Effect of temperature, salinity and burial on seed germination and seedling emergence of five coastal sand dune legumes

Greenhouse studies were conducted to determine the effects of temperature, salinity and sand burial on seed germination, seedling emergence and recovery of five common sand dune legumes (Canavalia cathartica, Canavalia rosea, Crotalaria retusa, Crotalaria verrucosa and Pongamia pinnata) of the west coast of India. Mean seed germination was highest in most plant species at 28°C in distilled water and 25% seawater at 2 cm sand burial. The upper limit of seed germination was 42°C in freshwater; 50% seawater; 10 cm burial with freshwater and 5 cm burial with seawater at 28°C. The upper limits of recovery of germination was 42°C, 100% seawater and 10 cm burial. Burial of seeds at 2 and 5 cm resulted in elevated levels of seedling emergence. Seed decay was considerably reduced in seawater in all plant species except Pongamia pinnata. The high induced dormancy at higher temperature (42°C) and salinity (100% seawater) and deep burial (10 cm) might result in the establishment of seed bank. Two major human interferences (removal of plant debris and construction of granite wall to prevent erosion) on the accumulation of organic debris on the sand dunes might adversely affect seed germination and ultimately the plant community structure.