[Effects of water deficit in spring-summer on the productive characteristics of an artificial prairie of the tenth region]
1993
Trivino M, Marcela Ivonne
At the Oromo Agricultural Experiment Station of the Agrarian and Forestry Sciences College, University of Chile, four pluviometric regimes were evaluated in a rye grass and white clover sown pasture, in order to determine their effects on the production, botanical composition and nutritive quality of the forage. Every treatment was applied to four plots of 4 m2 each one. These treatments were defined as Current Year (AA), Optimal Year (AO), Suboptimal Year (ASO) and Very Dry Year (AMS) and received 76.3, 78.0 59.5 and 45.5% of the rainfalls occurring in a normal year, respectively, Excepting the Control (AA), the pluviometric regimes were simulated by watering and plastic covers for adjusting the rainfall amount to the amount established weekly, for each treatment. The dry matter production was determined by pasture cutting, the botanical composition by utilizing the point quadrant method (Daguet and Poissonet, 1971) and the forage quality by crude protein determinations (N x 6,25), cell wall content (NDF) and in vitro organic matter digestibility (OMD). The results of dry matter production determinations showed significant differences and were directly related with the moisture level. AO reached a production of 10,525 kg DM/ha/year, followed by ASO, AA, AMS with 9,267, 7,359, 7,318 kg DM/ha/year, respectively. The botanical composition showed a high variability within the treatments, with important seasonal variations. In some evaluations, only the presence of rye grass differed statistically showing the least contribution in the AMS treatment during the summer. Also, a higher degree of weediness was associated with high hydric stress. With regard to forage quality, only the OMD revealed variations by effects of the treatments, decreasing its value when the moisture sprees was higher
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