Evaluation of growth and physiological salt tolerance of 5 herbaceous plants

Five species of herbs, including Asparagus cochinchinensis, Wedelia chinensis, Sesuvium portulacastrum, Ipomoea pes-caprae, Gaillardia pulchella were studied. The growth and physiological characteristics of 5 tested plants were studied by means of two salt stress methods of roots and leaves, and their salt tolerance was comprehensively evaluated by principal component analysis and membership function analysis, and salt-tolerant plants suitable for planting on coastal sandy soil were selected to provide references for the treatment of coastal sandy soil by phytoremediation. The results showed that the growth of the five plants was inhibited by salt stress to different degrees. Under root salt stress, the RWC of Sesuvium portulacastrum in 0.1%(G₁) salt concentration group was significantly higher than that of CK, the RWC of Wedelia chinensis in 0.2%(G₂) and 0.3%(G₃) salt concentration groups was significantly higher than that of CK except day 28. The POD activity of Gaillardia pulchella was higher than CK in all treatment groups. The CAT activity of Wedelia chinensis, Sesuvium portulacastrum and Gaillardia pulchella was higher than CK. Under leaf salt stress, the RWC of Sesuvium portulacastrum in 0.2%(Y₁) salt treatment group was higher than CK, POD activities of Wedelia chinensi and Ipomoea pes-capra were higher than CK, and the RWC of Gaillardia pulchella in 0.3%(Y₂) salt treatment group was significantly higher than CK at the 14th and 28th days, POD activities of Wedelia chinensis were higher than CK. The CAT activities of Wedelia chinensis, Sesuvium portulacastrum and Ipomoea pes-capra were higher than those of CK in all treatment groups. Under the two salt stress modes, SPAD value of 5 tested plants in each treatment group was significantly lower than CK after 14 days of salt treatment, and MDA content was higher than CK during the whole salt stress stage. The salt tolerance of the 5 tested plants was evaluated comprehensively. The salt tolerance of the 5 tested plants was evaluated comprehensively. The salt tolerance of the 5 tested plants under root salt stress was ranked as Sesuvium portulacastru > Asparagus cochinchinensis = Gaillardia pulchella > Wedelia chinensis > Ipomoea pes-caprae. The order of salt tolerance of the five plants under salt stress was Wedelia chinensi > Sesuvium portulacastrum > Asparagus cochinchinensis > Gaillardia pulchella > Ipomoea pes-capra. The comprehensive analysis showed that Sesuvium portulacastru, Asparagus cochinchinensis and Wedelia chinensi showed stronger salt tolerance after root salt stress, while only Sesuvium portulacastru and Wedelia chinensi showed stronger salt tolerance after leaf salt stress, and hippocampi showed stronger salt tolerance after root and leaf salt stress.