Identification And Assessment On Drought Resistance Of Germplasm Resources Of Iris Lactea Pall.var.chinensis (Fisch.) At Seedling Stage

The drought resistance of 15 germplasm resources of Iris lactea Pall. var. chinensis (Fisch.) at seedling stage was comprehensively identified and evaluated using the simulating drought stress and rewatering method in green house. The morphological and physiological indexes were measured and analyzed. The results showed that: As the stress of drought was intensified, the relative water content of leaves, the content of chlorophyll and the relative growth rate of plant were decreased; Meanwhile, the relative electrical conductivity rate, the content of MDA and the free proline accumulation were increased. After rewatering, the values of measured indexes were recovered at the different degrees.With cluster analysis, 15 germplasm of I. lactea were divided into three grades of the drought resistance, e.g. the stronger drought resistant germplasm including ML008,ML007,ML015,ML009 and ML006; the medium drought resistant germplasm including ML014,ML012,ML 011,ML 013,ML 010,ML 005,ML 004 and ML 003; and the weaker drought resistant germpalsm including ML002 and ML001. Meanwhile, the Pearson correlation analysis among the physiological indexes was conducted, and the results showed that the physiological indexes were significantly correlated with each other (p<0.01).Tissue parameters of leaves of 4 germplasm of Iris lactea were observed and analyzed to study the relationship between the leaf tissue parameters and drought resistance of Iris lactea Pall. var. chinensis (Fisch.). The results showed that there were the relationship of leaf thickness, upper and lower epidermis thickness, cutin thickness, stoma density, stockade tissue thickness, sponge tissue thickness, CTR, SR and ratio of stockade tissue thickness sponge tissue thickness among the germplasm. The the stronger drought resistant germplasm were with high stoma density, thick stockade tissue, high CTR, low SR , high ratio of stockade tissue thickness sponge tissue thickness and small size of upper epidermis cells in leaves had strong ability of drought resistance. The weaker drought resistant germpalsm were with low stoma density, thin stockade tissue, low CTR, high SR , low ratio of stockade tissue thickness sponge tissue thickness and big size of upper epidermis cells in leaves had weaker ability of drought resistance.