Drought resistance of Populus euphratica and Populus bolleana seedling under different irrigation regime

Two years old seedlings of Populus euphratica and Populus bolleana were chosen and planted,and then treated by different amount of irrigation in Moyu county,Xinjiang.The relative mean soil water contents of different irrigating treatment were 85%,70%,47% and 24% of field capacity.The leaf water potential of P.euphratica and P.bolleana under different conditions and at different time was shown variation trends of "V" figures in a day.The mean daily water potential of P.euphratica was higher than P.bolleana.The net photosynthetic rate,transpiration rate and transient water use efficiency of P.euphratica were higher than P.bolleana.The leaf δ13C value of P.euphratica was significantly higher than P.bolleana.The drought resistance of P.euphratica is higher than P.bolleana by Subordinate Function Value.