Plant Tissue Culture for 8 Pagoda Tree Var ieties of Papilionoideae and Effects of Genotypes on Regeneration Ability EFFECT OF SALT STRESS ON PHOTOSYNTHESIS AND GROWTH OF FOUR TREE SPECIES SEEDLINGS Comparison Study on Photosynthesis of Pagoda Tree and Walnut Seedlings under Salinity Plant Tissue Culture for 8 Pagoda Tree Var ieties of Papilionoideae and Effects of Genotypes on Regeneration Ability