泡桐修枝促接干技术及其效应的研究

Pruning Technique and Its Effects on Paulownia Trunk Extension

对2～5年生未接干泡桐修枝的研究结果表明,修除顶部分杈枝和部分下层枝是促进接干形成和生长的有效方法,最适宜修枝促接干的时期为造林后第3年的春季,适宜的修枝强度为50%～70%、保留下层2～3轮侧枝;按此法修枝,接干成功率达97 5%,接干高、径、接干形率在修枝当年可分别达5 7m、10 4cm、0 59,且具有不显著影响下部径生长和材积生长,而较显著促进上部径生长和显著促进主干总材积生长、降低原主干削度的效应;在对照采用高苗干、修枝处理采用矮苗干的情况下,修枝接干后的主干高仍要高于对照71 1%;5～6年生时接干与原主干已形成通直主干,接干材积已占总材积的27 1%～32 3%,与对照相比,原主干下部径生长及其材积无显著变化,而其上部径生长和主干总材积分别高7 2%～8 5%、42 2%～45 6%,且原主干的削度显著降低,形数极显著提高。

The result of pruning on 2～5 years old Paulownia trees without natural trunk extension showed, the effective way to promote trunk extension and its growth is to pruning the top branches and part of branches of lower canopy. The optimum pruning applications should be conducted in spring 3 years after plantation, under 50%～70% of pruning strength and leaving 2～3 layers of side branches. The successful rate of trunk extension by this method is 975% with the result of its height, diameter and form quotiety (FQ) of 57m, 104cm and 059, respectively; which had less effectives of affecting the growth of branches and the stock, but had much more effectiveness of promoting the growth of uppertrunk and stock of the main trunk, with the result of reducing the FQ of the formal trunk. Under the treatment of pruning on lowseedling with comparison of CK of highseedling, the height of the trunk is 717% higher than that of CK. After 2～3 years growth, the extension part combined well with the formal trunk whose stock reached 271%～323% of the whole volume. Compared with CK, there was no significant change of the growth of formal branches of lower canopy and its volume, on the other hand, the growth of the upper branch and standing stock of main trunk is 72%～85%, 422%～456% higher than that of CK, respectively; the treatment reduced the tapering grade, and at the same time enhanced the FQ.