bluuebunny/crossref_metadata_2025_split huggingface dataset:
Responses of Corn Earworm Larvae to Maize Silks1
Authors: Widstrom N. W. , Wiseman B. R. , McMillian B. R. 
Published: July 2010

AbstractLaboratory identification of maize (Zea mays L.) lines which have detrimental silk factors to the corn earworm [Heliothis zea (Boddie)] usually require several silk feedings over a period of 10 to 20 days. Seven maize lines were evaluated in a diallel crossing system for the number of larvae recovered from infested ears after 3 days, to determine the level of genetic variability for antibiosis, and to investigate the feasibility of using 3‐day laboratory measurements to identify genotypes that show antibiosis in the field. Five of these lines were reported as having detrimental silk factors or antibiosis to the corn earworm and two were used as susceptible checks. Genetic differences existed among lines and crosses, but heritability estimates were less than 25%. Measurements of larval antibiosis expression on excised silks in the laboratory were neither consistent nor indicative of the field ratings for larvae recovered. Only Od3 and ZC 2451, of the seven lines tested, had a measurably better level of antibiosis expression than the checks when tested as an inbred. 81‐1 was best in single‐cross combinations. The data suggest that ears of inbreds generally provide a more hostile environment to corn earworm larvae than ears of single crosses. We conclude that the technique of measuring 3‐day larval antibiosis expression does not provide sufficient time for larval antibiosis symptom manifestation and that an effective selection program of maize population improvement will require a longer ear‐larvae association time.
Responses of Greenhouse‐grown Cannabis sativa L. to Nitrogen, Phosphorus, and Potassium1
Authors: Coffman C. B. , Gentner W. A. 
Published: July 2010

AbstractGrowers of illegal Cannabis sativa L. use various cultural practices to maximize crop production. The objective of this study was to evaluate the morphological and biochemical responses of greenhouse grown C. sativa to soil incorporated N, P, and K as they reflect the geographical origin of Cannabis derivatives. Fertilizers were blended with Ap horizon soil from a Gilpin silt loam before placement in 12‐cm pots. NH4NO3‐N was applied at 0, 25, and 125 ppm. Phosphorus and K from super‐phosphate and KCI, respectively, were applied at 0, 50, and 150 ppm. Forty‐five‐day‐old anthesic Cannabis plants were harvested and combined leaf and flower tissues were analyzed for cannabidiol (CBD) and Δ9‐tetrahydrocanna‐binol (Δ9THC). Nine essential elements were also measured in plant tissue. Plant growth, tissue yield, and concentration of CBD and Δ9THC were positively correlated with extractable P2O5 (p < 0.01). Phosphorus concentrations in tissue were similarly related to yield of dry matter and cannabinoid concentrations. Uptake of K was positively correlated with extractable K2O across all treatment levels (r=0.40**), but was negatively correlated with tissue yield (r=‐‐0.36**). Growth and tissue yields were negatively related to total plant N (p< 0.01). Levels of extractable P2O5, Mn, B, and Mg were associated with specific concentration ranges for several plant elements plus Δ9THC. Thus, it was possible to partially characterize a soil by tissue analysis. For example, all of the plants grown on soil with less than 100 ppm of extractable P2O5 contained less than 8,000 ppm Δ9THC. Usefulness of such relationships will be dependent upon extensive evaluation of Cannabis on different soils under various cultural conditions. At this time, the reliability required for determination of origin of Canabis derivatives via chemical analysis does not exist when only essential elements and cannabinoids are considered.
Canopy Characteristics of Narrow‐Row Cotton as Influenced by Plant Density1
Authors: Buxton D. R. , Briggs R. E. , Patterson L. L. , Watkins S. D. 
Published: July 2010

