TURNOVER AND TILLER POPULATION STABILITY OF Panicum maximum CV. ‘MOMBAZA’ GRASS HARVESTED AT DIFFERENT CUTTING INTERVALS

Abstract

The objective of this experiment was to evaluate tiller density, tiller turnover and tiller population stability of Panicum maximum Jacq. cv. ‘Mombaza’ grass, harvested at three cutting intervals (CI; 3, 5 and 7 weeks) throughout a 12-month period comprising the “dry season” (Nov 10, 2006 to Jun 09, 2007) and the “rainy season” (Jun 10-to –Nov 06, 2007). Treatments (CI) were assigned to 12 experimental units (17.5 m² plots) according to a complete randomised block design with four replications. Tiller population densities were greater for the 3-weeks CI during the dry season (428 tillers m^-2) and for the 3 and 7-weeks CI during the rainy season (413 and 394 tillers m^-2, respectively). During the rainy season tiller turnover process was more intense and characterised by the highest rates of tiller appearance (38.0 vs. 4.6 tillers 100/tillers x month) and death (32.9 vs. 6.4 tillers/100 tillers x month), and lowest survival (67.1 vs. 93.6 tillers 100/tillers x month). Cutting intervals of 3 and 5-weeks averaged population stability indexes close to one, but the 7-weeks CI was less than one. During the dry season there was a lower tiller turnover, with lower tiller appearance and death rates but higher tiller population stability, than during the rainy season when the tiller turnover increased. ‘Mombaza’ grass may be harvested every 3 and 5 weeks without compromising its tiller population stability. Th e 7-weeks CI did not allow an effi cient replacement of dead tillers thus leading to instability of the tiller population.