INFLUENCE OF CUTTING FRECUENCIES ON THE PRODUCTION OF BIOMASS AND CHEMICAL COMPOSITION OF THE CULTIVAR OF Pennisetum purpureum IN TWO LOCALITIES. BUGABA, CHIRIQUI, PANAMA. 1999-2002.

Abstract

This work was performed during the period 1999 to 2002 in Volcan and Buena Vista at Bugaba, Chiriqui, Panama. Volcan is located at 1,250 masl with a pluvial precipitation of 3,100 mm and a temperature of 20°C, while Buena Vista is located at 850 masl with a temperature average of 21°C and a pluvial precipitation of 5,900 mm. Cutting frequencies effects were studied (70, 90, 110, 130 d) on dry matter (DM) production and chemical composition of cultivars of Pennisetum purpureum (CT-22, 115, 169 and Taiwan A-144). Two stems with 0.35 m long were planted with 0.15 m depth and 0.75 m among rows and grooves. At planting, 45, 40 and 25 kg of N, P₂O₅, K₂O/ha/year, respectively, were applied. Then, a cut of equal length was carried out and 275 kg of N/ha was applied, fractionally to each cut, plus 40 kg of P₂O₅/ha/year and 25 kg of K₂O/ha/year at the beginning of the rain season. A split plot (Randomly blocks) statistical analysis, with three repetitions, was utilized, and the main plot was constituted by locations, subplots, cultivars and sub subplots, and the cutting frequency. A generalized lineal model was used for analyzing. The production of DM increased significatly (P<0.01) regarding age of cutting and varied from 2.56 to 15.96 tons of DM/ha/cut on days 70 and 130, respectively. Crude protein was different among ages of cutting varying from 9.76 to 6.71% on days 70 and 130, respectively. Cuban cultivars CT-22, 115 and 169 showed acceptable productions of DM. Similar production was observed between CT-22 and Taiwan A-144 probably because CT-22 does not have hairs. Analyzing forrage production, persistancy and quality of harvested materials, it is concluded that the ideal harvest frequency for the Pennisetum purpureum occured on days 90 and 110 in Volcan and Buena Vista, respectively.