Now showing items 7301-7320 of 20719

    • Factors affecting dietary preferences for genotypes of a hybrid wheatgrass

      Truscott, D. R.; Currie, P. O. (Society for Range Management, 1987-11-01)
      Interspecific hybridization of grasses represents a valuable plant breeding procedure for developing new species with superior grazing value for livestock. Evaluations were made of the hybrid cross between quackgrass (Elytrigia repens [L.] Beauv.) × bluebunch wheatgrass (Pseudoroegneria spicata [Pursh.] Scribn and Smith) to determine how animal preferences for these hybrids were influenced by grazing season and year. Significant differences in the preference shown by steers as measured by bite counts in 1981 and percent utilization (P<0.01) in 1982 existed among the 46 clonal lines for each of the 2 successive years. Preference rankings for lines selected the first year were not identical to those selected a second year although lines with high preference rankings the first year were generally preferred the second year. A clonal line, designated line 30, was most preferred in 7 of 8 subtrials in 1981 and ranked in the top 3 preferred plants in all trials in 1982. There was a 4-week period in early summer when preference differences were minimal. It was attributed to the abundant regrowth on all lines at this time and was found to have a significant (P<0.01) effect on steers' dietary choices.
    • Factors Affecting Fill and Consequently Overnight Shrinkage in Range Cattle

      Wagnon, K. A.; Rollins, W. C. (Society for Range Management, 1962-05-01)
    • Factors Affecting Forage Consumption by Cattle in Arizona Ponderosa Pine Forests

      Clary, W. P.; Ffolliott, P. F.; Larson, F. R. (Society for Range Management, 1978-01-01)
      Forage consumption was significantly correlated with forage production and tree density, but not with steepness of slope, rockiness of soil, or distance from water. This suggests that good range management practices can effectively distribute livestock use.
    • Factors Affecting Forage Intake by Range Ruminants: A Review

      Allison, C. D. (Society for Range Management, 1985-07-01)
      Variation in voluntary forage intake is undoubtedly the major dietary factor determining level and efficiency of ruminant production. This variation is largest and least predictable for grazing ruminants. Range ruminant productivity and efficiency is relatively low due, in part, to intake limitations; therefore, productivity could probably be increased most by increasing intake. Most available literature points to digestibility and rate of ingesta passage and reticulo-rumen fill as primary mechanisms of intake regulation in range ruminants. Body size and physiological status of ruminants appear to have the largest effect of animal-related factors in governing level of voluntary intake. Kind and amount of supplementation, forage availability, and grazing intensity are major management-controlled variables affecting intake by domestic range ruminants.
    • Factors Affecting Germination, Emergence and Establishment of Sand Bluestem

      Stubbendieck, J.; McCully, W. G. (Society for Range Management, 1972-09-01)
      Response of sand bluestem seed units (florets) to three rates of cotton-bur mulch and treatment with an organic mercury pathogenicide was measured by germination, emergence and establishment. All rates of cotton-bur mulch improved soil moisture conditions, but heavier rates formed a physical barrier to the emergence of grass seedlings. More than three times as many plants became established from florets treated with a pathogenicide than from untreated florets.
    • Factors Affecting Mesquite Control with Tordon 225 Mixture

      Sosebee, R. E.; Dahl, B. E.; Goen, J. P. (Society for Range Management, 1973-09-01)
      The influence of various site characteristics was studied for Tordon 225 Mixture effectiveness in honey mesquite control in the Rolling Plains of Texas. Tordon 225 Mixture was commercially applied in 1970 at 0.5 lb a.e./acre under an experimental label for Texas. Generally, soil temperature (18-inch depth) above 75 degrees F, relatively low soil water content (0 to 6-inch depth), and tree height (less than 8 ft) were most influential in the root mortalities obtained in this study.
    • Factors affecting private rangeland lease rates

