Seed biology imperative for conservation and restoration of Swertia thomsonii C.B. Clarke-an endemic medicinal plant of Himalaya.

Endemic medicinal plants deserve immediate research priorities as they typically show a limited distribution range, represent few and fragmented populations in the wild and are currently facing anthropogenic threats like overharvesting and habitat degradation. One of the important aspects of ensuring their successful conservation and sustainable utilization lies in comprehending the fundamental seed biology, particularly the dormancy status and seed germination requirements of these plants. Here, we studied the seed eco-physiology and regeneration potential of Swertia thomsonii-an endemic medicinal plant of western Himalaya. We investigated the effect of different pre-sowing treatments, sowing media and sowing depth on seed germination parameters of S. thomsonii. Seeds of S. thomsonii exhibit morphophysiological dormancy (MPD), i.e. when the embryo of the seed is morphologically and/or physiologically immature. Wet stratification at 4 °C for 20 days, pre-sowing treatment with 50 ppm GA and pre-sowing treatment with 50 ppm KNO were found ideal for overcoming dormancy and enhancing the seed germination of S. thomsonii. Furthermore, seed germination and seedling survival were significantly influenced by pre-sowing treatments, sowing media and sowing depth. The percentage of seed germination and seedling survival got enhanced up to 84-86% and 73-75% respectively when seeds were pre-treated with GA or KNO and then sown in cocopeat + perlite (1:1) at a depth of 1 cm. The information obtained in the present study outlines an efficient protocol for large-scale cultivation of S. thomsonii thereby limiting the pressure of overexploitation from its natural habitats and may also help in the restoration and conservation of this valuable plant species.