Evaluation of water use efficiency of three varieties of apple rootstocks under long term moderate drought stress
In order to evaluate the water use efficiency of different varieties of apple rootstocks under drought stress and explore the physiological mechanisms causing the differences,this experiment used one-year-old malus hupehensis as the base stock and selected three varieties of apple rootstocks('13#30''M9'and'10-1')as scions for budding.This experiment adopted the potted water control method for 60 days with two water treatments including normal water supply and moderate drought stress,and the treatment time is 60 days.We measured the instantaneous water use efficiency(WUEi)and long-term water use efficiency(WUEL)of the three varieties of apple rootstocks under drought stress,as well as related morphological and physiological indicators,and conducted correlation analysis on the above indicators.The results showed that after long-term moderate drought stress,significantly increased,the WUEi of the leaves of rootstock'M9'while the WUEi of the leaves of rootstock'13#30'decreased significantly.And the leaf WUEi rootstock'10-1'showed no significant variation.Meanwhile,at the end of drought treatment,the WUEL ranking of the three varieties of apple rootstocks was as follows:M9>13#30>10-1.Furthermore,WUEi showed a significant positive correlation with carotenoid content and soluble protein content(P≤0.05);WUEL showed a significant positive correlation with root to shoot ratio,CAT activity and proline content.And WUEL significantly negatively correlated with Pn,and extremely significantly negatively correlated with Tr(P≤0.01).This study has important guiding significance for the breeding and promotion of high WUE apple rootstock varieties,and provides a theoretical basis for evaluating the WUE of apple rootstocks.