes. This study emphasizes the need for a coordinated development of qualitative evaluation techniques based on substantiated, biologically definable, growth responses rather than visual perception.
Interactive Effects of Salinity and Substrate Phosphate on Soybean1
Authors: Grattan S. R. , Maas E. V.
Published: July 2010

Preliminary experiments at this laboratory indicated that salt injury of soybeans [Glycine max (L.) Merr.) is strongly dependent upon the inorganic phosphate (Pi) concentration in the substrate. Inorganic phosphate concentrations that are commonly used in nonsaline solution cultures were lethal to ‘Kanrich’ and ‘Prize’ cvs. in saline media. A solution culture experiment was conducted in the greenhouse to examine the interactive effects of salinity (−0.04, −0.24, and −0.44 MPa osmotic potential) and substrate Pi (0.02,0.10,0.20, and 0.30 mmol L−1) on shoot and root growth, foliar injury, and tissue element concentration on five soybean cvs. [‘Clark’ (P‐sensitive), ‘Jackson’ (salt‐sensitive, P‐tolerant), ‘Lee’ (salt‐tolerant, P‐tolerant), ‘L63‐1677’ (P‐tolerant), and Kanrich]. Increased Pi had no effect on growth under nonsaline conditions but in the presence of salinity it significantly reduced shoot and root growth of Clark and Kanrich cvs. only. High salinity (−0.44 MPa) in combination with Pi ≥ 0.10 mmol L−1 killed both Clark and Kanrich cvs. However, at 0.02 mmol L−1 Pi and high salinity, no foliar injury was found on Kanrich and only slight chlorosis was found on Clark. In contrast, no foliar injury was apparent on Lee in any treatment. Inorganic phosphate increased the severity of injury in L63‐1677. Salinity greatly enhanced Pi accumulation in leaves and roots of Clark and Kanrich; whereas this effect was slight for the P‐tolerant cvs. Lee, Jackson, and L63‐1677. Injured Clark and Kanrich leaves contained abnormal amounts of P (400 to 800 mmol kg−1, dry wt) indicating that the primary cause of injury was a salinity‐induced Pi toxicity. Salinity also induced considerable foliar injury on Jackson; yet the onset and severity was independent of the substrate Pi concentration. Unlike the mechanism of foliar injury in Clark and Kanrich, we suspect injury in Jackson was caused by Cl toxicity. The striking adverse interaction between salinity and phosphate is a critical factor in solution culture studies of plant tolerance to salinity. These results further demonstrate that important genetic differences exist among cultivars that greatly affect their susceptibility to Pi toxicity.
Abscission, Total Soluble Sugars, and Starch Profiles within a Soybean Canopy1
Authors: Antos Matthew , Wiebold W. J.
Published: July 2010

Reproductive abscission is greatest in the lower one‐third of soybean (Glycine maxL. Merr.) canopies. It has been hypothesized that low carbohydrate availability is responsible for abscission of soybean flowers and pods, The cv. Williams was used to determine canopy distribution of flower and pod number, reproductive abscission, and the concentration of total soluble sugars (TSS) and starch in soybean leaflet, petiole, stem, and reproductive tissues. The plants were field grown (Beltsville silt loam; a fine‐loamy, mixed, mesic Typic Fragiudult) and harvested four times during reproductive development (R1.5, R3.0, R5, R6). Two treatments, no shade and 75% shade, were used. Shades were in place 11 days for each physiological stage. Flower number, pod number, and reproductive abscission percentages were determined during these 11 day periods for both treatments. All characters were determined for three strata within the canopy. Total abscission throughout the growing season was 68 and 61% in 1978 and 1979. Abscission within the upper, middle, and lower strata, averaged over 2 years, was 38, 59, and 98%, respectively. Partial shade increased percent abscission at R3 and R6 of 1978 and not at all in 1979. In 1978, TSS concentration within leaflets, petioles, and stems reached a maximum value at R5, R3, and R6, respectively. In 1979, TSS of petioles and stems increased throughout reproductive development, but TSS of leaflets fluctuated between stages. Stage of development had an effect only on the starch concentration of petioles. In this instance maximum starch concentration occurred at R5. Significant canopy strata effects on TSS and starch concentration of stems and petioles were found at most stages of development. In these instances, concentrations of the lower one‐third canopy were smaller than concentrations of the middle and/or upper canopy region. Large abscission percentages were associated with small concentrations of stored carbohydrates.
Salinity Effects on Seed Yield, Growth, and Germination of Grain Sorghum1
Authors: Francois L. E. , Donovan T. , Maas E.V.
Published: July 2010

