Effects of irrigation and nitrogen fertilization on dry matter yield of panicum maximum cultivars

Abstract

This trial was carried out from September 6th (2000) to September 18th (2001) to evaluate the effects of irrigation and nitrogen fertilization on drymatter yield of five different cultivars of Panicum maximum. Five cultivars (Guiné, Coloniâo, Mombaça, Tanzània and Centauro) under three nitrogen rates (50, 75 and 100 kg/ha/cut of N), with and without irrigation were evaluated. The experimental treatments, the combination of a 5×3×2 factorial, was allocated in a completely randomized design with four replications. Irrigation brought about significant drymatter (DM) yield of all cultivars. In the rainy season (October/00 to March/01), highest DM yield was observed on plot receiving 75 and 100 kg/ha/cut of N. Under irrigation Mombaça cultivar was the most productive cultivar but without irrigation no difference was observed among the cultivars. During the dry season (May/01 to August/01), the drymatter yield of irrigated plots increased significantly as the nitrogen levels increased, whereas without irrigation difference between the rates of 50 and 100 kg/ha/cut of N was observed. A positive effect of irrigation was obtained from the final of dry season, as the temperature increased and probably the photoperiod was not a limiting factor. Forage management can be anticipated by reducing growth season from August, with DM yield from 1 and 2 t/ha, with N rate of 75 kg/ha/cut, to 3 t/ha, with the highest rate, in relation to the treatment without irrigation.