Effect of frequency of defoliation on dry matter yield of botanical fractions of king grass purple (Pennisetum purpureum x Pennisetum typhoides)

In the western of Venezuela, in an area characterized as very dry tropical forest, an experiment was conducted in order to evaluate the defoliation frequency effect on yield of dry matter (DM) of botanical fractions of purple King grass (Pennisetum purpureum x Pennisetum typhoides). It was determined the yield of DM in leaves (DMSH, g.plant(-1)), internodes (DMSE, g.plant(-1)), nodes (DMSN, g.plant(-1)), total (DMST, g.plant(-1)) and leaf: stem (RHT) under three defoliation frequencies (30,45 and 60 days). A completely randomized design was used with seven replications. The results showed a significant effect (P<0.05) in the frequency on DMSH, DMSE, DMSN and DMST, while it did not affect the RHT. The highest yields of DM botanical fractions were obtained when the plants were harvested every 60 days (170.4, 32.5, 7.52 and 210.43 g.plant(-1) for DMSH, DMSE, DMSN and DMST, respectively). The RHT gained an average of 7.25. The largest proportion in the composition of the plant was leaf (86.98%) followed by internodes (10.14%) and knots (2.88%). The best behavior of the purple king grass was obtained when the plants were harvested to 60 days.