Previous grazing or clipping affects seed of Indian ricegrass
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Authors: A. B. Orodho, R. L. Cuany, and M. J. Trilca
Date: 1998
Journal: Journal of Range Management
Volume: 51
Number: 1
Pages: 37-41
Summary of Methods: Indian ricegrass (Oryzopsis hymenoides) plants were clipped at anthesis in a field study that compared the seed production, weight, and germination of plants that were exposed to heavy grazing or protection from grazing for the past 50 years. Grazed and ungrazed strains of Indian ricegrass had similar seed characteristics and responded to increasing clipping intensities by decreasing seed production. In a garden study that compared the plant response of the previous two strains of Indian ricegrass with two other commercially available cultivars, Nezpar and Paloma, Nezpar produced the most seed, the two field strains were intermediate, and Paloma produced the least seed. However, severe clipping treatments reduced seed production from all varieties of Indian ricegrass. Nezpar seeds were the lightest and had the greatest viability, while Paloma seeds were the heaviest and had the lowest viability and the two field strains again were intermediate. These results suggest that long-term heavy grazing has not altered the seed production or germinability of the field strains of Indian ricegrass and based on the results of the garden study the authors recommend the use of the commercially available Nezpar cultivar and not the Paloma cultivar in this area.
Article Summary / Main Points: None
Vegetation Types:
MLRA Ecoregions:
Agrovoc Control Words: Riparian zones Rangelands Wildlife
Article Review Type: Refereed
Article Type: Experimental Research
Keywords: indian ricegrass, oryzopsis hymenoides, ecotypic variation, protection, defoliation, germination, viability
Annotation: At the Chaco Canyon site in New Mexico, 10 non-defoliated plants of native Indian ricegrass in a natural community were selected at random from each of 6 plots in 2 study areas (grazed and protected). These plots were located on 3 topographic positions (hilltop, hillside, and swale) within each of 2 areas: heavily-grazed for 50 years or more, and protected inside the national monument for 50 years. 4 defoliation intensities (0, 30, 60, and 90% removal of photosynthetic tissues) were each applied to 4 Indian ricegrass tussocks selected at random. Defoliation was done by clipping plants the anthesis stage in early June 1984, and clipping was repeated at the same phenological stage in 1985. At the Cortez site in Colorado, 2 collections (grazed and ungrazed) and 2 cultivars (Paloma and Nezpar of Indian ricegrass were transplanted in late April from field material. 2 defoliation treatments (unclipped and clipped) were used.
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