修枝促接干对泡桐叶片生长影响的研究

为揭示修枝促接干影响泡桐枝叶干相对生长关系的效应，采用全株测定方法对4年生修枝促接干和对照泡桐叶片的生长状况进行测定. 结果表明，修枝促接干对泡桐叶片生长的影响极为明显，表现在从单叶到单枝、冠层和全株等各级层面. ①使单叶的干重和面积明显提高，在树冠下层分别提高26.54%、28.78%，在树冠上层分别提高19.93%、23.71%，且有减小上下冠层间差异性的趋势. ②使单枝的叶片数、叶干重和叶面积在树冠下层分别提高48.59%、99.62%和98.51%，而在树冠上层分别降低33.29%、20.56%和17.59%，冠层间的差异性明显降低. ③使树冠上层的叶片数、叶干重和叶面积分别降低62.30%、55.10%和53.42%，同时使树冠下层的叶片数降低16.45%，而叶干重和叶面积反而分别提高12.22%和 11.61%，进而使全株的叶片数、叶干重和叶面积分别降低32.29%、22.88%和20.59%. ④修枝促接干使泡桐的侧枝数在树冠上层和下层均明显减少，但由于促进了新接干的形成和下层侧枝的发育和生长，其叶片数、叶干重和叶面积在总体上的降低幅度较小. 

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.