Browsing Journal of Range Management, Volume 28, Number 5 (September 1975) by Title
Now showing items 22-25 of 25
Thiourea Solution Temperature and Bitterbrush Germination and Seedling GrowthAntelope 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 LAccumulation 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 SwitchgrassCarbohydrate 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 MilkvetchThe 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.