      Vantassell, L. W.; McNeley, S. M. (Society for Range Management, 1997-03-01)
      Private rangeland lease rates have been used historically as an indication of the price of public grazing lease rates. The ability of these prices to adequately reflect short-term fluctuations in the rancher's ability to pay for forage has been questioned by policy makers and researchers. Multiple regression techniques were used in this study to evaluate how responsive private rangeland lease rates have been to short-term (yearly) fluctuations in market conditions. Independent variables included yearling prices, cattle numbers, hay prices, production cost index, land prices, forage condition index, and the previous year's lease rate. Yearling prices lagged 1 year, hay prices, production cost index lagged 1 year, and lease rates lagged 1 year statistically (P < 0.10) explained lease rates. The previous year's lease rate was the most influential explanatory variable, with more than half of the previous year's lease price reflected in the current year's rate. Statistically significant (P < 0.10) differences in lease rates were also found between western regions.
    • Factors Affecting Resistance to Heavy Grazing In Needle-and-Thread Grass

      Peterson, R. A. (Society for Range Management, 1962-07-01)
    • Factors affecting root of stem cuttings of salt desert shrubs

      Richardson, S. G.; Barker, J. R.; Crofts, K. A.; Van Epps, G. A. (Society for Range Management, 1979-07-01)
      Several variables were identified that affect rooting of stem cuttings of fourwing saltbush (Atriplex canescens), cuneate saltbush (A. cuneata), shadscale (A. confertifolia), spiny hopsage (Grayia spinosa) and greasewood (Sarcobatus vermiculatus). Differences in rooting were found among different individuals within the same population. Rooting varied with season of collection and with concentration of hormone application. There was an interaction between the effects of season of collection and concentration of applied hormone. Longer fourwing saltbush cuttings rooted better than shorter ones, and woody basal portions of new leaders rooted better than herbaceous tips. Sex of dioecious saltbush species was generally not an important factor in rooting success. Cuttings from greasewood plants grown in a greenhouse rooted better than field-collected cuttings.
    • Factors Affecting the Nutritive Value of Range Forage

      Oelberg, K. (Society for Range Management, 1956-09-01)
    • Factors affecting Utah ranch prices

      Rowan, R. C.; Workman, J. P. (Society for Range Management, 1992-05-01)
      A total of 341 Utah rural land sales occurring between 1980 and 1987 were analyzed to identify and quantify the determinants of Utah rangeland and ranch prices. Two factors statistically influenced average sale price (/hectare and/or /AUM): number of hectares sold and whether buildings were included in the sale. Regression analysis incorporated statistically significant (P < 0.05) explanatory variables into a predictive equation that expressed total ranch sale price as a function of number of deeded AUMs, building value, year and month of sale, number of leased AUMs, distance to nearest town, recreation influence, and size of parcel sold. The regression model produced an adjusted R2 = 0.91. Value of buildings and number of deeded AUMs explained most of the variability in total ranch sale price.
    • Factors Affecting Utilization of Mountain Slopes By Cattle

      Cook, C. W. (Society for Range Management, 1966-07-01)
      Many factors affect the utilization of mountain terrain by cattle and these factors are interrelated and exert their influence in a complicated manner. Actual use obtained under good management is the most accurate method of determining the utilization obtainable on a particular mountain slope.
    • Factors affecting weeping lovegrass seedling vigor on shinnery oak range

