Studies On The Different Leaf Age Physiological Of P.cornutum And P.dolabratum Seedlings Under Drought Stress

Abstract P.cornutum and P.dolabratum seedlings were used as experimental material in this research. The effect of artificial imposed drought stress on physiological and biochemical responses mechanism of different leaf age P.cornutum and P.dolabratum seedlings'leaves and root(six-leaf stage) had been studied. And the determination of different leaf age tow species'lethal time under drought stress was made by rewatering the plants in the middle of stress treatment. The results were as the following:1) Under drought stress, the leaves relative water content (RWC) and chlorophyll (Chl) content of tow different leaf age speciesleaves decreased. The range decreased:two-leaf stage > four-leaf stage > six-leaf stage seedlings,The differences among four-leaf stage seedlings and six-leaf stage seedlings were not obvious; The range of MDA and PMP increased of different leaf age seedlings in one specie was same. which implied the four-leaf stage seedlings and six-leaf stage seedlings'drought adaptability is stronger than tow-stage seedlings.2) Under drought stress, the range of RWC,IUFA,Chl decreased and MDA,PMP increased of P.dolabratum was smaller than that of P.cornutum, and the quantity of yellow leaf of P.dolabratum was fewer than that of P.cornutum. Which implied P.dolabratum has better membrane stability and lower Chl degrading level and longer leaf live under drought stress.3) Under drought stress, the activity of tow species seedlings antioxidate system enzyme increased evidently. But the change of them was not same.4) Under rewater treatment, the lethal time of two-leaf stage seedlings under drought stress was 9 days. The lethal time of four-leaf stage and six-leaf stage P.cornutum seedlings under drought stress was10 days. The lethal time of four-leaf stage and six-leaf stage P.dolabratum seedlings under drought stress was11 days.We deduce that the drought resistant ability of two species'six-leaf stage,four- leaf stage seedlings are stronger than two-leaf stage seedlings, the drought resistance of P.dolabratum is stronger than that of P.cornutum.