Identification and Evaluation of Waterlogging Tolerance of 43 Clematis varieties

Waterlogging tolerance was the key to Clematis application, and identification of waterlogging tolerance was important for introduction and domestication of Clematis and stress resistance breeding. In this study, the phenotype of 43 Clematis horticultural varieties after waterlogging stress was analyzed, and four appearance morphological indexes （leaf color, leaf shape, stem color and stem shape） were qualitatively graded. Combined with the physiological indexes of relative conductivity, relative water content and chlorophyll content, principal component analysis and cluster analysis were used to comprehensively evaluate their waterlogging tolerance. The results showed that the relative water content, chlorophyll a, chlorophyll b, total chlorophyll and carotenoid contents of Clematis leaves decreased after waterlogging stress, while the relative conductivity increased. Leaf water content, leaf color, leaf shape, stem color and stem shape were significantly correlated with electrical conductivity, and the total evaluation score of waterlogging tolerance was significantly correlated with electrical conductivity, leaf color, leaf shape, stem color and stem shape. Forty-three Clematis horticultural varieties were classified into waterlogging tolerant types, intermediate types, intolerant types and extremely intolerant types by cluster analysis, including 2 waterlogging tolerant types, 16 intermediate types, 6 waterlogging intolerant varieties and 19 extremely intolerant Clematis. The characteristics of waterlogging tolerance classification of 43 Clematis avarieties were preliminatively identified. An evaluation system of Clematis waterlogging tolerance was initially established to provide reference for identification of Clematis waterlogging tolerance.