SEED DORMANCY IN GERMPLASM COLLECTION OF RICE (ORYZA-SATIVA) INSENSITIVE TO PHOTOPERIOD

Field evaluation of 212 photoperiod-insensitive germplasm collection o f rice (Oryza sativa L.) during autumn seasons of 1990 and 1991 reveal ed that 155 collections had no seed dormancy. The seed dormancy in 57 collections ranged from 7 to 30 days. ''Cheni Ahu' showed the highest dormancy period (30 days), followed by 'As 326', 'Goalbhog', 'Banglami ' and 'Bala'. In 21 indigenous collections it was observed both under field and laboratory conditions. 'Cheni Ahu', 'Goalbhog', 'Nilajee', ' Banglami', 'As 229', 'As 93-1', 'Guni Ahu', 'Rongadoria 4', 'Basmati C ulture' and 'Podumani Ahu' were identified promising donors for seed d ormancy. Correlation study showed significant positive correlation wit h plant height and lodging score. Field as well as laboratory methods were found necessary for identification of dormant rice germplasm coll ections. Seed dormancy of the indigenous germplasm collections appears to be an adaptive mechanism for their survival in the hot, humid rain y season.