Seed dormancy alleviation of Grewia tenax (Forssk.): A wild fruit tree species of Pakistan

Grewia tenax (forssk.) fiori is a fruit shrub and grows wild in arid and semi-arid tropics of asia and africa. the species is highly valuable for the rural populations because of its edible fruit and fodder for livestock. species has immense potential for re-vegetation of degraded lands,as it has ability to withstand soil salinity and drought. wild stands of the species are sparse which is supposed to have some kind of seed dormancy. seeds of g. tenax were subjected to different combinations of heat and cold seed stratification treatments in two consecutive experiments. a positive correlation (r2 = 0.97) was observed between total emergence and weeks of seed exposure to constant dry heat at 40°c from 0 to 4 weeks. maximum germination (70%) was achieved,when seeds were exposed to dry heat at 40°c for 4 weeks as compared to control (20%). seeds exposed to constant heat for 4 weeks also took only 4 and 5 days to reach 1st and 50% emergence,respectively as compared to untreated seeds,which took 10 and 14 days to reach 1st and 50% emergence,respectively. moreover,emergence spread lasted only 4 days as compared to untreated seeds with 21 days. our results indicate that seeds of g. tenax possess a limited physiological dormancy which can be overcome by heat stratification © 2015,pakistan botanical society. all rights reserved.