Abstract: Taking drought-sensitive wheat cultivar Wangshuibai and drought-tolerance cultivar Luohan 7 as test materials, a hydroponic experiment was conducted to study the effects of drought stress on  root system morphology,  physiological characteristics and leaf photosynthesis of wheat seedlings, aimed to elucidate the adaptation mechanisms  to drought stress. Under drought stress, the root vitality of the cultivars increased markedly, but the root number and root surface area decreased. Drought stress decreased  relative water content and increased the
ratio of bound water to  free water
in leaves of  Wangshuibai, but had less effects on Luohan 7.  Drought stress decreased, the leaf chlorophyll content, Pn, gs, Ci, and transpiration rate of the two cultivars, but had no significant effects on
 leaf chlorophyll content and Pn of Luohan 7. Drought stress decreased the leaf area of the two cultivars and the root biomass, shoot biomass, and plant biomass of Wangshuibai, but had no significant effects on Luohan 7. The results indicated that under drought stress, drought-tolerant wheat cultivar was able to compensate  decreased root  absorption area and retain  higher root water uptake capability via enhancing  root vitality and maintaining higher root biomass, and further, to keep  higher leaf photosynthetic area and Pn to mitigate the inhibition  of drought on wheat seedlings growth.

Key words: wheat, drought stress, drought tolerance, photosynthesis, root system