修枝促接干对泡桐枝生长动态影响的研究

Effects of Pruning to Promote Trunk Extension on Annual Growth Dynamic of Paulownia Branches

为揭示修枝促接干影响泡桐枝叶干相对生长关系的效应,在造林后第3年对5种处理(4种处理和对照CK)泡桐的枝基径(Db)和基部断面积(Sb)(包括单枝、冠层和全株)的年生长动态进行测定分析,并采用Richards函数进行模拟.结果表明:①在修枝促接干时保留下层3～6枝为适宜的留枝量,这可使上冠层接干枝的Db和Sb年生长量分别达12.16～12.25 cm、117.550～120.786 cm2,同时使下冠层的Db年生长量不致过大、而其冠层Sb年生长量达107.748～113.291 cm2,从而使其全株Sb年生长量达228.535～230.841 cm2,均明显高于CK和其它处理,其Sb总量亦达287.907～294.535 cm2,稍高于CK.②各处理各枝指标的年生长动态均可用Richards函数进行可靠描述,并分别确定了最大年生长量(A)、最大连日生长量(AGRmax)、平均连日生长量(Am)、速生期(T)、生长期(Dg)和速生点、速生期开始时间和结束时间等生长参数,通过分析修枝促接干对各枝指标各生长参数的影响得出,在修枝促接干时保留下层3～6枝可使各枝指标年生长的速生期和生长期相对较长,并使其Db生长的AGRmax(或Am)和A在上冠层达到最大,较CK分别高230.76%～240.19%、234.93%～245.46%,而在下冠层则不致过大;同时使其Sb生长的AGRmax(或Am)和A与CK相比在上冠层分别高70.69%～78.78%、35.85%～41.38%,在下冠层分别高105.43%～127.17%、143.46%～155.86%,在全株分别高61.95%～76.02%、81.38%～85.22%.

In order to know thoroughly the effects of pruning to promote trunk extension on 3-year-old Paulownia relative growth among branche, trunk and leaf , the annual growth dynamic processes of the base diameter Db and base cross sec tion area Sb of branches from single branch to crown layers to the whole tree under 4 pruning treatments and control were measured and analyzed and luther simulated by Richards＇ functions. The results showed that ： （ 1 ） the treatment of remaining 3 -6 underlayer branches after pruning was optimal for promoting the branch growth. Under this treatment, the an-nual increments of Db and Sb in the upper crown may reach to 12.16 - 12.25 cm and 117. 550 - 120. 786 cm^2, while in the lower crown the former to a mediate level and the latter to 107. 748 -113. 291 cm^2, thereby the annual increment of Sb of the whole tree reached to 228. 535 - 230. 841 cm^2, being much higher than that of the control and other pruning treatments, as a result its total Sb reached to 287. 907 - 294.535 cm^2, being little higher than that of the control. （2） All of the annual growth dynamic processes of Db and Sb under treatments and control could be simulated reliably by Richards＇ function and their parameters of maximum annual increment A, maximum daily increment AGRmax, average daily increment Am, fast-growing period T, growing period Dg, and fast growing point, the initial and final time of fast-growing period were determined and analyzed. The analysis showed that the optimal treatment had relatively longer T and Dg, and maximized AGRmax （ or Am ） and A of Db in the upper crown which were 230.76% - 240.19% and 234.93% - 245.46% higher than that of the control, but got a moderate level in the lower crown. Meanwhile, compared with the control, the AGRmax （ or Am）and A of Sb were 70.69% - 78.78% and 35.85% - 41.38% higher in the upper crown, while 105.43% - 127.17% and 143.46% - 155.86% higher in the lower crown, congsequently 61.95% - 76.02% and 81.38% - 85.22% of the whole tree.