Study On Salt Tolerance In Stage Of Seed Germination And Seeding Of Stylosanthes Guianensis Pasture Plant

In this study 12 varieties of stylo seeds or seedlings were treated with NaCl during the germination period or the seedling period, the biological indices, their physiological and biochemical indices of salt-tolerancewere comprehensively analyzed and identified by the interrelated analysis law of grey system. Results showed that:1 Effects of salt stress to biological indices of different varieties of stylo seeds or seedlings1.1 During the germination period stylo seeds were treated with different concentration of NaCl (0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6% --quality percentage of water). The seed germination rates decreased with the increasing of NaCl concentration. However, low salt concentration treatments increased seed germination rates for some varieties of stylo seeds. Stylo seeds were treated with more than 1.0% salt concentration, Stylosanthes guianensis GC1463 showed strongest salt tolerance.1.2 The growth of hypocotyls and cotyledons of stylo seeds was greatly inhibited with the increasing of salt concentration; the length of hypocotyls and cotyledons against salt concentration was significantly negative relation under the salt stress. However, the treatment of low salt of NaCl stimulated the growth of hypocotyls and cotyledons of some specific variety.1.3 Seedlings were planted in soils with different salt concentration (0%, 0.2%, 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%- quality percentage of soil). The Wilting degrees of leaves of stylo seedlings were intensified and the wilting speeds of leaves of stylo seedlings increased with the increasing of salt concentration. But the restrained degrees of salt stress on leaves of different stylo varieties were different. With the increasing of treatment concentration, the growth of stylo seedlings were partially inhibited or completely inhibited; and the height decreased significantly comparing with controls; and the biomasses (the above ground biomass and sub ground biomass) of stylo seedlings were distinguished with the controls.2 Effects of salt stress on physiological and biological indices of stylo seedlings2.1 With the increasing of salt concentration, the results showed that membrane permeability, Na+, and Cl-contents increased significantly and the chlorophyll contents of stylo seedlings decreased under salt stress; the increases in the Na+ contents of stylo seeding was more than those of Cl- contents of stylo seeding under salt stress, the ratio of Na+ / Cl- of stylo seedlings decreased. Results revealed that great differences existed among the physiological and biological indices of different varieties of stylo seedlings under salt...