Stapf colhidas por varredura manual ou mecanizada Components of seed production of two cultivars of Brachiaria

Abstract

The objective of this study was to evaluate the seed production compounds and productivity of seeds of cvs. Marandu and Xaraés of Brachiaria brizantha (Hochst. ex A. Rich.) Stapf harvest by manual or mechanical sweeping. There was used completely randomized design, with 20 replications, quantifying reproductive tillers density, number of racemes/tiller, the length of basal raceme, number of spikelets / raceme, and the pure seed productivety/ha, using squares of 1m2 in the seed production field with 320 and 80 ha sowing with cvs. Xaraés and Marandu, respectively, in the Sagrillo Farmer, Barreiras, western Bahia State-Brazil, with samples occurring from May to Jun of 2008. The seeds harvest manually handle were analyzed in pureness, germination, and seedling vigor under three depths in sand box (1, 2 and, 4 cm). The data were statistically analyzed by ASSISTAT program, assuming as significative differences between averages when F values were lower than 0.05 by the test Tukey. The cv. Xaraés showed more reproductive tiller density (206/m2), higher number of racemes (7.25) and more length per raceme (15.8 cm) than the cv. Marandu (100 tillers/m2, 6.80 racemes/tiller e 14.9 cm/raceme, respectively). However, the number of spikelets by raceme was the same (50.8 units). The pure seed productivity was higher in the cv. Xaraés (188 kg/ha) than the cv. Marandu (154 kg/ha). Germination in sand was not different between cultivars, harvest method, or depth of seed. However, seedling development decreased with increase of seed depth from 1 and 2 cm to 4 cm. The cv. Xaraés was superior considering the seed production compounds, resulting in higher seed productivity, while quality did not differ between cultivars or harvest method.