Comprehensive evaluation of four light green roof plants on drought resistance

In order to comprehensively evaluate the drought resistance of four light green roof plants including Alternanthera bettzickiana, Kalanchoe fedtschenkoi ‘Rosy Dawn’, Sedum polytrichoides and Callisia sp., their drought resistance was comprehensively evaluated using the method of membership function which combined their physiological indices under water stress in pots experiment, including the permanent wilting rate, leaf water losing rate, foliage relative water content, chlorophyll fluorescence parameters (Fv/Fm, Fv’/Fm’, ETR, ΦPSⅡ, NPQ) with their morphological changes during stress and rehydration. The results showed that K. fedtschenkoi ‘Rosy Dawn’ and Callisia sp. had relative low permanent wilting rate and leaf water losing rate which had strong drought resistance. With the extension of drought stress period, the leaf water losing rate of these 4 species decreased and the parameters of Fv/Fm, Fv’/Fm’, ETR, ΦPSⅡ, NPQ decreased in varied degree whereas NPQ increased. The drought resistance of these 4 species decreased in the following order Callisia sp.> K. fedtschenkoi ‘Rosy Dawn’ >S. polytrichoides>A. bettzickiana which consistent with the actual performance in pots. Callisia sp., K. fedtschenkoir ‘Rosy Dawn’ and S. polytrichoides can tolerated 12 days persistent naishdrought under high temperature conditions in summer in South China which suggested that these three species were suitable for light roof greening in this area.