PHYTOCHROME-MEDIATED GERMINATION CONTROL OF HYGROPHILA-AURICULATA SEEDS FOLLOWING DRY STORAGE AUGMENTED BY TEMPERATURE PULSE, HORMONES, ANAEROBIOSIS OR OSMOTICUM IMBIBITION

A pulse of red light (R) stimulates, and far-red light (FR) inhibits g ermination of Hygrophila auriculata seeds with primary dormancy. These seeds lose their light requirement for germination after 4 months of dry storage in air. A secondary dormancy can then be induced by 5-day dark inhibition in osmoticum in air (21% O2). Red light will break thi s dormancy. Seeds stored in nitrogen gas (0% O2) neither lose the ligh t requirement, nor is a secondary dormancy imposed. However, FR stimul ated some germination in osmoticum-induced dormant seeds is evident wh en such seeds are given a 1-6 hr 40-degrees-C pulse, gibberellin A3 (G A3), or ethylene treatments. These results suggest that changes of pho tosensitivity from a low fluence response to a very low fluence respon se may occur concurrently with the status of dormancy in seeds. The pr ocesses of dry after-ripening, the induction of secondary dormancy or of photosensitivity all require oxygen.