• Seedling Growth of Three Switchgrass Strains

      Perry, L. J.; Moser, L. E. (Society for Range Management, 1975-09-01)
      Seedlings of Pathfinder, Nebr. 28, and experimental ey switchgrass (Panicum virgatum L.) strains were grown in a growth chamber and harvested 1, 2, 3, 4, 6, 8, and 10 weeks following emergence for detection of seedling growth differences among strains. Leaf areas and dry weights of leaf blade and stem axis (stem and leaf sheath) generally increased significantly with each harvest from 4 to 10 weeks. Stem axis and leaf blade dry weights were significantly greater with Pathfinder and ey, respectively, than with Nebr. 28. Final leaf area was significantly greater with ey than with the other strains. Thus, Nebr. 28 (early-maturing) would be less competitive with weeds during establishment than Pathfinder or ey (both are late-maturing). Relative growth rate (RGR), net assimilation rate (NAR), and leaf area ratio (LAR) were similar for all strains, although at the first harvest Nebr. 28 had a lower LAR than the other two strains. RGR, NAR, and LAR generally declined with each successive harvest. The strains appeared to have the same capacity to produce above ground biomass but photosynthate partitioning differed as indicated by leaf and stem comparisons.
    • Thiourea Solution Temperature and Bitterbrush Germination and Seedling Growth

      Neal, D. L.; Sanderson, H. R. (Society for Range Management, 1975-09-01)
      Antelope bitterbrush (Purshia tridentata (Pursh) DC.) seed is commonly soaked in a solution of thiourea to break seed dormancy for spring planting. "Warm" thiourea solutions have been reported to cause seedling deformities. To determine what range of "warm" temperature solutions can cause deformities, four seed collections were treated at 18 temperatures (30 degrees F to 200 degrees F) in increments of 10 degrees F. Normal germination and seedling growth resulted between 60 degrees F and 140 degrees F. Below 60 degrees rate of germination declined slightly, but seedling growth was normal. Seedling deformities began to show up above 140 degrees F, and germination decreased rapidly. Deformities consisted of annular cracks around the hypocotyls and detached root caps. Solution temperatures between 60 degrees F and 140 degrees F are recommended.
    • Titratable Acids in Opuntia ficus-indica L

      Samish, Y. B.; Ellern, S. J. (Society for Range Management, 1975-09-01)
      Accumulation of acidity in spiny and spineless Opuntia joints fluctuated daily due to crassulacean acid metabolism (CAM) in Golan Height and coastal plain. The acidity reached higher concentrations in the young joints, especially during early morning hours, before the plants were exposed to sunlight. Changes in acidity were more pronounced in the chlorenchyma than in the water-accumulating tissues. These findings provide information on the rate and time of photosynthesis of these plants and may enable the feeding of livestock on Opuntia, while acid levels taken in by livestock are kept low to reduce a cause of diarrhea. The acidity is lower on sunny warm days, during late afternoons, in shriveled, old joints which had been exposed to full sunlight or were excised and stored in light. It may, therefore, be better to let cattle feed on the shriveled Opuntia before the start of the rainy season and use shrubs such as Atriplex halimus, which is better suited after onset of the first rain, as complementary perennial feed.
    • Trends of Nonstructural Carbohydrates in the Stem Bases of Switchgrass

      Smith, D. (Society for Range Management, 1975-09-01)
      Carbohydrate reserves in the stem bases of switchgrass (Panicum virgatum L.) reached their minimum percent in the spring growth, and in the regrowth after cutting, when the young tillers began to initiate their elongation (jointing). Cutting or grazing at this stage would weaken the plants as compared with cutting at the flowering stage, or later, when carbohydrate reserves have been restored to a high level.
    • Variability of Miserotoxin Concentration in Timber Milkvetch

      Majak, W.; McLean, A. (Society for Range Management, 1975-09-01)
      The variability in miserotoxin concentration of 120 individual timber milkvetch plants was determined in the bud, flower, and pod stages of growth on rough fescue grassland, parkland, and Douglasfir zone locations. Although a broad dispersion in miserotoxin levels was evident within each sampling unit of ten plants, the grassland samples exhibited the greatest toxicity with an exceptional level (10.17 +/- 1.13%) occurring during the bud stage. The bud stage of the parkland samples yielded intermediate concentrations (5.22 +/- 1.18%) while forest plants contained lower miserotoxin levels (4.08 +/- 0.95% to 2.49 +/- 0.47%). A decline in miserotoxin levels occurred during the bud-to-pod interval at the grassland and parkland sites, but significant differences were not apparent between the progressive stages of growth at the forest locations. The timber milkvetch toxicity patterns based on the variability of individual plants confirmed previously described trends derived from composite sampling.