Influence of nitrogen and phosphorus additions on parameters of photosynthesis and chlorophyll fluorescence in Cyclocarya paliurus seedlings

Abstract

Cyclocarya paliurus has been traditionally used as a functional food in China. A hydroponic experiment was conducted to determine the effects of N and P additions on photosynthesis and chlorophyll fluorescence (ChlF) of C. paliurus seedlings. N and P additions significantly altered photosynthesis and ChlF in the seedlings, but responses of these parameters to the N and P concentrations varied at different developmental stages. The greatest net photosynthetic rate (PN) and actual photochemical efficiency of PSII (ФPSII) occurred in the treatment of 150.0 mg(N) L–1 and 25.0 mg(P) L–1 addition, whereas the highest maximum quantum yield of PSII (Fv/Fm) and water-use efficiency (WUE) were recorded with 150.0 mg(N) L–1 and 15.0 mg(P) L–1 on the 60th day after treatment. Significantly positive correlations of PN with leaf relative chlorophyll content, transpiration rate, WUE, Fv/Fm, and ΦPSII, as well as the ФPSII with the Fv/Fm, were found. Our results indicated that an optimal addition of N and P nutrients depends on their coupling effects on the photosynthetic capacity and PSII photochemistry.