Abstract:Water is usually the limiting factor for the survival and normal growth of Poplar.The deep planting technique introduced from Italy can be helpful to solve this problem.According to the deep planting experimants thrice in Shansi,Inner Mongolia and Beijing,a survival rate by more than 95% was obtained and the early growth rate of newly planted trees was also increased under the condition.Without irragation deep planted Poplar trees have more and deeper roots and are also able to absorb the ground water directly through the end sections of the sets.This is the reason for high survival rate of the deep planting.The soil temperature of deep layer in the winter satisfies the demand of the sets for slow rooting.The sets deep planted in autumn have already rooted rather profusely before the opening of the buds in next spring.This benefit the survival of young trees planted in autumn. The transpiration rate of deep planted Poplar trees is higher by 2.3—4.4 times and its average daily water consumption of transpiration is higher by 1.83—15.41 times than those of trees planted in the ordinary way.In addition,compared with ordinary planting the deep planted Poplar trees have higher leaves water potential,higher water content and lower water saturated deficit.The active water metabolism shows the superiority of the deep planting technique.