Abstract:

The responses of physiological characteristics of garden trees to different seasons were studied in Yan’an City. Taking the six garden tree species in the campus of Yan’an University as the research object, including Pinus tabuliformis, Platycladus orientalis, Salix matsudana, Styphnolobium japonicum, Ginkgo biloba, Koelreuteria paniculata, tree leaves were collected in spring, summer and autumn to compare the physiological characteristics between deciduous arbors and evergreen. The results showed that the relative water content and POD content of Pinus tabuliformis and Platycladus orientalis were higher than other four deciduous arbors, but the conductivity, MDA, SOD and CAT content were lower than other deciduous arbors on average. Evergreen had higher water-retaining property than deciduous arbors, and deciduous arbors were much vulnerable to drought impact, but they had high capability in respond to drought. The physiological characteristics of garden trees were different in different seasons. The relative water content and POD content were in the order of summer>spring>autumn, in contrast with CAT content. The conductivity and MDA content were in the order of autumn>summer>spring. The activities of SOD was in the order of summer>autumn>spring. The results indicated that the climate environment had higher influence on garden trees in autumn. It should pay attention to management and protection in autumn. The subordinate function showed that the adaptive characters were difference among different tree species, and were not consistent between different seasons. The mean membership function value of deciduous arbors was higher than that of evergreen. In all, the membership function analysis revealed that the environment adaptiveness of six garden trees was in the order of Koelreuteria paniculata> Styphnolobium japonicum> Ginkgo biloba> Platycladus orientalis> Pinus tabuliformis.

Key words: garden tree, leaf physiological characteristics, antioxidant enzymes, subordinate function method, season change