基于叶片解剖结构对青藏高原25种灌木的抗旱性评价

Drought resistance evaluation based on leaf anatomical structures of 25 shrubs on the Tibetan Plateau

【目的】研究青藏高原25种灌木叶片解剖结构和气孔特征,了解其水分适应机制,为青藏高原地区造林筛选优良耐旱植物提供参考依据.【方法】通过常规石蜡切片技术,对比叶片角质层、上下表皮、栅栏组织、海绵组织和叶片厚度等12项指标,运用主成分分析和隶属函数法对供试植物进行抗旱性能分析与评价.【结果和结论】25种植物叶片具有典型的旱生结构,叶片厚度最高为323.00μm、平均为186.25μm,上表皮角质层厚度最高为4.83μm、平均为1.71μm,上表皮平均比下表皮厚30.00%,气孔小而密集,这是植物长期适应高原干旱环境的进化结果,12项指标的种间差异极显著.通过主成分分析法结合各指标的变异系数筛选出5项具有代表性的抗旱指标:气孔密度、叶片厚度、栅栏组织厚度、海绵组织厚度和角质层厚度,运用隶属函数值法对各树种的抗旱性能评分排序,将25种植物分为抗旱性极强树种、抗旱性较强树种、抗旱性一般树种和抗旱性较弱树种.

【Objective】This study reported the leaf anatomical structure,stomatal characteristics,and the response mechanism of water adaptability of 25 shrubs on Tibetan Plateau,with an aim to provide a reference beneficial to afforestation and selection of drought-resistant plants on the Tibetan Plateau and an attempt to outline how to screen excellent drought-resistant plants. 【Method】Conventional paraffin section technique was used to make comparison with 12 indexes such as the thickness of leaf cuticle,upper epidermis,lower epidermis,palisade tissue,spongy tissue,and leaf thickness. The principal component analysis and subordinate function were used to develop a system to analyze and evaluate the plant drought resistance. 【Result and conclusion】The result showed that the leaves of all the 25 shrubs had typical xeromorphic structures,and the maximum leaf thickness was up to 323. 00 μm,186. 25 μm on average,and the maximum epidermal layer thickness was up to 4. 83 μm,with an average of 1. 71 μm,which presented that upper epidermis was 30. 00% thicker than lower epidermis averagely,proving that the leafstomata were small and dense as the result of long-term adaptive evolution in a drought plateau environment. Moreover,12 indicator species differed from each other significantly. The five representative drought resistance indexes,including stomatal density,leaf thickness,palisade tissue thickness,spongy tissue thickness and stratum corneum thickness had been screened through a principal component analysis combined with the variation coefficient of each index. By using the method of subordinate function values,this study provides a sketch of content on sorting drought performance into different levels,including highly drought-resistant species, drought-tolerant species, drought-resistant in general species, and drought-sensitive species.