Dry matter allocation and chemical composition of brachiaria brizantha and decumbens 45 days after emergence / Alocação da matéria seca e composição química das braquiárias brizantha e decumbens, aos 45 dias após emergência

Abstract

This study evaluated dry matter allocation and chemical composition of brachiaria brizantha and decumbens under conditions of good nutrient supply. The study was conducted in the city of Coruripe, East Mesoregion of the state of Alagoas, in a medium-textured dystrophic red-yellow latosol. The experimental design was randomized blocks with five replications, and the plots consisted of five furrows of five meters in length, spaced 0.60 meters apart. Phosphorus was applied at the bottom the open furrows at a dose equivalent to 50 kg of P ha-1. Nitrogen and potassium fertilizers were applied at doses equivalent to 150 ha-1 when plants were approximately 5 cm tall. Evaluations of dry matter accumulation and allocation were carried out 45 days after plant emergence, when light interception by leaves was approximately 90%. Both species showed high growth rates, with an average shoot dry matter accumulation of 5.64 t ha-1, but brachiaria decumbens was about 25% more productive than brachiaria brizantha. There was no effect of the species on the percentage of dry matter allocation and about 50% of it was allocated to in the leaves. There was also no species effect on shoot crude protein content, which had an average of 106 g kg-1, enough to ensure good ruminal fermentation. Brachiaria decumbens had higher calcium, magnesium and sulfur contents compared to brachiaria brizantha, although adequate contents of these three nutrients were also found in brachiaria brizantha.