Storage-Dependent Changes in Dormancy and Germination of Himalayan Mayapple (Podophyllum hexandrum Royle) Seeds and their Response to Gibberellic Acid

Abstract

The storage-dependent changes in viability and dormancy/germination status of seeds of a Western population of Himalayan Mayapple (Podophyllum hexandrum), an endangered plant species of high medicinal value, have been monitored with particular reference to the changes in seed responsiveness to GA3. Shortly after harvest (3 months), seeds exhibited dormancy that was marginally overcome after storage for 30 months. GA3 treatment was effective in overcoming the dormancy, particularly when concentrated H2SO4 was used. The responsiveness of the seeds to GA3, however, decreased with the storage period. A subset of seeds that failed to germinate under a GA3-H2SO4-GA3 treatment eventually deteriorated. GA3-induced enhancement of the activities of α-amylase and dehydrogenases (2,3,5 triphenyltetrazolium chloride (TTC) reduction) corresponded to germination improvement in seeds stored for a short duration, but not in seeds stored for long period of time. Lipid peroxidation in seeds did not change owing to storage or GA3 treatment, whereas catalase activity tended to decline marginally. Seed phenolic contents were not involved in the seed germination behavior. Possible mechanisms of heterogeneity in responsiveness of seeds to GA3 are discussed.