AbstractThe optimum plant density for narrow‐row cotton (Gossypium hirsutum L.) is influenced by the lint yield response to plant density as well as other crop characteristics affecting crop management. This study was conducted to quantify the effect of population density on many of these characteristics. Three experiments were conducted with narrow‐row cotton in population densities ranging from 7.1 to 22.9 plants/m2. In August plants were harvested at ground level and morphological measurements were made. At the end of the growing season lint yield was determined. There were no statistical effects of plant density on lint yield or boll and fiber properties. Population pressure increased plant height when plants were young, while the effect on older plants was inconsistent. The morphological measurements showed (a) each five plants/m2 increase in, plant population decreased the number of mainstem nodes by one, (b) each eight plants/m2 increase in population decreased the number of monopodial branches per plant by one, (c) each 11 plants/m2 increase in population density raised the lowest sympodial branch with a boll by one node. In addition increasing density from about seven to 30 plants/m2 reduced the percentage of bolls supported by monopodial branches in a curvilinear manner from 25 to 0. Increasing plant density, also increased leaf area density, especially in the central portion of the plant canopy. Considered with their probable influence on harvesting efficiency, incidence of diseases and insects, and chemical defoliation, these data should help in predicting the optimum population for narrow‐row cotton. For these studies the optimum appears to be between 10 and 15 plants/m2.
Response of Leaf Water Potential to Pressure Changes at the Root Surface of Corn Plants1
Authors: Nulsen R. A. , Thurtell G. W. , Stevenson K. R. 
Published: July 2010

AbstractThe nature of the hydraulic continuum between the roots and leaves of intact plants requires further study to improve our understanding of the effect of pressure changes. A large pressure chamber was designed to apply hydrostatic pressure to the roots of intact corn (Zea mays L.) plants. The chamber permitted application of up to 6 bars pressure and allowed for in situ watering of the plants. Changes in leaf water potential resulting from changes in pressure applied to the roots were monitored in situ using a thermocouple dewpoint hygrometer. Responses of leaf water potential were consistently between 0.94 and 1.19 times the change in applied pressure, regardless of whether the pressure was being increased or decreased. When pressure was applied to very turgid plants leaf water potential increased until it reached a value equal to the osmotic pressure of expressed xylem sap. Some time after this value was reached water droplets appeared on the leaf surface. The experiments showed that the hydraulic system within intact plants acts as a true continuum in that pressure changes at one end of the system are faithfully, manifested at the other end of the system. If such changes are not observed some additional mechanism must be operating.
Modeling Daily Dry Matter Production of Winter Wheat1
Authors: Hodges Tom , Kanemasu E. T. 
Published: July 2010

AbstractApplicability of many plant growth models are limited because of the input data requirements. Photosynthesis and respiration equations were developed from meteorological data that could easily be obtained. The single crop parameter required was leaf area index. These equations were developed for winter wheat from measurement of net CO2 exchange with field chambers and an infrared‐gas‐analysis system. Higher gross photosynthesis rates after jointing were attributed to sink enhancement of photosynthesis. Respiration was estimated as a photosynthesis‐dependent growth component and a temperature‐biomass dependent maintenance component. The equations predicted dry matter production that agreed favorably with observed dry matter accumulation.
Grazing Pressures and Animal Performance from Pearl Millet1
Authors: McCartor M. M. , Rouquette F. M. 
Published: July 2010

