中国东北温带3种木质藤本植物细根解剖和形态性状研究

【目的】研究温带木质藤本植物细根的功能性状及其潜在吸收能力。【方法】选取中国东北温带3种代表性木质藤本植物,即缠绕类藤本狗枣猕猴桃和北五味子、卷须攀援类藤本山葡萄为材料,研究了1~5级细根的解剖、形态、分支结构和吸收根组成。【结果】随着根序的增加,狗枣猕猴桃和北五味子的皮层厚度有增加趋势,而山葡萄则呈降低趋势。3种藤本植物的中柱直径均随根序增加而显著增粗,但是皮层厚度与中柱直径比值显著下降。皮层的存留状态显示,所有树种吸收根的比例均随根序增加而明显下降,1级根是典型的吸收根。从1级根至5级根,3种藤本植物比根长显著降低,直径显著增粗,组织密度增加,但是分支比仅在山葡萄中呈现单调的降低趋势。树种对各根系性状有显著的影响,但是与根序的影响存在交互作用。与其他2个缠绕类藤本植物相比,卷须攀援类藤本山葡萄中柱直径较大,皮层厚度与中柱直径比值较低,而2、3级根的分支比明显更高。与本地区其他类群植物相比,3种藤本植物1级根的平均直径较粗、比根长较低,而平均组织密度介于草本蕨类和其他木本植物之间。【结论】细根解剖和形态性状在3种藤本植物间存在明显差异,但是这些性状随根序变化的规律与其他木本植物较一致。与本地区其他类群植物相比,藤本植物1级根形态特征表现出了较为独立的特点。

Fine root anatomical and morphological traits of three temperate liana species in northeastern China

Objective] The objective was to investigate the functional traits and potential absorbing capacity in fine roots of liana(woody climbing plants) in temperate forests. Method] We sampled three typical temperate liana species in northeastern China, including two twining climbers(Actinidia kolomikta and Schisandra chinensis) and one tendril climber(Vitis amurensis). The anatomical, morphological, and branching traits, as well as the composition of absorptive roots were examined for the grade 1-5 fine roots in the three species. Result] The results showed that the cortical thickness of Actinidia kolomikta and Schisandra chinensis increased by ascending branch order, while that of Vitis amurensis decreased. The stele diameter of all three liana species significantly increased with increasing branch order, but the ratio of cortical thickness to stele diameter significantly reduced. In term of the status of cortex appearance, the proportion of roots with absorbing function apparently decreased with ascending branch order across all three species, with the grade 1 fine roots as typical absorptive roots. From grade 1 to 5, specific root length significantly decreased, but root diameter and tissue density increased. The decline in root branching ratio associated with increasing branch order was only found in V. amurensis. Those root functional traits in liana were significantly influenced by tree species, but showing significant interaction with branch orders.Compared with two twining climbers, tendril climber of V. amurensis had wider stele, lower ratio of cortical thickness to stele diameter, and much higher branching ratio to the grade 2 and grade 3 roots. In comparison to other woody plants and herbaceous ferns at the same study site, mean root diameter of three liana species was thicker but mean specific root length was lower, with intermediate mean tissue root density.Conclusion] Although the interspecific differences in root anatomical and morphological traits exist in three temperate liana species, the variation patterns of those root traits associated with increasing branch order are consistent with other woody plants. The morphological traits of the grade 1 roots in these lianas display distinctive characteristics compared with other plant taxa in this region.