Grain sorghum (Sorghum bicolor(L.) Moench] is grown on saline soils in the western United States. Because of the lack of information on salinity effects on seed yield, a field plot study was conducted. Six saline treatments were imposed on a Holtville silty clay (clayey over loamy montmorillonitic (calcareous), hyperthermic Typic Tor‐rifluvents) by irrigating with waters that were salinized with NaCl and CaCl2(1:1 by wt). The electrical conductivities of the irrigation waters were 1.5, 2.7, 5.0, 7.4, 9.8, and 12.1 dS/m. Germination, vegetative growth, and grain yield were measured. Relative grain yield of two cultivars, Double TX and NK‐265, was unaffected up to a soil salinity of 6.8 dS/m (electrical conductivity of the saturation extract: Κe). Each unit increase in salinity above 6.8 dS/m reduced yield by 16%. This indicated that grain sorghum is moderately tolerant to salinity. Yield reduction was due primarily to lower weight per head rather than a reduced number of heads. Vegetative growth was affected less by increasing soil salinity than was grain yield. Grain sorghum was significantly more salt tolerant at germination than at later stages of growth.
Moisture Sensor‐Controlled Irrigation for Maintaining Bermudagrass Turf1
Authors: Augustin B. J. , Snyder G. H.
Published: July 2010

The feasibility of tensiometer soil moisture sensing devices for scheduling bermudagrass (Cynodon dactylon× C. transvaalensis) turf irrigation and their impact on N fertilization practices under sub‐tropical conditions was assessed. Irrigation water savings of 42 to 95% were obtained in sensor controlled plots over conventionally irrigated plots. The greatest benefit of the sensor system was achieved during periods of frequent but unpredictable rainfall by eliminating unnecessary irrigations. Application of a wetting agent was necessary during extended dry periods to prevent localized dry spots when irrigation was limited by the sensor system to an as needed basis. Reduced irrigation by the sensor system resulted in better turf appearance and equal effectiveness of water‐soluble and slow‐release N sources.
Salt Tolerance of Grasses and Legumes for Roadside Use1
Authors: Greub L. J. , Drolsom P. N. , Rohweder D. A.
Published: July 2010

Salt injury to grasses and legumes in roadside seedings is becoming an increasingly serious problem in areas where deicing salt is used during winter months. This paper reports on results of three greenhouse trials conducted to evaluate salt tolerance among 40 grass and legume species, cultivars, and genotypes. A 2.65 M sodium chloride (NaCl) solution was added weekly for up to 5 weeks to pots of seedling plants in a Derinda silty clay loam (fine, mixed, mesic Typic Hapludalfs). Salt tolerance was measured by comparing dry matter (DM) yields of salt and no‐salt treatments and by visually scoring foliage injury. In the final trial, which involved a rescreening of the most salt tolerant species from all previous trials, 14 of the 15 entries had salt treatment DM yields which were not significantly different from no‐salt treatment yields, and five also had salt treatment foliage injury scores which were not significantly different from those of the no‐salt treatment. These five were: lemmon alkaligrass [Puccinellia lemmoni (Vasey) Scribn.]; alkali sacaton [Sporobolus airoides (Torr.) Torr.]; nuttall alkaligrass [Puccinellia airoides (Nutt.) Wats. and Coult.]; a Puccinellia roadside selection, and weeping alkaligrass [Puccinellia distans (L.) Parl.]. Entries which had no significant DM yield reduction but showed serious foliage injury were: creeping bentgrass [Agrostis stolonifera L., var. palustris (Huds.) Farw.] cv. Seaside; quackgrass [Agropyron repens (L.) Beauv.]; tall fescue (Festuca arundinacea Schreb.) cv. Alta; perennial ryegrass (Lolium perenne L.) common and cv. NK 200, creeping meadow foxtail (Alopecurus arundinaceus Poir.) cv. Garrison; redtop (Agrostis alba L.); creeping red fescue (Festuca rubra) cv. Ruby; and rough stalk bluegrass (Poa trivialis L.). Among legumes tested, alfalfa (Medicago sativa L.) cv. Vernal and sainfoin (Onobrychis viciaefolia Scop.) cv. Eski were the most salt tolerant, but both ranked lower than the better grasses. Six Kentucky bluegrass (Poa pratensis L.) cultivars were among those entries which had the greatest dry matter yield reductions and the most severe foliage injury when treated with salt.
Heritability of NaCl Tolerance in Germinating Alfalfa Seeds1
Authors: Allen S. G. , Dobrenz A. K. , Schonhorst M. H. , Stoner J. E.
Published: July 2010

