关键词: 解剖结构, 保水结构, 输水结构, 土壤水分梯度, 草酸钙含量

Abstract: In order to reveal the habitat adaptive capacity of the invasive species Bistorta macrophylla in the process of drought in alpine meadows,we selected humid,subhumid and drought habitats in the alpine meadows of the Baima Snow Mountain in northwestern Yunnan Province to set up sampling plots and collect experimental materials. Changes in leaf anatomy and calcium oxalate content along habitat drought were investigated using one-way ANOVA and principal component analysis. The results showed that the palisade tissues were tightly arranged in 2 layers,5~9 vascular cylinder in the main veins were arranged in a ring,and the xylem was distributed towards the center of the ring. Leaf thickness,upper epidermal and stratum corneum thickness,lower epidermal thickness,palisade(P) and spongy(S) tissue thickness,main vein and vascular cylinder thickness,xylem and phloem thickness,and leaf calcium oxalate content differed significantly among habitats and had the greatest values in the drought habitats (P <0.01),with the leaf calcium oxalate content contributing the most to the drought tolerance of B. macrophylla. Lower epidermal stratum corneum thickness and P/S did not differ significantly among habitats. Under drought stress,B. macrophylla reduced water evaporation by increasing the thickness of water retaining structures (epidermis,epidermal stratum corneum),improved water transport efficiency by increasing the thickness of water transporting structures (vascular cylinder,xylem),and enhanced the water storage capacity by increasing the calcium oxalate content. Namely,the strategies of enhancing the function of water retaining and water transporting structures and increasing the coordinated response of anatomical structures and calcium oxalate content were used to resist the drought of the habitat.

Key words: Anatomical structure, Water retention structure, Water transport structure, Soil moisture gradient, Calcium oxalate content