Analysis on Dynamic Characteristics and Influencing Factors of Leaf Water Potential of Seven Landscape Tree Species in Beijing

Seven common landscape tree species of Pinus bungeana,Platycladus orientalis,Sabina chinensis,Sabina vulgaris,Ginkgo biloba,Koelreuteria paniculata,and Sophora japonica were used as experimental materials to study the dynamic characteristics and influencing factors of leaf water potential of seven landscape tree species by pot control method,in order to clarify the water deficit status and drought resistance mechanisms of plants and provide reference for the selection of landscape tree species in Beijing.The results showed that under good water supply treatment,the diurnal variations in leaf water potential of S.chinensis,P.bungeana,S.vulgaris,P.orientalis,G.biloba,and S.japonicaall presented a trend of high in the morning and evening,and low at noon.There was a very significant difference in the diurnal variation trend of K.paniculataand other tree species（P＜0.01）.Its leaf water potential rose briefly from 12:00 to 14:00,and then increased again with time.The daily variation of leaf water potential of evergreen tree species was significantly lower than that of deciduous tree species（P＜0.05）.The monthly change in leaf water potential of each experimental tree species from July to October showed a gradual upward trend.The leaf water potential with sufficient soil water content was significantly negatively correlated with solar radiation and atmospheric temperature（P＜0.01）,and positively correlated with atmospheric relative humidity（P＜0.01）.There was no significant difference in the degree of influence of solar radiation on leaf water potential between different tree species.The impacts of atmospheric temperature on the leaf water potential of S.japonica and P.bungeanais were stronger than that of other tree species.P.orientalis,G.bilobaand K.paniculata were more susceptible to atmospheric relative humidity than other tree species.The main meteorological factor that affected the changes in leaf water potential of S.chinensis,P.orientalis,and S.japonica was atmospheric relative humidity,while the atmospheric temperature was the dominant meteorological factor functioning leaf water potential of P.bungeana,S.vulgaris,G.biloba,and K.paniculata.