A major limitation to crop production throughout much of the world is soil salinity, which is increased by irrigation and fertilization. One way to better utilize saline soils is to grow salt tolerant crops. The objective of this research was the development of salt tolerance in germinating alfalfa (Medicago sativa L.) seeds. Five cycles of mass selection for NaCl tolerance during seed germination were conducted in the cv. Mesa‐Sirsa. Standard germination techniques were employed using blotter paper saturated with NaCl solutions of five different concentrations at a temperature of 26° C. The osmotic potential of the NaCl solution needed to produce 1% seed germination decreased from −1.40 to −2.45 MPa during the five cycles of selection. Germination at −1.30 MPa osmotic potential increased from 3% for the source population to 86% for the fifth cycle of selection. The broad sense heritability estimate for NaCl tolerance during seed germination, averaged over all cycles of selection and five levels of osmotic potential, was 50%. Significant progress was made in the development of salt tolerance in germinating alfalfa.
Germination of Basin Wildrye and Tall Wheatgrass in Relation to Osmotic and Matric Potential1
Authors: Roundy Bruce A. , Young James A. , Evans Raymond A.
Published: July 2010

Tall wheatgrass [Agropyron elongatum (Host) Beauv. ‘Jose’] and basin wildrye (Elymus cinereus Scribn. and Merr. ‘Magnar’) may have great potential for increasing the forage production of saline and arid rangelands. To determine the potential of these species to germinate and emerge in saline, arid seedbeds germination responses were studied in the laboratory in relation to decreasing medium osmotic and matric potentials, seed water contents, and seed water potentials. Tall wheatgrass had higher total germination, a higher germination rate and greater radicle growth than basin wildrye in solutions of polyethylene glycol 6000 (PEG), NaCl, Na2SO4, and CaCl2. Ion toxicity was evidenced by lower germination rates and radicle growth of both species in the salts than in PEG. Tall wheatgrass seeds were more tolerant of Na and chloride than of Ca or sulfate ions. Tall wheatgrass required less incubation days to emerge and emerged at lower soil matric potentials than basin wildrye. Both species had lower emergence in soil at reduced matric potentials than in PEG and salt solutions of equivalent osmotic potentials where seed‐soil contact and hydraulic conductivity were not limiting factors. Tall wheatgrass germinated at lower seed water contents and seed water potentials than basin wildrye. Although Jose tall wheatgrass is more likely to germinate and emerge in saline, arid seedbeds than Magnar basin wildrye, Magnar has higher germination and germinates at lower osmotic potentials than other collections of basin wildrye previously tested.
Response of Selected Soybean Cultivars to Soil Moisture Deficit1
Authors: Brown E. A. , Caviness C. E. , Brown D. A.
Published: July 2010

Extensive research has been conducted on effects of moisture stress on growth and development of soybean [Glycine max (L.) Merr.] but information is limited on the response of determinate cultivars to moisture stress initiated at different growth stages. Moisture is a major factor limiting yield in most areas where soybeans are grown. Moisture stress experiments were conducted under field conditions using four determinate soybean cultivars of Group VI maturity, ‘Davis’, ‘Lee 74’, ‘Sohoma’, and ‘Centennial’. The experiments were conducted in 1980 and 1981 on a Captina silt loam (fine‐silty mixed, mesic Typic Fragiudult) at Fayetteville, AR. These experiments consisted of two moisture stress treatments which were initiated at the R2 and R4 growth stages and a control which was irrigated as needed throughout the season. Measurements were made on both roots and aboveground plant parts. When a moisture deficit was initiated by placing black plastic over the plots at either R2 or R4, seed yield was significantly reduced both years. A moisture deficit following application of plastic at R2 reduced yield more than at R4 in 1981, but the reverse was found in 1980, an extremely dry year. A moisture deficit initiated at R4 significantly reduced seed size and seed number both years whereas seed size was not significantly reduced either year by deficits initiated at R2. Sohoma produced significantly larger seeds than the other three cultivars when plants were moisture stressed at R4. No significant cultivar X moisture stress interactions involving seed yield were observed in either year; however, there was a definite trend for seed yields of Sohoma to be reduced less by moisture deficits initiated at stage R4 in both 1980 and 1981. Percent flower and pod shedding did not appear to be affected to any great extent by the moisture stress treatments in either year. In general, as the total number of flowers and pods increased, the number of flowers and pods shed increased proportionally. There were about four times as many roots under the row as were present in the furrow middles in both years. Also, a moisture deficit restricted root growth under the row in the upper portion of the profile, but increased it in the lower portion in the dry year of 1980.
Annual Bluegrass Growth and Quality as Influenced by Treatments of Growth Retardants and Wetting Agents1
Authors: Petrovic A. M. , White R. A. , Kligerman M.
Published: July 2010

