EFFECTS OF GROWTH TEMPERATURE AND WINTER DURATION ON LEAF PHENOLOGY OF ERYTHRONIUM-JAPONICUM, A FOREST SPRING GEOPHYTE

The effects of growth temperature and winter duration on the leaf phen ology of Erythronium japonicum were examined in two experiments. Bulbs wintered in the field were cultivated at 10 and 20-degrees-C and the bulbs were cultivated at 15-degrees-C after chilling treatment at 3-de grees-C for 60 and 120 days and without chilling in winter. The plants cultivated at 20-degrees-C showed significantly earlier leaf emergenc e, a more rapid rate of leaf extension and shorter leaf longevity than those cultivated at 10-degrees-C. The decrease in the leaf longevity at 20-degrees-C resulted from the decreases in the durations of all of the developmental, mature, and senescent phases. The bulbs without ch illing treatment did not sprout leaves and those with chilling treatme nt sprouted leaves. The increase in the length of chilling treatment f rom 60 to 120 days affected leaf phenology in same manner as the incre ase in the growth temperature from 10 to 20-degrees-C.