Viability of onion (Allium cega) seed as influenced by temperature during seed growth

Abstract

SUMMARYThe yield and performance of seeds from crops of winter‐hardy, bolting‐resistant onion grown at temperatures of 15–16, 18–19 and 22–23°C in 1979, 1980 and 1982 were compared.Yields of seed from crops grown at 22–23°C were lower than those from crops grown at lower temperatures but the seeds ripened between 11 and 32 days earlier. Seeds from crops grown at mean temperatures of above 18°C gave higher percentage germination when imbibed at 30°C than 20°C and they also gave higher percentage seedling emergence than those from crops grown at lower temperatures. Seedlings from seeds produced at mean temperatures above 18°C were heavier than those from seeds of a similar weight but produced at lower temperatures. None of these differences were associated with differences in seed weight, embryo weight or seed dormancy but were positively correlated with differences in seed N‐concentration. The differences were also associated with the rate of imbibition of water as high germination, high N‐content seeds had a slower rate of imbibition than low germination, low N‐content seeds of the same weight.