外源激素IAA和GA_3对马尾松应压木形成的影响

Effects of exogenous IAA and GA_3 on formation of compression wood of Pinus massoniana Lamb

为丰富马尾松培育及材质改良的思路和方法,探索外源激素对马尾松应压木形成的影响。以人工倾斜45°的3年生马尾松作为试验材料,通过连续施加不同浓度的IAA、GA3、IAA＋GA3对枝条的生长进行调控,分别观测马尾松当年生枝条的长度,韧皮部、木质部的径向宽度,管胞长度、管胞壁厚,管胞数量,应压木的等级并比较相应差异,分析这两种激素对应压木形成的影响。结果表明：所有激素处理组枝条的增长率明显提高（89.6%～179.1%）;施加GA3、IAA＋GA3能促进枝条木质部和韧皮部的径向生长,但施加IAA对木质部、韧皮部的生长影响不显著;与空白对照组相比,GA3、IAA＋GA3处理组倾斜枝条下侧的管胞数量降低（14～17层）,上侧管胞数量上升（5～11层）;施加GA3、IAA＋GA3使倾斜枝条下侧形成中等应压木,对照组和IAA处理组倾斜枝条下侧均形成重度应压木。说明外源激素能促进马尾松倾斜枝条的顶端生长,在倾斜枝条上侧施加外源激素能抑制倾斜枝条应压木的形成。

The effect of exogenous hormones on the formation of compression wood of Masson pine（ Pinus massoniana Lamb.） was explored to enrich ideas and methods for the cultivation and quality improvement of Masson pine plantation. Three-year-old Masson pine seedlings were artificially inclined at angle of 45°at first,and then different concentrations of IAA,GA3 and IAA ＋ GA3 were added into the seedlings through cutting wound to adjust the growth of branches. In order to analyze the effects of these two exogenous hormones on the formation of compression wood of Masson pine,the differences and changes in longitudinal growth of previous-year（ 1-year-old） branches,radial widths of xylem and phloem,tracheid length,wall thickness,tracheid production and the severity of compression wood were observed and analyzed. The results showed that the longitudinal growths of previous-year（ 1-year-old） branches were increased in all hormone treatments（ 89. 6%- 179. 1%）. Radial widths of phloem and xylem were increased by adding GA3 and IAA ＋ GA3; however,the effects of IAA on radial widths of phloem and xylem were not significant. Compared with the control group,tracheid production was inhibited on the lower side（ 14- 17 layers） of tilt branch but was increased at the upper side（ 5- 11 layers） in all hormone treatments. Adding GA3 or IAA ＋ GA3 promoted the formation of mild compression wood at the lower sides of tilt previous-year（ 1-year-old） branches. Meanwhile,severe compression woods were formed at control group and IAA treatments for the same materials. Above results indicated that exogenous hormones can increase the top growth of Masson pine＇s tilt branches,and the formation of compression wood was inhibited by applying exogenous hormones on the upside of the Masson pine＇s tilt branches.