The growth rate hypothesis （GRH） concerns the relationship between the stoichiometry of an organism and its growth rate. To verify the growth rate hypothesis, four samples of Leymus chinensis from different areas in Inner Mongolia and Jilin province were collected and cultured in pots under the same light, water and fertilizer conditions. The plant growth rate was measured by weighing method. The IGS （intergenic spacer） length of plants was measured by PCR method. The relationships between growth rate and content of N, P of plants; growth rate and IGS length; and growth rate and content of N, P of the sampling site soil were studied. The results showed as the following： there were a positive correlation between growth rate and content of plant P and a negative correlation between growth rate and N to P ratio of plants. The higher growth rate of plants had the longer IGS. These results accorded with the prediction of the GRH. The plants collected from the sampling site with higher content of soil N and P had higher growth rate, which might indicated adaptive evolution of L. chinensis to specific geographical habitat con-ditions in long-term. The higher growth rate and longer IGS length might be caused by the adaptation of L. chinensis to high content of N and P in the environment.
the growth rate hypothesis
N to P ratio