AbstractIn the Gulf Costal Plain adapted summer annual forages such as pearl millet [Pennisetum typhoides (Burm.) Stapf and C. E. Hubb] are generally higher in energy content than perennial grasses and are capable of producing higher rates of gain. However, practically no data are available which define animal performance at different levels of forage utilization. The lack of definitive data on which to base a grazing program with pearl millet prompted this study which determined liveweight gains of weanling cattle grazing ]pearl millet and evaluated the relationships between gain, forage yield, forage quality, grazing pressure, and profitability.A hybrid pearl millet ‘Millex 23’ was seeded at the rate of 15 kg/ha on Thenas (Fluvaquentic Eutrochrept; coarse, loamy, mixed, thermic) soil and fertilized with 112 kg/ha each of N, P2O5, and K2O in each of 2 years. Weanling crossbred beef calves were used as tester animals and grazed at stocking rates ranging from 3.73 to 11.35 animals/ha. Liveweight average daily gains (ADG) from 0.27 to 1.01 kg were shown to be a non‐linear function of forage availability and a positive linear function of percent in vitro dry matter disappearance (IVDMD) available forage. Percent IVDMD of available forage varied from 36.29 to 63.57% and was inversely related to length of trial. Neutral detergent fiber values for available forage were negatively correlated with ADG (r= −0.84).Maximum profitability, expressed as return per ha, was found at intermediate grazing pressure and was dependent upon the magnitude of positive or negative margin between the time of purchase and the time of selling. Maximum profit occurred at greater grazing pressures as the positive margin between selling and purchase price increased.The most important factor affecting the profitability of grazing pearl millet was the differential between buying and selling price of the cattle. Aside from this factor, which the farmer seldom controls, grazing pressure is the most important determinant of profit. It was concluded that the greatest profit or least loss occurs at medium grazing pressures which, in this study, was approximately 2 kg of available forage per kg of animal liveweight.
Effects of Phosphorus and Potassium on Soybean Nodules and Seed Yield1
Authors: Jones G. D. , Lutz J. A. , Smith T. J. 
Published: July 2010

AbstractMuch of the nutritional research on soybean [Glycine max (L.) Merrill] nodulation has been under greenhouse or laboratory conditions. Additional field data are needed on the influence of nutrients on nodulation and other plant characteristics. The purpose of this investigation was to determine under field conditions the effects of P and K fertilization on number and weight of soybean nodules; the chemical composition of leaves, nodules, and seed; the number of pods per plant; and seed yield.Annual P rates of 0, 15, 30, and 60 kg/ha were applied with 0 and 112 kg K/ha in one field experiment. In another, annual K rates of 0, 28, 56, and 112 kg/ha were applied with 0 and 60 kg P/ha.Either P or K applied alone increased the number of nodules per plant and per unit volume of soil. Applied K increased the number of nodules, total and individual weight of nodules, and the number of pods per plant more than P, but increases were largest when both P and K were applied.Applied K increased the K concentration of nodules, but had little influence on N, P, Ca, Cu, Fe, Mn, and Zn concentration, and decreased Mg; applied P without K increased the P concentration. There was a good correlation between the relative concentrations of P and K in leaves sampled for each of four different sampling dates and the concentration of these elements in the seed. Applied P in excess of 15 kg/ha did not increase soybean yields. Each additional increment of K up to the maximum used (112 kg/ha) resulted in seed yield increases when P was also applied, but with no added P seed yield responses to more than 28 kg K/ha were not significant.These results showed that application of both P and K individually increased nodulation and pod formation with more response from K than P. Maximum response was obtained when both elements were added. Even though the soil was very low in available P when the experiment was initiated there was no seed yield response to more than 15 kg P/ha. A good yield response was obtained from 28 kg K/ha and to increasing rates of K when 60 kg P/ha was added, thus indicating the higher requirement of soybeans for K than for P.
Clover N‐Fixation Measurement by Total‐N Difference and 15N A‐Values in Lysimeters1
Authors: Williams W. A. , Jones M. B. , Delwiche C. C. 
Published: July 2010

AbstractAssessment and improvement of N fixation by legumes on annual‐type range is becoming increasingly important in light of the increasing need for energy conservation. A comparison was made of two methods of assessing N fixation: a simple but crude method by measuring the total‐N difference in tops of an N‐fixing legume and a non N‐fixing grass, and a more expensive method using A‐values determined from 15N applications to the same legume and grass species. Subterranean clover (Trifolium subterraneum L.) and soft chess grass (Bromus molis L.) were grown in field lysimeters (69 cm deep by 36 cm diam.) filled with Josephine loam (Typic Haplozerults, fine loamy, mixed mesic) for 3 years. Single (100 and 500 kg/ha) and repeated (100 kg/ha) applications of 15N were made and determinations were made of soil and fertilizer N in the plants, soil, and leachate periodically. The relation between the two methods was strongly linear; fixation (kg/ha) by the A‐value method = 50.1 + 0.852 N fixation by difference (r = 0.98, n = 15). Consequently, previous values cited for N fixation measured by the difference method for winter annual legumes in California may have been underestimated by about 40%.
Soybean Growth and Composition as Influenced by Soil Amendments of Sewage Sludge and Heavy Metals: Field Studies1
Authors: Ham G. E. , Dowdy R. H. 
Published: July 2010

