Physiological tolerance and sensitivity to water defecit in potatoes cultivars

In this study, the effect of water defecit on the physiological characteristics of ten potato cultivars at vegetative growth stage under greenhouse conditions was investigated at collage of agriculture of Isfahan University of Technology, Iran in 2016. Treatments included two irrigation regimes of 30 and 80% depletion of soil available water. Water stress decreased quantum efficiency of photosystem II, rate of photosynthesis, stomatal conductance, stomatal transpiration, water use efficiency, chlorophyll a, chlorophyll b, total chlorophyll, carotenoids and plant dry weight but increased carbon dioxide concentration in the cavity below the hole, chlorophyll a/b ratio, chlorophyll/ carotenoids ratio. Significant difference existed among potato cultivars in terms of most measuered traits. The interaction effects of irrigation regime and cultivar were significant on rate of photosynthesis, carbon dioxide concentration in the cavity below the hole, stomatal conductance, chlorophyll a, chlorophyll a/b ratio, chlorophyll / carotenoids ratio and plant dry weight. Under both irrigation regimes the highest amount of plant dry weight was achived for Marfona and Satina and the lowest weight was obtained for Bourn cultivar. Maximum reduction in plant dry weight under water stress treatment belong to Bourn (77%) and Spirit (76%) and minimum reduction (35%) was obtained in Santa. In this experiment, based on stress torence index (STI), cultivars Agria, Santia, Marfona, Spirit and Sante compared to the other potato cultivars, were more tolerant to water stress that was imposed during vegetative stage of plants