Effects of Different N, P Addition Levels on Leaf Stoichiometry Characteristics of Flaveria Bidentis

Flaveria bidentis is a worst weed newly invaded in China, studying on its stoichiometry can help us understand its strategy to invade and adapt in different environments. In a green house, we studied the effect of soil N, P addition on F. bidentis plant growth, N, P stoichiometry characteristics and leaf chlorophyll content. The results showed that the effect of different N or P level on leaf N:P was significantly different with equivalent N:P ratio used. Leaf N:P was reduced significantly with N, P addition increasing, but above ground biomass was decreased also, this effect was mainly attributed to the amount of N used. When leaf N:P was larger than 21.24, plant growth rate became lower, which was in line with the growth rate hypothesis. Soil N and leaf N content had a positive correlation with leaf chlorophyll content of F. bidentis. Both F. bidentis leaf N (P) content and aboveground biomass were increasing firstly and falling later with soil N (P) content increasing. N and P were regarded as growth restrictive elements, when leaf N:P was below 20.86 and above 21.24, respectively.