Physiological characteristics of photosynthesis in Iris lactea Pall. var. chinensis (Fisch.) Koidz grown in salt and alkali soil Relationship Between the Leaf Tissue Characteristic and Drought Resistance of Iris lactea Pall. var. chinensis(Fisch.) Technological System of Tissue Culture and Rapid Propagation of Iris lactea Pall. var. chinensis(Fisch.) Koidz.