Responses Of Six Iris Species To Drought Stress

In the aspects of external morphology, leaf anatomical structure, physiological and biochemical indicators, the responses to drought stress were studied in six species of Iris L.: I. tectorum, I. germanica, I. lactea var. chinensis, I. pseudacorus,I. sanguinea, I. ensata var. hortensis. This paper found out that:1.From drought index and soil water content of three critical states (normal growth, temporary wilting and permanent wilting), it was found out that the drought resistant ability was I. germanica, I. tectorum, I. lactea var. chinensis, I. ensata var. hortensisi, I. pseudacorus, I. sanguinea. But after rehydration (I.germanica without rehydration), the whole germination rate was I. tectorum, I. pseudacorus, I. ensata var. hortensis, I. lactea var. chinensis.2.Leaf anatomical structure of I. germanica and I. lactea var. chinensis showed their great adaptability to drought; next were I. pseudacorus and I. sanguinea; I. tectorum and I. ensata var. hortensis showed relatively weaker adaptability to drought.3.With the prolongation of drought stress, the relative water saturation deficit, conductivity, MDA, the relative content of anthocyanins, soluble sugar content and proline content rose; the soluble protein generally rose first, fell later, and then rose again; the change of total chlorophyll and total SOD activity were more complicated.4.Through principal component analysis, it was found out that the soluble sugar content, leaf relative water saturation deficit, praline content, SOD activity , the total relative content of anthocyanins were closely related to the drought resistant of six Iris species.5.Through analyzing subordinate function, it was concluded that the comprehe- nsive drought resistant ability of six Iris species was I. germanica>I. tectorum>I. lactea var. chinensis>I. ensata var. hortensis>I. pseudacorus>I.sanguinea. Through cluster analysis, six Iris species could be divided into 4 categories: I. germanica and I. tectorum had strong drought resistance; I. lactea var. chinensis had lesser strong drought resistance; I. ensata var. hortensis had ordinary drought resistance; I. pseu- dacorus and I. sanguinea had weak drought resistance.