      Matizha, W.; Dahl, B. E. (Society for Range Management, 1991-05-01)
      Low vigor of seedlings and stand failures plague many revegetation efforts in semiarid and arid rangelands. Phototoxicity, sandbur (Cenchrus incertus M.A. Curtis) competition, seedbed preparation (plowing vs. disking), and nitrogen (N) fertilization were studied as reasons for low vigor of Ermelo weeping lovegrass [Eragrostis curvula Schrad.) Nees] seedlings on sand shinnery oak (Quercus havardii Rydb.) range in west Texas. Oak leaf residue and sandbur-dominated grass residue extracts did not affect seed germination and initial shoot growth of lovegrass seedlings. However, these residue extracts reduced root length 92% and 21%, respectively. Survival of weeping lovegrass seedlings was not affected by even 65 sandbur plants/m2. But, herbage yield was reduced 65, 72, and 79% with 30, 45, and 65 sandbur plants/m2. Early in the growing season, unfertilized plowed (P) plots had 5.6 ppm N in the 10-20 cm soil layer compared to a maximum of 3.9 ppm on other seedbed treatments. In the surface 10 cm, the P plots had less N than the disked plots. Surface-applied N fertilizer accumulated in the upper 10 cm of soil and promoted weed growth without improving weeping lovegrass stands or seedling vigor. Weeping lovegrass seedling vigor was greatest on P and least on disked plots. Thus, plowing buried weed seeds better, put resident N more deeply into the soil for better root uptake, removed allelopathic residues from seedling contact better, and provided for much higher seedling vigor than the disked seedbeds.
    • Factors Causing Hollow-Crown or Ring Grass Patterns

      White, E. M. (Society for Range Management, 1989-08-01)
    • Factors Causing Losses during the Establishment of Surface-sown Pastures

      Campbell, M. H.; Swain, F. G. (Society for Range Management, 1973-09-01)
      Seeds of four pasture species were surface-sown in winter, spring, and summer and losses of seeds, seedlings, and plants during germination, radicle-entry, establishment, and survival noted under various treatments. On an unprotected soil surface losses during germination, radicle-entry and establishment were least in winter and greatest in summer. Dead plant cover on the surface reduced losses during germination and radicle-entry in the summer, while sub-irrigation reduced losses during germination in summer and radicle-entry and establishment in spring and summer. Losses during survival were heavy in all seasons, usually because of moisture stress. Other reasons for losses included harvesting of seeds by ants, damage by soil fauna, residual herbicides, and competition from weeds.
    • Factors Increasing Boll Rots and Fatty Acids in Cotton Seed

      Streets, R. B.; Boyle, Alice; Simonsen, Helen; Department of Plant Pathology; Department of Plant Pathology; Department of Plant Pathology (College of Agriculture, University of Arizona (Tucson, AZ), 1957)
    • Factors Influencing 14C Ages of the Pacific Rat Rattus exulans

      Ragano Beavan, Nancy; Sparks, Rodger J. (Department of Geosciences, The University of Arizona, 1998-01-01)
      An isotopic database for the Pacific/Polynesian rat (Rattus exulans) and foods that it scavenges is used to examine diet-induced 14C age variation in omnivores. We discuss a suite of 26 Delta-14C determinations and 13C and 15N analysis for modern Pacific/Polynesian rat bone gelatin and available food items from Kapiti Island, New Zealand (40 degrees 51'S, 174 degrees 75'E). These analyses provide the first isotopic data for modern specimens of the species, collected as part of a larger project to determine potential sources of bias in unexpectedly old 14C age measurements on subfossil specimens of R. Exulans from New Zealand. Stable C, N and 14C isotopic and trapping data are used to trace carbon intake via the diet of the rats in each habitat. Data from specimens linked to five specific habitats on the island indicate that modern populations of R. Exulans are not in equilibrium with atmospheric values of Delta-14C, being either enriched or depleted relative to the atmospheric curve in 1996/97, the period of collection. The Delta-14C values recorded for R. Exulans are associated with diet, and result from variation in Delta-14C values found in animal-protein food items available to a scavenging omnivore. The titer of carbon deviating from atmospheric values is believed to be derived from the essential amino acids in the protein-rich foods of the rat diet. Present evidence suggests that the depletion required to affect 14C ages limits the possibility that diet introduces dramatic offsets from true ages. Marine diets, for example, would have a variable effect on ages for terrestrial omnivores, contraindicating the application of a standard marine correction for such specimens. We suggest that to identify the extent to which diet may influence the 14C age in a given specimen of terrestrial omnivore, the separation and dating of essential amino acids vs. A nonessential amino, such as glycine, be applied.
    • Factors Influencing Bitterweed Seed Germination

