Study on drought resistance and leaf structure in 10 species of garden shrubs in Chengdu

The leaf anatomical structure of 10 species of common garden shrubs in Chengdu were observed by paraffin sectioning and nail polish sealing. Indicators were measured and analyzed, which included thickness of main vein, thickness of leaf, cuticle thickness of upper epidermis, cuticle thickness of lower epidermis, thickness of upper epidermis, thickness of lower epidermis, thickness of palisade tissue, thickness of spongy tissue, stoma density of lower epidermis, stoma length, stoma width, and compactness and thickness ratio of palisade tissue to spongy tissue. Through variance and principal component analyses, representative indicators were selected, and drought resistance was evaluated among species by membership function. Results showed that the 13 indicators exhibited significant differences among the 10 garden shrubs, with variation coefficients ranging from 17.40%-68.20%. The 10 species belonged to bifacial leaves and their tissue structures were well recognized. The cuticle of the lower epidermis of Bougainvillea spectabilis Willd was too thin to obtain specific measurement data. Leaf structure compactness, ratio of palisade tissue to spongy tissue, stoma density, stoma length, stoma width, and thickness of palisade tissue were the main indices able to evaluate drought resistance of the 10 shrubs. Drought resistance in descending order was Loropetalum chinense var. rubrum Yieh, Schefflera octophylla(Lour.) Harms, Photinia fraseri Dress, Gardenia jasminoides Ellis, Rhododendron hybrida Hort., Pittosporum tobira(Thunb.) Ait., Camellia japonica L., Buxus bodinieriLevl., B. spectabilis Willd, Euonymus japonicus var. aureo-marginatus Hort. Furthermore, L. chinense var . rubrum Yieh, S.octophylla(Lour.) Harms, P. fraseri Dress, and G. jasminoides Ellis were strong drought resistant varieties and could be widely cultivated on roofs and slopes.