• Germination Characteristics of Helianthus maximilianai Schrad. and Simsia calva (Engelm. and Gray) Gray

      Owens, D. W.; Call, C. A. (Society for Range Management, 1985-07-01)
      Germination characteristics of Maximilian sunflower (Helianthus maximiliana Schrad.) and awnless bushsunflower {Simsia calva Engelm. & Gray) Gray were evaluated at water potentials of 0, -.25, -0.50, -0.75, and -1.0 MPa under alternating temperature regimes of 10/20, 15/25, and 20/30 degrees C in controlled environmental chambers. Cumulative germination was greatest for both species at water potentials of 0 and -0.25 MPa in the 15/25 degrees C temperature regime. Germination total and rate were depressed for both species in the 10/20 degrees C regime. The 20/30 degrees regime depressed total germination but increased germination rate. The adverse effects of more negative water potentials (-0.75 and -1.0 MPa) were more pronounced at low temperatures for awnless bushsunflower and high temperatures for Maximilian sunflower.
    • Growth and Development of Pinegrass in Interior British Columbia

      Stout, D. G.; Brooke, B. (Society for Range Management, 1985-07-01)
      Pinegrass (Calamagrostis rubescens Buckl.) is an important source of forage on forested and clearcut ranges in interior British Columbia. The vegetative growth and development of this infrequently flowering grass was documented. This information is required to improve our understanding of pinegrass grazing resistance and in turn, of its grazing management. Numbers of tillers m-2 and number of leaves per tiller were counted at intervals during the growing seasons of 1978 and 1979. Leaf blade area was measured at intervals during 1978 and 1979. Tiller height was recorded during 1978, 1979, and 1982, while shoot weight was recorded at intervals during 1982. Pinegrass had up to 4 leaves per tiller, but on average only 3.2 leaves were present by the time growth ceased in July. Total leaf blade area was reached in July, and is largely comprised of 2 leaves. Total leaf blade area (y) was predicted from tiller height (x):y = 0.39375 + 0.051604x + 0.00419223x^2 (R2=0.97). A large proportion of leaf blade area was dead by the end of July. Tiller weight reached a maximum in July; it increased during May to July owing to an increase in number of leaves, leaf area, and specific weight of leaves. Growth analysis indicated that net assimilation rate (NAR), and relative growth rate (RGR) were high in mid-May and then gradually decreased to zero in July. NAR and RGR of pinegrass appeared typical for C3 plants.
    • Growth Parameter Differences between Populations of Blue Grama

      Samuel, M. J. (Society for Range Management, 1985-07-01)
      Samples of blue grama were obtained from disturbed and undisturbed areas of native rangeland in southeast Wyoming. Assumed 'slow-spread' populations were selected along a 50-year-old plowline from blue grama sod which had spread only a few centimeters into the plowed area. Assumed 'fast-spread' populations were selected from large plants within the plowed area. Control populations were selected at random from the undisturbed native range. Plants from 15 populations were grown in a dryland, uniform garden where basal spread was measured to determine if there were differences in rate of spread between populations of blue grama. Herbage production, plant height, and phenology were also compared. By the end of the second and fourth seasons of growth in the uniform garden, the fast-spread populations had spread 21 and 20% more than the slow-spread populations. The random populations were 17 and 11% larger than the slow-spread populations during the same year. The fast-spread and random populations were not different.
    • Automated Rainout Shelter for Controlled Water Research

      Ries, R. E.; Zachmeier, L. G. (Society for Range Management, 1985-07-01)
      An automated rainout shelter was constructed at the Northern Great Plains Research Laboratory, Mandan, N. Dak., for use in conducting controlled water research to gain a better understanding of soil-plant-water relationships. The design and construction criteria were developed to accommodate many components that were commercially available. The primary components are: (1) foundation, (2) steel I-beam rail, (3) roller mechanism, (4) rainout shelter structure, (5) drive mechanism, (6) electrical control system, and (7) irrigation system. Wind, temperature, and precipitation sensors activate movement of the shelter to cover a plot area 11.5 × 30.3 m (38 × 100 ft), resulting in a modification of the selected environmental conditions. After inactivation of the sensors and a time delay, the rainout shelter automatically returns to its rest position, ready to repeat its cycle when the sensors are reactivated.