当年和越年生香榧叶片的光合效率及抗氧化特性的季节性变化OA北大核心CSTPCD

[Objective]Determination of seasonal changes in chlorophyll fluorescence parameters,antioxidant enzymes,malondialdehyde(MDA)and other parameters in current and 1 year-old leaves of Torreya grandis'Merrillii'was to study the adaptive mechanism of the photosynthetic characteristics of T.grandis'Merrillii'leaves to temperature changes during season.[Method]The chlorophyll fluorescence parameters,specific leaf weight(SLW),antioxidant enzyme activity and soluble protein changes of T.grandis'Merrillii'leaves were measured in May,June,August,November and January of the second year.[Result](1)Compared with mid-May,ΦPSⅡ of T.grandis'Merrillii'leaves in mid-August was significantly up-regulated,while ΦNPQ was significantly down-regulated,and ΦNO with little change.SOD and CAT activities in T.grandis'Merrilli'current leaves were significantly increased,POD activity was significantly decreased,and MDA with little change.(2)Compared with mid-November,the average temperature in January of the second year decreased by nearly 10 ℃.ΦPSⅡ and ΦNPQ of T.grandis'Merrillii'current leaves and one-year old leaves decreased significantly,while their ΦNo and MDA content increased significantly.[Conclusion]Compared with mid-May,T.grandis'Merrillii'current leaves and one-year old leaves markedly improved ΦPS Ⅱ in mid-August is due to the high temperature and its leaves to absorb more light,and used for electron transfer,less dissipation of energy in the form of heat,the photosynthetic photoinhibition not occurring,its strong antioxidant enzyme system can coordinate to help them adapt to the high temperature specular environment.Compared with mid-November,T.grandis'Merrillii'current leaves and one-year old leaves suffered cold damage during overwintering in mid-January of the second year,and the photosynthetic organs of leaves suffered light damage.Above all,T.grandis'Merrillii'leaves are resistant to heat weather but not to cold weather,which may be the limiting factor of northern expansion.