STANDARDIZATION OF VARIABLES FOR ACCELERATED AGING OF PAPAYA SEEDS

Seed germination in papaya is affected by many environmental factors including temperature. The germination of papaya seeds is frequently reported to be slow, erratic and low. An effort was attempted to define the variables for accelerated aging test in papaya. The effect of accelerated aging on seed quality of papaya was also studied. To observe the optimum time for accelerated aging test, the seeds were aged at 40±1 and 45±1°C for different time intervals. Seeds from both fresh and aged seed lots were used to conduct standard germination test (%). No germination was observed in accelerated aged seeds at 45±1°C for 24, 48, 72, and 96 h and at 40±1°C in time intervals of 72 and 96 h. The standard germination was significantly higher in freshly extracted seeds (67.14%) followed by 24 and 48 h accelerated aged seeds registering 30.96 and 14.89% respectively. Significantly higher seedling length and dry weight were observed in seedlings of fresh seeds followed by seedlings of 24 h aged seeds and 48 h aged seeds. Vigour index-I decreased in papaya seed lots with increase of aging time. Maximum vigour index-I was observed in fresh seeds. Amongst the aging times, 24 h aged seeds recorded significantly higher vigour index-I. Among different aging time, vigour index-II was observed to be significantly higher in fresh seeds followed by 24 h aged seeds. Fresh seeds recorded significantly higher viability percentage (74.85%) than 24 h aged (37.16%) and 48 h aged seeds (20.21%). Electrical conductivity values showed significant differences in different aging time and it was maximum in 48 h accelerated aged seeds. Further, the dehydrogenase activity decreased with increase in aging time. The variable for accelerated aging were standardized to be 40±1°C for 24 h. All the seed lots showed decline in most of seed quality parameters when they were accelerated aged at 40±1°C, for 24 and 48 h.