AGRONOMIC PERFORMANCE OF Brachiaria humidicola (Rendle) Schweickt GENOTYPES IN THE MEXICAN HUMID TROPICS

Abstract

In the Mexican tropical region, where animal production is based on extensive grazing systems, the grasses of Brachiaria genus are important due to their good adaptation, high forage yield and nutritive value. The aim of this study was to evaluate forage yield, morfological composition and growth rate of 23 genotypes of Brachiaria humidicola plus one hybrid of Brachiaria. The study was carried out from June 2006 to May 2007, at Isla, Veracruz, México. Treatments were measured every 28 d during the rainy season and every 42 d during the dry and northern cold-front seasons, and distributed in a completely randomized block design with three replicates. There were significant differences in total forage yield (P ≤ 0.05), with genotype CIAT 679 cv. ‘Chetumal’ being the highest with 17 353 DM kg ha^-1 and CIAT 26159 the lowest with 11 104 kg DM ha^-1. The average seasonal forage yield distribution of the 24 genotypes was 83, 9 and 8 % during the rainy, northern cold-front and dry seasons, respectively. The highest average growth rate was recorded in June with 189 kg DM ha^-1 d^-1, which gradually decreased to 4 kg DM ha^-1 d^-1 in May. Leaves contributed most to forage yield, and the seasonal trend was northern cold-front > dry > rainy seasons, with averages of 77.6, 71.7 y 57.6 %, respectively.