Response of carbon and nitrogen allocation in two hybrid poplar clones to soil nitrogen in Northern China

The response of poplar to nitrogen (N) fertilizer application varies with clones. Our objective was to quantify differences in resource allocation in two hybrid poplar clones due to nitrogen conditions. A two clone (46 and 107)-by-three nitrogen conditions (poor, medium and rich) factorial randomized design was replicated three times and undertaken in Mentougou District, Beijing, China. Biomass, TNC concentration and N concentration were determined at harvest maturity. Results revealed that clone 107 exhibited greater biomass in leaves and roots but less biomass in stems than clone 46 under poor and medium soil nitrogen conditions. Total non-structural carbohydrate allocation, especially the starch allocation in roots of clone 107 was greater than that in clone 46. Nitrogen concentration in leaves and stems were lower in clone 107 compared with clone 46, but higher nitrogen allocation in leaves and roots as well as N use efficiency of leaves and roots were detected in clone 107. There was no difference of endogenous resources between the two clones under rich soil nitrogen conditions. Our results suggest that clone 107 is more sensitive to poor N conditions than clone 46.