Water relations of seed development and germination in muskmelon (Cucumis melo L.). VII. Influence of after-ripening and ageing on germination responses to temperature and water potential.
Welbaum, G.; Bradford, K. J.;
Journal of Experimental Botany Year: 1991 Vol: 42 Issue: 242 Pages: 1137-1145 Ref: 23 ref.
1991
บทคัดย่อ
The effects of storage conditions on the germination of developing muskmelon cv. Top Mark seeds were tested to determine whether after-ripening is required to obtain maximum seed vigour. Seeds were harvested at 5-day intervals from 35 (immature) to 60 (fully mature) days after anthesis (DAA), washed, dried and stored at water contents of 3.3 to 19% (DW basis) at 6, 20 or 30 deg C for up to 1 year. Germination was tested in water and in polyethylene glycol 8000 solutions (-0.2 to -1.2 MPa osmotic potential) at 15, 20, 25 or 30 deg . Germination percentages and rates (inverse of mean times to radicle emergence) were compared with those of newly harvested, washed and dried seeds. For seeds harvested at 40 and 60 DAA, 1 year of storage at less than or equal to 20 deg and water contents <6.5% significantly increased germination percentages and rates at 20 deg but had little effect on germination at 25 and 30 deg . Storage reduced the estimated base temperature (Tb) and mean base water potential ( psib) for germination of both 40 and 60 DAA seeds by approximately 5 deg and 0.3 MPa, respectively. Immature seeds harvested 35 DAA showed the greatest benefit from storage at 3 to 5% water content and 30 deg , as germination percentages and rates increased at all water potentials ( psi ). Storage under these conditions had little effect on the germination of mature seeds in water but increased germination percentages and rates at reduced psi 's. Accelerated aging for 1 month at 30 deg and water contents from 15 to 19% increased germination rates and percentages of mature seeds at reduced psi 's but longer durations resulted in sharp declines in both parameters. Immature seeds lost viability within 1 month under accelerated aging conditions. An after-ripening period is required at all stages of muskmelon seed development to expand the temperature and water potential ranges allowing germination and to achieve maximum germinability and vigour. Postharvest dormancy is deepest at the point of maximum seed DW accumulation and declines thereafter, both in situ within the ripening fruit and during dry storage.