AbstractThe potential influence of sludge‐borne heavy metals on crop growth and the food chain is a major concern with the utilization of municipal sludges in agricultural crop production. The objectives of this field research were to compare soybean plant growth and metal uptake of salt sludge‐borne metals and to determine the partitioning of these heavy metals into the various plant parts.Soybeans (Glycine max L. Merrill) were grown on soil to which air‐dried, anaerobically digested sludge was applied at rates of 25, 50, and 100 and 200 metric tons/ha. In addition, Zn, Cu, Ni, Pb, Cd, and Cr salts were added individually at levels equivalent to the quantity added in 50 metric tons sludge/ha. Sludge and metal salts were mixed into the top 20 cm of soil by roto‐tilling.Adding sewage sludge did not significantly influence soybean seed yield. The seed concentration of N, P, K, Zn, and Cd increased, whereas the Fe concentration decreased. Total uptake of elements, other than N, P, K, Ca, Mg, and Fe, was less than 1 kg/ha although the concentration increased significantly in some cases.Adding Cu salt increased seed yield and Cr salt decreased seed yield; otherwise metal salts did not influence yields. The metal salts of Ni, Zn, and Cd increased their concentration in mature seed.When mature plants were separated into leaves, stems, husks, or pods and seed, their analyses indicated that Zn was concentrated in the leaves, increasing up to 331 μg Zn/g leaf at the 200 metric ton/ha sludge rate (the Zn concentration in the stems and husks also increased with increasing sludge rates). In contrast, the Zn concentration of the seed leveled off at 100 metric tons sludge/ha. Cadmium and Cu were concentrated in the mature leaf tissue.Sewage sludge of the type applied in this study could be used as a source of P without yield reductions. These data did not show large increases of sludge‐borne metals in the seed.
Zinc and Cd Accumulation by Corn Inbreds Grown on Sludge Amended Soil1
Authors: Hinesly T. D. , Alexander D. E. , Ziegler E. L. , Barrett G. L. 
Published: July 2010

AbstractInbred lines of corn (Zea mays L.) differ in accumulation of Zn and Cd in leaves and grain. The capacity to accumulate Zn and Cd may be under genetic control. Twenty corn inbreds were planted in replicated control and sewage sludge amended, field, lysimeter plots to obtain information on uptake of Zn and Cd in leaves and grain.Sludge treatments had significantly increased concentrations of both Zn and Cd in the plow layer of soil. Mean total concentrations of Zn ranges from 68 to 454 mg/kg and of Cd from 0.3 to 20.6 mg/kg in the surface of Blount silt loam (Aerie ochraqualf, fine illitic, mesic) soil for control and maximum sludge treated plots, respectively. Concentrations of Zn and Cd in leaves of all inbreds were significantly increased on maximum sludgetreated plots. Zinc concentrations in leaves ranged from 61.8 mg/kg in B77 to 281.8 mg/kg in Oh43 and leaf Cd ranged from 2.5 mg/kg in R805 to 62.9 mg/kg in B37. Concentrations of Zn and Cd in grain of inbreds (except H99 for Zn and H99, Oh545, and R805 for Cd) were increased by higher concentrations of sludge borne metals in soil. Concentrations of Zn in grain varied from 33.8 mg/kg for H99 to 70.0 mg/kg for A619 and Cd varied from 0.08 mg/kg for R805 to 3.87 mg/kg for B37. Inbreds accumulating relatively high levels of Zn in leaf and grain tissue did not always accumulate high concen trations of Cd or vice versa. Mechanisms for controllin absorption of Zn and Cd appeared to be independent each other.
Radiation and Energy Balance of a Trickle‐Irrigated Lemon Grove1
Authors: Ben‐Asher J. , Sammis T. W. 
Published: July 2010

