Resumen

MANRIQUE LUNA, Diana Leidy  y  CARULLA FORNAGUERA, Juan Evangelista. Leaves per tiller as the criterion to determine optimum defoliation frequency in pastures of Brachiaria decumbens. Rev. Fac. Nac. Agron. Medellín [online]. 2020, vol.73, n.2, pp.9151-9163. ISSN 0304-2847.  https://doi.org/10.15446/rfnam.v73n2.77292.

Two studies were performed to establish the best defoliation frequency in Brachiaria decumbens using the number of leaves per tiller as a criterion. In the first study, 3,500 tillers with 2, 3, 4, 5, or 6 leaves were collected in 10 farms. The number of green, senescent, and dead leaves was counted. A pooled sample of tillers by each farm with a given number of leaves was analyzed for nutritional quality; a complete randomized block design was used for this study. In a second study, it was implemented a complete ramdomized design with repeated measures over time (2 defoliations), and the effect of defoliating B. decumbens at 3, 4, or 5 leaves per tiller on its growth, dry matter yield, and nutritional quality were evaluated. In the first study, all leaves remained green until the tiller had 3 leaves. At the fourth leaf, few tillers (2.3%) had senescent leaves, but at 6 leaves, most tillers had senescent (40.6%) or dead (24.4%) leaves. Crude protein and digestibility decreased as the number of leaves in a tiller increased (P<0.001). In the second study, the rate of dry matter accumulation was the highest for plots defoliated at 4 leaves (P<0.05). Green stems (43.9%) represented a larger proportion of dry matter than green leaves (31.4%), and their proportions were similar among treatments. Crude protein and digestibility of stems decreased as the number of leaves per tiller increased (P<0.001), but the quality of leaves was similar. These findings suggest that these pastures should be defoliated at 4 leaves per tiller.

Palabras clave : Brachiaria grass; Grazing management; Signal grass; Tropical grasses; Urochloa decumbens.

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