Comparative ecophysiology of seed germination in two pairs of closely related pines of mediterranean and himalayan origins

In this study we have examined the comparative ecophysiology of seed germination in two pairs of related pines of Mediterranean and Himalayan origins. One pair comprises Pinus canariensis and Pinus roxburghii, and the second Pinus peuce and Pinus wallichiana. Each pair has close taxonomic and morphological affinities. We have observed considerable differences among these pines about their germination behaviour. Seed germination of Pinus canariensis was feasible within a range of 15-20°C both under light and darkness, while the optimum germination of Pinus roxburghii was achievable at 25°C under white light. Germination rate of Pinus roxburghii was significantly enhanced under white light. A brief red light pulse resulted in promoting germination in Pinus roxburghii; however, the enhancing effect of red light was reversed by a brief far-red pulse; which indicated the mediation of phytochrome system in seed germination. Pinus peuce seeds were deeply dormant and required an extended period of stratification in order to come out of dormancy. Pinus wallichiana seeds were less dormant as compared to Pinus peuce, 30 d stratification or incubation under white light resulted in overcoming the dormancy.