It is difficult to maintain the visual quality of annual bluegrass (Poa annuaL.) during the summer because of its poor heat and drought tolerance, which could be related to the reduction of the root system and/or depletion of the carbohydrate reserves that occur during the intensive spring flowering period. Therefore, the objective of this study was to determine the effects of treatments of plant growth retardants and wetting agents on the growth and visual quality of annual bluegrass. The growth regulators mefluidide [N(2,4‐dimethyl‐5{[ (trifluoromethyl)sulfonyl]amino}phenyl) acetamide] and amidochlor {N‐[(acetylamino)methyl]2‐chloro‐N‐(2,6‐diethylphenyl) acetamide} and the wetting agents Aqua Gro (Aquatrols Corp. of America, Pennsaukin, NJ), Hydro Wet (Kalo Labs., Inc., Kansas City, MO), Basic H (Shakley Marketing Corp., Emeryville, CA), and Amway Spray Adjuvant (Amway Corp., Ada, MI) were applied prior to or at the initiation of the flowering period to annual bluegrass fairways (Dunkirk fine silt loam, fine silty, mixed mesic, Glossoboric Hapladalfs) over a 3‐yr period. Seedhead production and seed yield were reduced significantly by mefluidide, Aqua Gro, and amidochlor. The reduction ranged from 64 to 99%, 26 to 77%, and 40% for mefluidide, Aqua Gro, and amidochlor, respectively, depending on rate and timing of application and year of the study. The other wetting agents had no affect on seedhead production. Mefluidide reduced clipping yields 20% over a 2‐month period, whereas Aqua Gro had no effed. In 2 of the 3 yr of the study, mefluidide applications caused a reduction in the visual quality of annual bluegrass 14 to 24 days after treatment. Aqua Gro effects on the visual quality during the spring flowering period were inconsistent. The visual quality of annual bluegrass during the summer months, however, was not affected by the degree of spring seedhead production.
Crop Responses to Phosphorus and Potassium Fertilization of a Sodic Soil1
Authors: Chhabra R.
Published: July 2010

Uncultivated sodic soils in the Indo‐Gangetic alluvial plains of India contain high amounts of NaHCO3‐extractable P. However, the P fertilizer needs of crops grown on such soils is unknown. A longterm field experiment was conducted on a representative sodic soil (Aquic Natrustalf) with the following objectives: (i) evaluating rice (Oryza sativaL.) and wheat (Triticum aestivumL.) responses to P and K fertilization, and (ii) monitoring changes in soil‐extractable P and exchangeable K as affected by the addition of gypsum, fertilizers, and cropping. The treatments included annual application of 0 and 22 kg ha−1P as single superphosphate and 0 and 42 kg ha−1K as muriate of potash, to either wheat or to both rice and wheat grown in a rotation. In any individual year, the yields of rice and wheat were not affected by application of P and K. However, over a period of 6 yr, the mean yield of rice in control plots was lower than yields in fertilized plots. The P concentration in grain was less affected by fertilization than that of the straw. The K concentration of grain and straw of either crop was not affected. After reclamation, NaHCO3‐extractable soil P for all treatments, decreased in the first year, from 46 kg ha−1to a mean value of 22 kg ha−1. Application of 22 kg P ha−1to both crops increased the extractable soil P to 27.6 kg ha−1. In the control plot, the extractable soil P decreased each year and was reduced to 7.2 kg ha−1after 6 yr. Exchangeable K in the soil decreased in control and P fertilized plots, but the values were much above the critical limit. Apparently, in recently reclaimed sodic soils, rice and wheat may be grown without P and K fertilization for the initial 6 yr without reduction in yield.
Planting Date Effects on Seedling Development of Perennial Warm‐Season Forage Grasses. II. Seedling Growth1
Authors: Hsu F. H. , Nelson C. J.
Published: July 2010

