Relationship between leaf δ^13C, δ^15N and nutrient content’water use efficiency in Camellia oleifera

Using 4 different Camellia oleifera species as test materials, stable carbon and nitrogen isotope ratios (δ^15N and δ^13C), water use efficiency（WUE）and contents of C, N, P and K in leaf were determined and the relationship between leaf δ^13C, δ^15N and nutrients contents or WUE was analyzed. The results showed that the δ^13C values of 4 different C.oleifera species were between -29.55‰and -27.52‰, which of Huaxin was significantly higher than those of other 3 species; the δ^15N values were from -2.43‰to 0.64‰, which of Xianglin XCL15 was the highest, while the lowest was observed in Huashuo. The WUE of Huajin was 3.35 μmolCO2/mmol H2O, which was higher than those of other 3 species. The contents of C, N, P, K in leaves were respectively from 51.02%-53.11%, 1.40%-1.82%, 1.03-1.12 g/kg and 13.72- 14.30 g/kg, N and P contents in leaves showed great difference among the plant species, Huajin contained the highest level of N and P, and the highest level of C element appeared in Xianglin XCL15, K element of Huasuo was more than those of other pieces. Leaf δ^13C showed a significantly positive correlation with N content and WUE, and was extremly significantly negatively correlated with P , K contents; but δ^15N was not correlated with nutrient content and WUE.