Some effects of drying leek (Allium porrumL.) seeds harvested at different stages of maturity on seed and seedling performance

Abstract

SummaryIn three experiments, the time when 50% of moisture had been lost from leek seed heads, harvested at different stages of growth, decreased with an increase in the vapour pressure deficit (D) of the drying air from 27 days at 0.5 kPa to 1.6 days at 5.0 kPa and, except at the slowest drying rates, was unaffected by harvest date. Equilibrium moisture contents of the seed heads, which corresponded approximately with the stage when seeds could be readily threshed from the capsules, occurred 78 days after harvest at 0.5 kPa and 14 days after harvest at 5.0 kPa. The time to reach equilibrium seed moisture content declined with an increase in D from 79 days at 0.5 kPa to 17.5 days at 5.0 kPa, with immature seeds (harvested 40–50 days after flowering (DAF)) taking longer to dry than more mature seeds (harvested 72–78 DAF) because of their higher initial moisture content. Drying seed heads at 40°C (D, 3.0 kPa) reduced germination substantially compared with that at 30°C (D, 3.0 kPa) particularly for immature...