Seedlings Of Three Caragana In Response To Water Stress

Caragana acanthophylla, C. leucophloea and C. korshinskii are perennial deciduous shrub of Leguminosae Caragana. This paper studied the change of morphological characteristics, biomass and physiological indicators. Investigated compared their drought tolerance. The conclusions were as follows:(1) Water stress had significantly effected on the growing conditions of the seedlings. With the decrease of water supply, the height, basial diameter and leaf number of seedlings were reduced. And the changed of degree of height and leaf number were more than it of root. C. korshinskii and C. leucophloea focused on the growth of height, but C. acanthophylla focused on the growth of basial diameter.(2) Water stress had significantly effected on the biomass and distribution. With the decreasing of water supply, the accumulation of biomass reduced. The total biomass of C. acanthophylla and C. leucophloea under severe drought conditions were half of under nomal water conditions. C. korshinskii under severe drought conditions was one third of nomal water. Under water stress conditions, seedlings all have distributed more biomass to root system. Therefore, the root to shoot ratio were increased but the photosynthesis biomass ratio and the number of lateral root were stabilization with the increasing of water stress. C. acanthophylla and C. leucophloea distributed more biomass to root than C. korshinskii, so the root to shoot ratio of it was more than C. korshinskii.(3) Proline accumulation of seedlings under water stress and the change of soluble sugars and malondiadehyde were same as proline. But water content in leaf and chlorophyll content were decreased with increasing of water stress.As for C. acanthophylla, the highest of proline were observed under severe drought was twice under nomal water. But solube sugar wasn't accumulated under water stress. The malondiadehyde content under severe drought was twice under nomal water. Under the drought and severe drought conditions, chlorophyll content of C. acanthophylla was one third of under nomal water. Therefor, the ability of anti-peroxidation and descreasing the membrane damage was not good.As for C. leucophloe, the ability of anti-peroxidation and descreasing the membrane damage was good. The highest content of proline which was observed under drought conditions was four times under nomal water conditions. And soluble sugars were accumulated under severe drought conditions. So that it can keep low malondiadehyde content and high chlorophyll content. This showed that the drought tolerance of C. leucophloe was good.As for C. korshinskii, the highest content of proline which was observed under drought conditions was twice under nomal water conditions. Chlorophyll content of it was reduced significantly but malondiadehyde wasn't accumulated under water stress. This showed that C. korshinskii have good physiological adjustment to water stress.(4) Analysis by fuzzy membership functions, it showed that their drought resistance descending order was as following: C. leucophloe > C. korshinskii > C. acanthophylla.