Effects Of Nitrogen Deposition And Phosphorus Addition On Photosynthesis And Chlorophyll Fluorescence Characteristics Of Chinese Fir

In order to investigate the effect of nitrogen(N)deposition and phosphorus(P)addition on photosynthesis and chlorophyll fluorescence parameters of 10-year-old Chinese fir(Cunninghamia lanceolata(Lamb.)Hook.),the filed experiment was builded and had nine treatments:low N(N30:30 kg·ha-1·a-1),high N(N60:60 kg·ha-1·a-1),low P(P20:20 mg·kg-1),high P(P40:40 mg·kg-1),low N with low P(N30+P20),low N with high P(N30+ P40),high N with low P(N60+P20),high N with high P(N60+P40)and control group(CK).In summer,N deposition and P addition had no significant effect on the maximum net photosynthetic rate(Pn max)of Chinese fir.P addition increased the leaf color value(SPAD)of Chinese fir;In autumn,N deposition significantly promoted the Pn max.Either N deposition or P addition significantly inhibited the SPAD;In winter and spring,N deposition or P addition significantly increased the Pn max and SPAD.P40 in combination with both N depositions(N30 and N60)significantly increased the Pn max,SPAD value,maximum fluorescence yield(Fm)and initial fluorescence yield(F0)than the P addition alone(P<0.05).SPAD value was significantly and positively correlated with N content of leaves in summer(P<0.01);Pn max was significantly and positively correlated with P content of leaves(P<0.01).N content of leaves were remarkably and negatively correlated with SPAD value and photochemical quenching coefficient(qP)(P<0.05)in autumn,but positively correlated with Fm and F0(P<0.05);P content of leaves were significantly and positively correlated with Pn max(P<0.05).P content of leaves were significantly and positively correlated with Fn and F0 in winter(P<0.01).N content of leaves were significantly and positively correlated with Fm,F0 and actual quantum yield(Y(Ⅱ))(P<0.05)in spring,but negatively correlated with non-photochemical quenching coefficient(qN)(P<0.01).P content of leaves were significantly and positively correlated with Pn max,SPAD value and Y(Ⅱ)(P<0.05),but negatively correlated with qN(P<0.01).P addition in combination with N depositions significantly increased the photosynthesis and chlorophyll fluorescence parameters of Chinese fir.