Relationship between δ<sup>13</sup>C and photosynthetic parameters and their responses to leaf nitrogen content in six broadleaf tree species

Abstract

Stable carbon isotope composition (delta(13)C), net photosynthetic rate (P-N), actual quantum yield of photosystem 2 (PS2) electron transport (Phi(PS2)), nitrogen content (N-c), and photosynthetic nitrogen use efficiency (PNUE) in the leaves of six broadleaf tree species were determined under field environmental conditions. The six tree species were Magnolia liliflora Desr., M. grandiflora Linn., M. denudata Desr., Prunus mume (Sieb.) Sieb. et Zucc. cv. Meiren Men, P. mume (Sieb.) Sieb. et Zucc. f. alphandii (Carr.) Rehd., and P. persica (L.) Batsch. var. rubro-plena. The relationships among delta(13)C, Phi(PS2) P-N, and PNUE, as well as their responses to N-c in the six species were also studied. Both P-N and delta(13)C negatively correlated with N-c, but Phi(PS2) positively correlated with N-c. This indicated that with N-c increase, P-N and delta(13)C decreased, while Phi(PS2) increased. There were weak negative correlations between delta(13)C and PNUE, and strong negative correlations (p < 0.01) between Phi(PS2) and PNUE. According to the variance analysis of parameters, there existed significant interspecific differences (p < 0.001) of delta(13)C, P-N, Phi(PS2), PNUE, and N-c among the tree seedlings of the six tree species, which suggests that the potential photosynthetic capacities depend on plant species, irradiance, and water use capacity under field conditions.