Effects of pruning to promote trunk extension on leaf growth of Paulownia

Leaf growth of Paulownia under the treatments of pruning to promote trunk extension was investigated by using the method of whole plant analysis.The results showed that the pruning had great influence on such aspects as the single leaf,single branch,crown and whole tree:1) regarding to the single leaf,there was a tendency of lessening the difference of leaf growth parameters between the upper and lower crown,of which leaf dry weight (LDW) and leaf area (LA) were significantly enhanced by pruning by 26.54% and 28.78% in the lower crown and by 19.93% and 23.71% in the upper crown compared with the control;2) for leaves of a branch,pruning significantly lessened the differences of the parameters between the upper and lower crown,and increased its leaf quantity (LQ),LDW and LA in the lower crown by 48.59%,99.62% and 98.51%,while in the upper crown decreases by 33.29%,20.56% and 17.59%;3) for leaves of the whole crown,pruning decreased its LQ,LDW and LA in the upper crown by 62.30%,55.10% and 53.42%, while in the lower crown decreased its LQ by 16.45% but increased its LDW and LA by 12.22% and 11.61%,thereby decreased its total LQ,LDW and LA of the whole tree only by 32.29%,22.88% and 20.59%;4) although pruning reduced the lateral branches of upper and lower crown significantly,it evidently enhanced the formation of new trunks and the growth of branches of the lower crown,which nevertheless did not lead to an obvious decrease of LQ,LDW and LA as a whole.