MORPHOGENIC CHARACTERISTICS AND THEIR INFLUENCE ON THE HERBAGE YIELD OF MOMBAZA GRASS, HARVESTED TO DIFFERENT CUTTING INTERVALS

Abstract

The aim of this study was to evaluate tissue turnover and herbage yield per cut of Mombaza grass (Panicum maximum Jacq.), harvested to three cutting intervals (3, 5 and 7 weeks), during one year, in the rainy (Jun 10 to Nov 06 2007) and the dry (Nov 10 2006 to Jun 09 2007) season. Treatments were allocated in 12 paddocks of 17.5 m2 using a randomized complete block design, with four replications. The 3-weeks cutting interval (CI) had the highest leaf appearance rate (0.185 leaves tiller-1d-1), during the study (P<0.01). There was higher stem elongation rate (188%) and leaf elongation rate (182%) during the rainy season (P<0.05). During the dry season the leaf senescence rate was minimum (0.6 mm tiller-1 d-1) and highest during the rainy season (P<0.01) with 7-weeks CI (19.7 mm tiller-1 d-1). The highest net growth rate (144%) was recorded during the rainy season (P<0.01). Lower herbage yield and growth rate were observed during the dry season (P<0.01), but leaves contribution to the herbage yield was higher than 82% in all CI. During the rainy season, the higher herbage yield per cut and growth rate were recorded with 5 and 7-weeks CI (P<0.01), with lower leaves contribution to herbage yield (59 and 51%, respectively). Mombaza grass showed seasonality in tissue turnover, with higher sward dynamics during the rainy season and it most be harvested every 3 weeks during the rainy and every 5 weeks during the dry season in order to reduce the losses by leaf senescence and improve herbage production and utilization.