At present, the plant species used for green roof are limited. In order to further expand the plant species used for green roof, it is particularly important to explore the adaptability of different plant species. In this study, 6 species of Crassulaceae (Kalanchoe blossfeldiana (K. blossfeldiana), Sedum lineare (S. lineare), Hylotelephium erythrostictum (H. erythrostictum), Phedimus aizoon (P. aizoon), Rhodiola rosea (R. rosea) and Sedum sarmentosum (S. sarmentosum)) were selected and planted on the stainless-steel planting rack on the roof with a substrate thickness of 15 cm. After normal maintenance and management for 1-month, continuous water deficit treatment was carried out. The physiological properties were measured at 0, 10, 20, 30 and 40 days, respectively. The results showed that:(1) The 6 species of Crassulaceae grew normally and well within 0-20 days. At 30 days, K. blossfeldiana had the most severe wilting rate (53%) and S. lineare had the least wilting rate (14%), but still maintained basic ornamental value. After 40 days of water deficit treatment, all the plants lost their ornamental value. (2) Among the 6 species under different water deficit treatment times, S. lineare and P. aizoon ranked between 1-3 in the 0-20 days when the water deficit degree was mild, and still ranked first and second in the 30-40 days when the water deficit was severe, with the best performance throughout the whole process, which could adapt to extensive green roof and did not need too much management. S. sarmentosum and K. blossfeldiana ranked 4-6 in the membership function under 40-day water deficit stress, with the worst performance. They are not suitable for extensive green roof and need careful management. In addition, considering the ornamental effect and ecological benefits of green roof, except K. blossfeldiana and S. sarmentosum, the other four plant species are suitable for the application of extensive green roof.

The construction methods of extensive green roof are different in different regional climate conditions, which are directly affected by weight load bearing capacity, planting substrate, plant species and other factors. In order to explore the planting types of extensive green roof suitable for warm temperate semi humid region, 12 plant species and 5 planting substrates were selected to conduct the experiment on the roof of the Architectural Art Museum (36°40'37"N, 117°11'25"E) of Shandong Jianzhu University, Licheng District, Jinan City, Shandong Province, China in March to October in 2019, and each plant species was planted on 5 planting substrates on the roof, respectively. By measuring the basic foundation layer load parameters, substrate bulk density and plant unit weight in the process of construction, the increase of planting weight load bearing capacity was calculated. After 4 weeks, the plant physiological indexes were tested. Finally, based on fuzzy mathematics subordinate function value method, combined with the plant physiological indexes, all combination types were comprehensively evaluated. The results showed that the unit weight of 12 plant species was divided into three categories, and the change trend of the weight load bearing capacity increase of each plant combined with the five planting substrates was similar to that of the five planting substrates. According to the comprehensive evaluation, 12 planting combinations were considered to be suitable for application on the extensive green roofs in warm temperate semi-humid areas. Compared with the plant weight, in the early stage of extensive green roof construction, the weight of planting substrate is the main factor leading to the change of weight load bearing capacity increase.