Germination of papaya seed in response to desiccation, exposure to subzero temperatures, and gibberellic acid

Abstract

The effects on germination of two lots of Carica papaya seed of dehydration at 25 °C, followed by exposure to -20 °C or -196 °C, were evaluated with and without gibberellic acid (GA3) treatment. In the absence of GA3 treatment, dehydration increased subsequent germination only in seed lot 1 when moisture content (m.c.) was reduced from 59% to 6.0% and 5.3%. In seed lot 2, dehydration followed by exposure to -196 °C increased germination compared with dehydration alone. Treatment with GA3 enhanced germination rate in all treatments. Dehydration to 5.3% (lot 1) or 6.9% and 6.8 % m.c. (lot 2), followed by exposure to subzero temperatures and treatment with GA3, were the most favorable combined treatments to enhance papaya seed germination. The results suggest that papaya seed presents an orthodox behavior, permitting germplasm conservation in conventional and cryogenic genebanks.