AbstractTrickle irrigation has become a widely used method. Its primary advantage in arid regions is that it saves water. However, because of its modernity, analytical and experimental results are minute compared to those for conventional irrigation methods. This study was conducted to evaluate the water saving potential and evapotranspiration from a trickle irrigated lemon grove (Citrus limon L. ‘Lisbon’). Detailed measurements of global, reflected, and net radiation and its dissipation above the plant, the unshaded sandy soil, and the area as a whole were made in the spring and summer of 1975. Two sources of radiant energy were observed: net radiation which accounted for 70% of the energy utilized in evapotranspiration and reflected radiation from the unshaded soil accounting for 30%. Experimentally the net radiation and evapotranspiration of the wet complex increased as the average net radiation and the evapotranspiration from the area as a whole decreased and vice versa. On the other hand, evapotranspiration and its ratio to evaporation from a class A pan were smaller than any previously reported values. Therefore, it is suggested that for these two periods the contribution of energy from the dry area to the wet did not reflect a specific disadvantage for trickle irrigation.
Effect of Mowing Height on Leaf Angle, Leaf Number, and Tiller Density of 62 Kentucky Bluegrasses1
Authors: Sheffer K. M. , Watschke T. L. , Duich J. M. 
Published: July 2010

AbstractInformation is needed on the effects of mowing management on Kentucky bluegrass (Poa pratensis L.) morphology. Recently released cultivars have a procumbem growth habit and, therefore, should be more tolerant of close mowing. A study was conducted on 62 Kentucky bluegrasses to determine the effects of mowing height on the leaf angle, leaf number, and tiller density. At each cutting height, the most significant difference among the cultivars was in the angle of the second leaf subtending the bud leaf. In general, when cutting heights were compared, most cultivars were more procumbent when mowed at 1.3 and 2.5 rather than 5.1 cm. Eighteen of the 62 cultivars, however, were not greatly affected by mowing because they varied by less than 6° across the cutting heights. Mowing height affected the leaf number per tiller. Most tillers had more leaves per tiller when mowed at the 2.5 cm height than at the other two heights. The numerical difference was small however, and this effect may only be of minor importance. Leafy cultivars tended to be more upright. As the cutting height decreased, tiller density increased; however, the cultivars varied as to which change in height brought about the most significant effect on tiller production.
Grazing of Grass and Cicer Milkvetch‐Grass Pastures with Yearling Calves1
Authors: Rumburg C. B. 
Published: July 2010

AbstractNitrogen fertilization rather than legumes is relied upon for increasing pasture and hay production in the Northern Rocky Mountains because of the difficulty of maintaining stands and the danger of bloat when legumes are used. Cicer milkvetch (Astragalus cicer L.) offers the promise of overcoming both of these objections. This study reports a comparison of N fertilized grass, and cicer milkvetch‐grass pastures (on an Aridic Agriboxolls) when grazed by three classes of cattle over a 3‐year period. Pasture quality was estimated by grazing with two testers each of long‐yearling steers, short‐yearling steers, and short‐yearling heifers which were about 14 and 7‐months old, respectively, at beginning grazing. Pasture production was estimated by addition or removal of stockers to harvest the pasture. Pastures were grazed 10 and rested 30 days in a four‐pasture rotation. The two pasture treatments were similar in average daily gain (0.99 kg/day); however, fertilized grass pastures produced a higher yield of digestible energy (15,000) than cicer milkvetch‐grass (13,000 Meal/ha), which resulted in live weight gains of 514 and 434 kg/ha, respectively. The older and heavier long yearlings consistently gained weight more rapidly (1.14 kg/day) than younger and lighter short‐yearling cattle (0.92 kg/day), but short yearlings produced more gain per hectare. Cicer milkvetch‐grass pastures may be an alternative for N fertilized grass pastures depending upon relative cost of N. The inclusion of cicer milkvetch added nothing to forage quality, and was 14% less productive than grass pastures fertilized with 1.12 kg N/ha.