Effects of drought stress on leaf gas exchange parameters of four seedlings

The effects of drought stress on leaf gas exchange of four seedlings of Syzygium jambos,Kadsura longipedunculata,Ormosia pinnata and Mangliet iaglauca were studied.The results show that net photosynthetic rate(Pn),stomatal conductance(Gs) and transpiration rate(Tr) of the four seedlings continuously decreased with increasing drought time.Intercellular carbon dioxide concentration(Ci) of S.jambos decreased,whereas its stomatal limits(Ls) first decreased and then increased,whereas intercellular carbon dioxide concentration(Ci) decreased and then increased,the Ci of K.longipedunculata,O.pinnata decreased followed by an increase;the Ci of M.iaglauca increased and its Ls decreased during drought experiment period.Water use efficiency(WUE) of S.jambos increased and that of other seedlings decreased with increasing drought time.The drought resistance of the four seedlings was evaluated by using principal component analysis,and the order of drought resistance was S.jambosK.longipedunculataO.pinnataM.iaglauca.