Study On Tolerant Ability Of Four Species Of Iris L. Under NaCl Stress

In potted plant experiment, physiological responses (growth, physiological and biochemical indicators) to soil NaCl stress(0.1%,0.2%,0.3%,0.4%,0.5%,0.6%,0.7%,0.8%,0.9%,1.0%) were studied in four species of Iris L.: Iris lactea var. chinensis, Iris germanica, Iris pseudacorus, Iris ensata var. hortensis, and appraised the comprehensive salt tolerant ability of these species. The main results were described as follows:1. With NaCl stress concentrationsss increased, the leaves of four species of Iris L. were becoming dry, yellow, missing green and growth potential recession in different degrees. Under high concentrationssss of salt stress, the survival rates of four species decreased except for Iris lactea var. chinensis.2. The relative water content and souble protein content of four species was a continuous downward trend with the stress concentrationsss and time. The membrane permeability, MDA, free proline content and SOD activity of four species showed a continuous upward trend with stress concentrationsss and time. The chlorophyll content and root activity of Iris germanica, Iris pseudacorus and I. ensata var. hortensis decreased with the stress time, and Iris lactea var. chinensis increased after the first drop trend with the stress concentrationsss.3. The comprehensive salt tolerant ability of four species was analyzed by subordinate function. The result was that the rank of salt tolerant ability of four species was Iris lactea var. chinensis> I. ensata var. hortensis> Iris germanica> Iris pseudacorus.4. Through the apparent characteristics of the observation and the analysis of physiological indicators, coming to the result that the tolerant and survival threshold of Iris lactea var. chinensis is above 1.0%, the resistant threshold is 0.5%; the tolerant and survival threshold of Iris germanica is 0.5%and 0.7%, the resistant threshold is 0.1%; the tolerant and survival threshold of Iris pseudacorus is 0.5% and 0.7% ; the tolerant and survival threshold of I. ensata var. hortensis is 0.6%and 0.8%, the resistant threshold is 0.2%.