Germination and seed ecology of Buchenavia tomentosa Eichler (Combretaceae)

Germinação e ecologia de sementes de Buchenavia tomentosa Eichler (Combretaceae)

Abstract:

Buchenavia tomentosa produces fruits with ecological function for Cerrado’s fauna. The aims of this paper were to quantify seed germination and behavior on thermal conditions and explain about water absorption of dispersal structure in B. tomentosa seeds. Ripe fruits were pulped, the endocarp removed, and seeds used in the germination tests at temperatures of 10 to 45 °C. Seeds were placed in rolls of filter paper and then placed in germination chambers, at twelve hours of photoperiod. Germination models at sub and supra optimal temperatures were made from the germination rate (T_g), from the time to germination of 50% of the seeds (t₅₀). Germination speed index (GSI), measurements of shoot and root lengths and dry mass at each temperature were obtained. The water imbibition curve of seed with or without endocarp adhered and scarified or not was made and other samples were tested for emergence in sand. Cardinal temperatures were: base temperature (T_b) of 9.23 °C; maximum temperature (T_max) of 44.6 °C; optimum temperature (T_o) of 29.24 °C and thermal time of 89.71 °C.days. Seedlings showed higher GSI, root and aerial part length and higher root dry mass at the optimal temperature. The endocarp retards, but does not prevent water absorption and emergence.

Index terms:
mirindiba-do-Cerrado; boca-boa; thermal time model; germination model; endocarp