Resumen

MACHADO, R. Changes in the structure, population and composition of 19 Panicum maximum accessions under grazing conditions. Pastos y Forrajes [online]. 2012, vol.35, n.2, pp. 165-174. ISSN 0864-0394.

The objective of this work was to characterize the changes and trend of indicators related to the structure, population and composition in 19 Panicum maximum accessions under simulated grazing conditions. The rotations took place every 32-40 days in the rainy season and 60-70 days in the dry season, with grazing intensity of 80-135 animals/ha/day (the first two years) and 120-160 animals/ha/year (third year). A randomized block design was used with three repetitions. Although in all treatments the live shoots/dead shoots ratio decreased, this quotient was higher than one, for which the substitution rate of the shoots was favorable. In 84,2% of the treatments, the number of tufts increased as compared to the initial status. The weed percentage increased with the rotations, but none of the treatments reached an advanced deterioration status. In this indicator the giant types CIH-13, SIH-697, CIH-3, CC-1146 and SIH-10 stood out, with values that varied between 4,6 and 14,1%, as well as the medium types CIH-15 and Tardío pequeño with 10 and 12,3%, respectively. The evaluated germplasm was concluded to show adequate values, regarding the indicators related to the structure of the tuft, population and percentage of weed invasion; although a high contrast was identified between giant and medium types and within these groups. To analyze the other productive indicators is suggested in order to determine the most outstanding types, based on the results in all the included indicators.

Palabras clave : Panicum maximum; simulated grazing.

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