Department of Botany, College of Science, King Saud University, P.O. Box 2455. Riyadh 11451. Saudi Arabia
ABSTRACT
Cassia senna L. is adapted to the dry climate of Saudi Arabia, and temperature and salinity are major factors that influence its seed germination.
Seed germination percentage for the control was high at 15, 25, 35 and 40°C (98 to 100)
and low at 45°C (only 8). Low concentration of either NaCl or Na2 SO4 up to 0.01 M had no effect, except that Na2 SO4 was effective in stimulating germination at 45°C. Seed germination tolerance to high salt concentration (0.1 and 0.2 M) was temperature-dependent, and more tolerance occurred at 25° and 35°C and less at 15° and 45°C.
Sulphuric acid was more effective in breaking seed coat dormancy than methanol, boiling
water or incision of the testa.