Performance of tropical forage grass (Brachiaria brizantha) dormant seeds under controlled storage

摘要

Brachiaria brizantha (palisade grass) is a tropical forage grass species showing a high dormancy level in freshly harvested seeds. The main aims of this research work were to analyse the release of seed dormancy under controlled deterioration as wellas to estimate viability constants, at moisture contents ranging from 3 to 20% and variable storage periods (from one hour to 1,550 days, at 40, 50 and 65 deg C). Twelve seed sub samples for each moisture content / temperature combination were sealed inaluminium foil packets and stored in incubators at those temperatures, until completed survival curves were established. Germination tests were performed on intact and scarified (H_2SO_4, 15') seeds. The hazardous effect of the high storage temperaturesseemed to be compensated by greater seed dormancy release, the best results being achieved at 50 deg C and 40 deg C for intact and scarified seeds, respectively, not taking into account seed moisture content. Estimated viability constants to predict seedlongevity were: K_E = 6.488, 8.795; C_W = 4.480, 4.852; C_H = 0.04750, 0.02114; C_Q = 0.001292, 0.000733 for intact and scarified seeds, respectively. The lowest moisture content limit for application of the viability equation at 65 deg C was 4.9%, unrelated to chemical scarification.