Seed germination and chlorophyll-a fluorescence emission in plants of Randia armata (Sw.) DC. (Rubiacea) from thermal shock

Abstract

Understanding how reproductive aspects of seed germination may reflect adjustment and/or adaptation to fire in Cerrado species is importance in order to guide policies and conservation actions to this biome. The aim of this study was to evaluate the effect of seed heat treatment on germination and physyological status of Randia armata (Sw.) DC. For this, seeds of this species were submitted to temperatures of 25 ° C-Control, 90 ° C, 120 ° C and 150 ° C for 5 minutes. Subsequently the seeds exposed directly to the thermal shock were seeded in Germitest® paper and deposited in a germination chamber (B.O.D). After 60 days of sowing (DAS) the seeds were evaluated for the percentage of germination (G%) and at 150 days after germination the first pair of leaves of the plants were evaluated for chlorophyll-a fluorescence emission (FChlo-a). The G% of the seeds exposed to the high temperatures reduced in average 13.6% when compared to the control, the Fchlo-a parameters did not show damages to the PSII reaction centers. Although the heat treatment affected germinability, germination percentages were higher than 70% even at the highest temperatures. The absence of stress indicators to the heat treatment suggests the tolerance of the seeds to high temperatures.