Seed longevity, germination and seedling vigour of Rheum australe D. Don: A step towards conservation and cultivation

- The species is in high demand, has endangered status and required conservation interventions.
- Freshly harvested seeds exhibited high viability (94%) and germination (82%).
- Storage of seeds beyond 24 months resulted in significant decline in seed quality and vigour.
- The seed pretreatments (GA3, KNO3 and chilling) neither affected significantly the final germination of fresh seeds (86, 80 and 78%, respectively) nor differentially stored seeds.
- Seed longevity (time taken for 50% decline in seed viability) was about 45 months, 60 months storage resulted in complete loss of viability.

A 60 months study was carried out to assess the seed longevity and effect of duration of storage period on viability, germination and seedling vigour in Rheum australe D. Don. (rubarb), a highly valued medicinal herb. The species is in high demand and has endangered status therefore, required conservation/cultivation interventions. The study was carried out using seeds of same lot after storage of every six months (0, 6, 12, 18 and so on) till complete loss of seed viability. Freshly harvested seeds exhibited high seed viability (94%) and were non-dormant; above 80% germination occurred within a week. The above status was completely retained till 12 months storage. Beyond this period both seed viability and germination declined consistently with the progression of storage period. A complete loss of viability was observed beyond 60 months storage. Seed pre-treatments tested namely, GA3, KNO3 and chilling neither affected significantly the final germination of fresh seeds (86, 80 and 78%, respectively) nor differentially stored seeds. However, GA3 (1 mM) and chilling significantly reduced the time required for germination. The seed longevity (time taken for 50% decline in seed viability) of R. australe was about 45 months, but a storage period of no longer than 24 months can be recommended. During 24 months storage period the seed viability and germination were reasonably high and resulted in the production of healthy seedlings with high survival rate. The outcome was favourable for the conservation/cultivation of the species.

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