Ex-Situ Seed Storage Behavior ofDipcadi saxorumBlatter, an Endangered Species from India

Abstract

A large number of seeds exhibiting intermediate and recalcitrant storage physiology, generally found in the tropics, subtropics, aquatic, and riparian environments, pose difficulty in ex-situ conservation because of their inherent intolerance to desiccation. The rapid drying of such seeds, especially intermediate seeds, renders them tolerant to desiccation to sufficiently low moisture content suitable for ex-situ conservation. The aim of this work was to establish the seed-storage physiology of Dipcadi saxorum, an endangered plant species of India, and develop suitable ex-situ storage protocol for conservation. Ex-situ storage potential of short-lived (4 months) seeds of D. saxorum was extended to 18 months by storage at 15°C after rapid drying of freshly harvested seeds to low (4%) moisture content (MC). Seeds exhibited 99-100% viability during storage under ambient conditions (slow-drying) up to 50 d (8.9% MC) but storage for 70 d resulted in 78% germination (6.5% MC). Seeds became nonviable after 170 d of storage (registering 5.1% MC) under ambient conditions. In contrast, the rapid-drying using silica gel reduced the MC from 42.42 to 4.5% within 9 h and showed 100% germination. The storage potential of rapidly dried (4, 9, 15 and 30% MC) seeds (tested at 25, 15, and -20°) Ex-Situ Seed Storage Behavior of Dipcadi saxorum 283 increased to 18 months; seeds rapidly dried to 4% MC at 15°C gave 25% germination. Electrolyte leakage loss was reduced in the rapidly dried seeds compared with slow-dried seeds and negatively correlated (ranging from R 2 = -0.97 to -0.99) with the percentage germination. Compared with slow drying, the rapid drying of seeds to 4 and 9% MC improved significantly the storage potential of D. saxorum seeds at all the storage temperatures studied. Our study revealed that seeds of D. saxorum exhibited intermediate storage physiology and can be desiccated to sufficiently low moisture content (4%) well suited for ex-situ storage for conservation, if rapidly dried despite their sensitivity to desiccation.