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 degree C (98 to 100) and low at 45 degree C (only 8). Low concentration of either NaCl or Na sub(2)SO sub(4) up to 0 multiplied by 01 M had no effect, except that Na sub(2)SO sub(4) was effective in stimulating germination at 45 degree C. Seed germination tolerance to high salt concentration (0 multiplied by 1 and 0 multiplied by 2 M) was temperature-dependent, and more tolerance occurred at 25 degree and 35 degree C and less at 15 degree and 45 degree C. Sulphuric acid was more effective in breaking seed coat dormancy than methanol, boiling water or incision of the testa.