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

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 leaf stomata 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.