      Whisenant, S. G.; Ueckert, D. N. (Society for Range Management, 1982-03-01)
      Bitterweed seed germination exceeded 90% at constant temperatures between 20 degrees and 25 degrees C and more than 65% between 15 degrees and 30 degrees C in a controlled environment chamber. Seeds germinated equally well in light and dark conditions. Germination percentages of seeds in aqueous media with a pH range of 5 to 9 were significantly different, but the range of germination (91 to 97%) probably is not sufficient to affect distribution. However, a decrease in water availability significantly decreased bitterweed seed germination. Viability of bitterweed seed did not change significantly after 39 months dry storage at room temperature, but was significantly reduced at 47 months.
    • Factors Influencing Broadcast Seeding in Bunchgrass Range

      Nelson, J. R.; Wilson, A. M.; Goebel, C. J. (Society for Range Management, 1970-05-01)
      The objective of this work was to evaluate problems of broadcast seeding perennial grasses on steep or rocky rangelands that cannot be seeded by conventional methods. Depredation of seeds by rodents and birds limited the effectiveness of broadcast seedings but not of drilled seedings. Drilled seeds remained in relatively constant and favorable soil moisture, and carried on metabolic processes rapidly and without interruption. Broadcast seeds were exposed to rapidly fluctuating moisture conditions which resulted in the frequent starting and stopping of germination processes. In drilled seedings, seven perennial grasses gave good seedling stands. In broadcast seedings, Sherman big bluegrass (Poa ampla) gave the best seedling stands. Ineffectiveness in controlling cheatgrass (Bromus tectorum) and other competing species was the main obstacle to seedling establishment. Successful establishment of seeded grasses appeared to be related to rate of penetration of seedling roots.
    • Factors influencing crown placement of oats (Avena sativa L.)

      Ries, R. E. (Society for Range Management, 1999-03-01)
      The depth of the grass crown nodes in the soil influences the susceptibility of the crown to environmental and management conditions which can affect grass establishment success and grain and forage yield levels. A controlled environment experiment was conducted to quantify the effect of planting depth (38 and 76 mm), temperature (25 and 10 degrees C), and light (full light [900 micromoles m(2) sec(-1)] and shaded at 55% full light [500 micromoles m(2) sec(-1)] on the elongation of oat (Avena sativa L. 'Valley') seedling internodes and the resulting final crown placement. The mesocotyl and 1st leaf internode increased in length with increased planting depth with no significant interactions. The length of the 2nd leaf internode increased more when developed under 25 degrees C temperatures than under 10 degrees C (significant temperature X depth interaction). However, the 2nd leaf internode elongated more under low light (55% full light) compared to full light (significant light X depth interaction). The 3rd leaf internode length was the same for the 38 and 76 mm planting depths when developed at 10 degrees C and under 55% full light. At 10 degrees C-full light and 25 degrees C-55% light, the deep planting depth resulted in increased 3rd leaf internode elongation, while at 25 degrees C-full light, the 3rd leaf internode was longer when developed from 38 mm planting depth (significant temperature X light X depth interaction). The ultimate elongation of these internodes resulted in the depth and structure of the final oat crown. This study points out the importance of naming and knowing each internode since the internodes do not respond in similar manner to environmental conditions. When all factors resulting in oat crown depth location and structure are considered, one expects crowns of oat seedlings developed under 10 degrees C to contain 4 nodes somewhat separated and crowns containing only 3 nodes more widely separated under temperature conditions of 25 degrees C. The most compact crown developed under reduced light conditions, from 38 mm planting depth, and a temperature of 10 degrees C. This information concerning the morphology of crown structure and location is expected to be similar for annual and perennial forage grasses with an oat type seedling morphology when seeded at similar temperatures, light intensities, and planting depths.