International Journal of Ecology and Environmental Sciences 27:
23-29, 2001
© International Scientific Publications, New Delhi
Effect of Temperature, Salinity and Burial on Seed Germination and Seedling
Emergence of Five Coastal Sand Dune Legumes
A.B. Arun, N.S. Raviraja and K.R. Sridhar
ABSTRACT
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 28C in distilled water and 25% seawater
at 2 cm sand burial. The upper limit of seed germination was 42C in freshwater; 50%
seawater; 10 cm burial with freshwater and 5 cm burial with seawater at 28C. The upper
limits of recovery of germination was 42C, 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 (42C) 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.
Key Words: Abiotic factors,. Coastal dunes, Dune stabilization, Mat-forming
creepers, Nitrogen fixation, Seed decay, Seed dormancy, Strand vegetation, Tree legumes,
Tropics.