云南松苗木萌枝能力对截干高度的响应

Response of sprouting ability of Pinusy unnanensis seedlings to stump-cut hei

【目的】探讨截干高度对云南松苗木萌枝能力的影响,为采穗圃穗条生产和适宜截干高度的确定提供技术支撑。【方法】以1年生云南松播种苗为试验材料,采用单因素完全随机区组试验,设置截干高度(即留桩高度)5,10和15 cm 3个处理,以不截干为对照,截干后每月测定萌枝数量和萌枝生长量,年底测算萌枝保存率和母株保存率,分析不同截干高度下萌枝数量和萌枝生长量的变化进程及累积数量的变化规律,并结合萌枝和母株保存率,探讨萌枝能力对截干高度的响应规律。【结果】不同截干高度萌枝发生的进程有所差异,截干高度5 cm萌枝数量速生期开始最早(截干后15 d)、持续时间最短(22 d),而截干高度10 cm萌枝数量速生期开始最晚(截干后22 d)、持续时间最长(39 d);净萌枝数量增加集中在截干后1~2个月的速生期内,占理论极值的57.51%~58.55%;不同截干高度的净萌枝数量和累积萌枝数量在生长前期、速生期、生长后期均表现为截干高度5 cm<截干高度10 cm<截干高度15 cm;截干高度5,10和15 cm的平均单株累积萌枝数量分别为12.82,19.72和22.71枝/株,不同处理间存在显著差异(P<0.05)。不同截干高度云南松苗木的萌枝平均生长量积累过程呈现“慢-快-慢”的节律,截干高度5,10和15 cm的萌枝生长量分别为6.094,5.486和7.868 cm,处理间无显著差异(P>0.05);云南松萌枝生长量增加集中在截干处理后1~3个月,占总萌枝生长量的70%以上。截干高度5,10和15 cm的萌枝存活率分别为86.14%,76.26%和63.48%,不同处理间差异显著(P<0.05);母株保存率分别为95.83%,100%和100%,不同处理间无显著差异(P>0.05)。综合来看,截干高度5 cm的萌枝数量少,但存活率最高;截干高度10 cm的萌枝数量多,且存活率较高;截干高度15 cm的萌枝数量多,但存活率最低。【结论】截干高度10 cm的处理既利于枝条萌发和萌枝生长,又具有较高的萌枝存活率,可较好权衡萌枝数量、生长量和存活率之间的关系,因此确定其为最有利于萌枝潜力发挥的适宜留桩高度。

【Objective】This study discussed the effect of stump-cut height on sprouting ability of Pinus yunnanensis Franch seedlings to provide support for sprouts production and determination of appropriate stump-cut heights.【Method】The field test was set with one-year-old P.yunnanensis seedlings as experi-mental material.A single factor completely randomized block design was used with three stump-cut heights(mother tree heights after stumping)of 5,10 and 15 cm using non-stumping as control.The number and growth of sprouts were measured monthly after stumping,and the survival rates of sprouts and mother trees were measured at the end of the year.The changes in number and growth of sprouts under different stump-cut heights were analyzed.The responses of sprouting ability to stump-cut heights were analyzed in combination with survival rates of sprouts and mother trees.【Result】The process of sprout occurrence varied at different stump-cut heights.The rapid growth stage of sprouts number of 5 cm treatment started the earliest(15 d after stumping)but lasted for the shortest time of 22 d.For the stump-cut height of 10 cm,it started the latest(22 d after stumping)and lasted the longest(39 d).The increase of net number of sprouts concentrated at the rapid growth stage,which was 1-2 months after stumping,accounting for 57.51%-58.55%of the theoretical maximum value.The net number and cumulative number at early,rapid and late growth stages were in the increasing order of stump-cut height 5 cm<stump-cut height 10 cm<stump-cut height 15 cm.The average sprouts per tree were 12.82,19.72 and 22.71 branches for the treatments,with significant differences(P<0.05).The accumulation process of average sprouts growth of P.yunnanensis seedlings with different stump-cut heights showed a“slow-fast-slow”trend.The sprout growth amounts of 5 cm,10 cm and 15 cm treatments were 6.094,5.486 and 7.868 cm,without significant differences(P>0.05).The sprouts growth of P.yunnanensis seedlings was concentrated in 1-3 months after stumping treatments,which accounted for more than 70%of total growth.The survival rates of sprouts were 86.14%,76.26%and 63.48%for stump-cut height treatments of 5 cm,10 cm and 15 cm,re-spectively,and there were significant differences among different heights(P<0.05).The survival rates of mother trees with 5,10 and 15 cm stump-cut heights were 95.83%,100%and 100%,respectively,and there was no significant difference(P>0.05).Comprehensively,the treatment of 5 cm stump-cut height had less sprouts and the highest sprout survival rate,the treatment of 10 cm had more sprouts and higher sprout survival rate,while the treatment of 15 cm had the most sprouts and the lowest sprout survival rate.【Conclusion】Conducive to sprout occurrence and growth with higher sprout survival rate,stump-cut height of 10 cm was determined the most suitable to balance the relationship between sprout number,sprout growth and sprout survival rate.