Harvesting seeds before dormancy induction in Hyoscyamus niger, a threatened medicinal herb of trans Himalaya: implication for propagation without seed pre-treatments

Hyoscyamus niger L., an endangered plant of cold desert region of trans-Himalaya has long been utilized for medicinal purposes due to presence of significant quantity of analgesic and psychoactive molecules. The species multiply only through seeds and the latter reported to exhibit dormancy. Seed pre-treatments: sodium nitrate, potassium nitrate, sodium azide, sodium nitroprusside, cold stratification and gibberellic acid proved effective to initiate germination and caused 34, 42, 62, 68, 88 and 96% germination respectively. Interestingly, at certain stage of plant growth, H. niger contains all stages of seed development: flowering stage (apical region) to complete matured seeds (basal region). Therefore, dormancy/germination status of seeds from same twig having variable maturity was compared. Quite remarkably, they exhibited a very interesting pattern; a reciprocal relationship between seed maturity (or seed weight) and dormancy was observed. Fully matured seeds exhibited complete dormancy and in contrast, the comparatively immature seeds germinated well (92%). The findings are novel and have been reported first time as far as seeds of H. niger is concerned. The data have practical implications and can be easily manipulated for the propagation of species without seed pre-treatments.