Desiccation induced loss of vigour and viability during storage in neem (Azadirachta indica A. Juss) seeds

The response of viability and vigour to desiccation and storage period was examined in neem seeds at ambient conditions. Freshly harvested neem seeds maintained 100% germination up to 15 days after harvest (dah), although mas sive loss (70%) in moisture content from 40.3% (zero dah) to 11.8% (15dah) was recorded. Further desiccation of seeds below lowest safe moisture conte nt (LSMC) (11.8%) resulted in substantial loss in viability. Complete loss of viability was recorded at 180dah (5.9% moisture content) of storage. How ever, the vigour index was maintained only up to four dah of storage when t he moisture content was 29.5%. Desiccation of seeds to 25.6% moisture conte nt on six dah resulted in significant loss in GI (75%), whereas there was a marginal loss in SVI (20%), TZ-embryonic axes (4%) and TZ-cotyledon (12%). Further dehydration of seeds to 14.4% and 11.8% moisture content on 12dah and 15dah respectively showed substantial loss in seed vigour, although the se seeds still exhibited 100% germination. Our results suggest that the nee m seeds are desiccation-tolerant to intermediate moisture content (11.8%), but once dehydrated below it exhibits desiccation-sensitivity, thus can be categorized under intermediate storage behaviour. Significant role of dryin g in loss of viability and vigour has been discussed to establish the inter mediate storage physiology of neem seeds.