Management of “common” Brachiaria humidicola seed production crops: I – Effect of nitrogen doses

Abstract

Low yields often obtained from commercial seed production crops of ‘common’ Brachiaria humidicola, a tropical forage grass used as cultivated pasture, result from an association between short period of seed retention in the inflorescences and a marked synchronism of inflorescence emergence. In consequence, the period of seed availability for harvesting is brief. The possibility of staggering seed production among crops would allow extension of the harvest period and, hence, of equipment use. This work was carried out to evaluate the influence of N doses on this period and to discuss the possibility of using this practice to extend harvest period. Five N doses (0; 25; 50; 75 and 100 kg ha-1de N) were applied as urea top-dress at the start of the 2000’s raining season. Seed samples were collected on the 66th, 69th and 72nd days after N application. Treatment effects were evaluated in terms of potential pure seed yield and several seed yield components. The period of highest availability of pure seed to harvest and the extension of this period varied according to the N dose applied. The highest potential yield (295 kg ha-1) resulted from the application of 75 kg ha-1de N. The maximum yield resulted from the application of 50 kg ha-1de N was 16 % lower and was achieved four days later. Even at the yield reduction cost , the use of different N doses may contribute to risk and cost reductions in commercial seed production systems of ‘common’ Brachiaria humidicola.

Keywords

• colheita de sementes
• componentes da produção de sementes
• degrana
• maturação de sementes
• uréia