[Effects of NO3- stress and recovery on chlorophyll fluorescence parameters and Atpase activities of cucumber seedling leaves].

With water culture, this paper studied the effects of NO3- stress and recovery on the chlorophyll contents, chlorophyll fluorescence parameters, and ATPase activities of cucumber seedling leaves. The results showed that under stress for 7 days, the chlorophyll a, chlorophyll b, total chlorophyll and carotenoid contents, intrinsic fluorescence (Fo), and Mg-ATPase and Ca-ATPase activities were increased significantly when the NO3- concentration was high (168 mmol x L(-1)), while the intrinsic photochemical efficiency (Fv/Fm), potential activities (Fv/Fo) and quantum yield (phiPS II) of PSII were decreased with increasing NO3- concentration. After recovery for 7 days, the chlorophyll and carotenoid contents of all treatments with NO3- were lower than CK, while the intrinsic fluorescence, intrinsic photochemical efficiency and quantum yield of PS II were similar to CK when the NO3- concentration was < or = 84 mmol x L((-1), and the Fv/Fm and phiPS II were significantly lower than CK when the NO3-concentration was > 84 mmol x L(-1). The potential activity of PS II was similar to CK when the NO3- concentration was 42 and 126 mmol x L(-1), but significantly lower than CK in other treatments. The activities of Mg-ATPase and Ca-ATPase were decreased firstly but increased then when the NO3- concentration was > 84 mmol x L(-1).