Perennial warm‐season forage grasses can improve animal performance in summer when cool‐season grasses become dormant and low in forage quality. Rapid establishment of acceptable stands is a factor limiting their use. Field experiments were conducted to determine optimum planting dates of perennial warm‐season forage grasses, determine effects of planting date on seedling growth and partitioning of dry matter between roots and shoots, and compare strategies of seedling growth among perennial warm‐season grasses and an annual weed. Seeds of big bluestem (BB) (Andropogon gerardiiVitman), Caucasian bluestem (CB) [Bothriochloa caucasica(Trin.) C. E. Hubb.], indiangrass (IG) [Sorghastrum nutans(L.) Nash], switchgrass (SG) (Panicum virgatumL.), and an annual species, crabgrass (CG) [Digitaria sanguinalis(L.) Scop.] were planted at approximately 2‐week intervals from early April to late June in 1982 and 1983. A split‐plot design was used with five replications. Soil was a Mexico silt loam (fine, montmorillonitic, mesic Udollic Ochraqualf). Weeds were removed by hand shortly after their emergence in 1982, while weed emergence was prevented by methyl bromide (bromomethane) treatment in 1983. All species within a given planting data were harvested when BB reached the fifth collared‐leaf stage. Crabgrass developed more leaves, had greater leaf area, and accumulated more dry matter than did perennials showing that it would exhibit strong competition to perennials during establishment. Among perennials, SG and IG developed more leaf area and accumulated more dry matter than did CB and BB. However, CB developed more leaves and tillers than did other perennials, but leaves were small. Both SG and CB had higher leaf area ratios and lower root/shoot ratios than did IG and BB. Big bluestem required fewer days to reach the fifth collared‐leaf stage on later plantings than on early plantings, but in 1982 total dry matter accumulation at the fifth leaf stage was similar among planting dates. In 1983, however, dry matter accumulation and leaf area of BB were highest when seeds were planted on 6 and 16 May. In both years the root/shoot ratio of BB was highest for early plantings and decreased as planting was delayed. Other species showed similar trends. Dry matter production averaged over planting dates for CB, IG, and SG, respectively, was 1.2, 2.5, and 2.1 times greater than BB in 1982, and 1.6, 2.6, and 3.4 times greater than BB in 1983. Perennial warm‐season forage grasses are adapted for planting between late April and mid‐May, a period when low temperatures occur to partially chill seeds and adequate soil moisture is available to allow development of the permanent root system prior to drought conditions.
Soil Water Balance of Intercropped Maize and Cowpea Grown in a Tropical Hydromorphic Soil in Western Nigeria1
Authors: Hulugalle N. R. , Lal R.
Published: July 2010

Water‐use efficiency (WUE) and soil water extraction by four maize (Zea maysL.)/cowpea (Vigna unguiculataWalp.) cropping patterns were studied in a tropical hydromorphic soil over two consecutive growing seasons in 1983 and 1984. The cropping patterns used were: monocropped cowpea (T1), monocropped maize (T2), intercropped maize and cowpea planted in the same row as alternate plants (T3), and intercropped maize and cowpea planted in alternate rows (T4). Evapotranspiration (Et) was calculated from the soil water balance. Soil water extraction was limited to the surface 0.35 m of the profile due to the restriction of roots by a gravel layer at this depth. Upward water flux into the root zone was negligible due to low hydraulic conductivity. All cropping patterns were subjected to drought stress in 1983. Mean runoff and net water flux in the root zone in 1983 and 1984 were 2.4 and 0.04%, respectively, and 1.4 and 0.4%, respectively, of the seasonal rainfall. Intercropping increased seasonal WUE. The WUE (kg grain per mm water per ha) of T1, T2, T3, and T4were 0.5, 2.2, 1.6, and 1.6, respectively, for the droughty conditions in 1983 and were 2.1, 2.1, 4.2, and 3.6, respectively, for the favorable moisture regime in 1984. One of the benefits of intercropping maize and cowpea is, therefore, a higher WUE in relation to monocropping provided soil water is not limiting