Effects of Drought Stress on Free Proline and Malonaldedyde Contents in Potato Leaves and Correlation Analysis of Drought-tolerant Level among Different Varieties

Under the drought-stress conditions in greenhouse,the variation effects of drought stress on free proline content and malonaldedyde(MDA) content in potato leaves were investigated and the correlation analysis of drought-tolerance level was conducted.The variance analysis of potato yield and yield coefficient under drought stress and routine irrigation conditions showed that Zuoliyangyu was the most drought-tolerant variety,PI34,Ninglan182 and Ninglan152 were more tolerant,and Maerke,Yongdezipi,Jiabanyangyu and Jianchuanghong performed worst.Under the drought-stress conditions,the free proline content and MDA content in potato leaves were all increased in contrast to that of routine irrigation,the increasing times of proline content fluctuated from 1.01 to 5.40 among different varieties,and MDA content from 1.10 to 1.91.In addition,the relative values of both free proline content and MDA content correlated positively and significantly with root polling resistant coefficient and yield coefficient of corresponding varieties.Therefore,the relative values of free proline content and MDA content could be used as physiological parameters to evaluate drought tolerance level during early stage of potato plant growth.