Influence of Simulated Damage by Leaf-plucking on Growth of Poplar

In 1990～1992,a simulated leaf-plucking experiment was made to evaluate the influence of defoliator on growth of 2～3-year old Populus euramericana(Dode) Guinier cv.‘sacrau-79’.The results showed:for the treatment of less than 50% leaf-plucking,there was no significant decrease in diameter and height growth as compared with the control for the current and next year.For the leaf-plucking 75%～100% in April to July there was a significantly effect on the current year tree growth,leaf-plucking 75% reduced diameter growth 40.5%～69.4% and height growth 41.4%～58.7%.Leaf-plucking 100% reduced diameter growth 58.4%～89.8% and height growth 34.5%～65.2%.There was no significant effect for the leaf-plucking in August and September.But for leaf-plucking 75%～100% in June and September,there was a significant effect for next year growth.In April 47 days after leaf-plucking,for the 75% leaf-plucking,new leaves increased 2.9 times as compared with the control,while for leafplucking 100% increased 3.5 times.52 days after the leaf-plucking in July,fallen leaves for leaf-plucking 75% was 17.7% of the control.For leafplucking 100% there was a growth of 247 new leaves.