Effects of different N sources on growth, nutrient uptake and ionic balance ofLarlix gmelini seedlings

The effect of different sources and levels of N on dry matter production, nutrient uptake and ionic balance ofLarlix gmelini was studied. The results showed that the growth of the plants fertilized with ammonium was not as good as the control treatment. The growth of the plants fertilized with ammonium nitrate did not differ significantly from that in control or nitrate treatment, but was better than that in the ammonium treatment. Total cation concentrations in shoots varied little with N level in the ammonium and ammonium nitrate treatments, while those in the shoot increased with N level in the nitrate treatment. The treatments had little effect on the anion concentrations in the shoot. In the roots, the concentrations of both cations and anions changed little except for SO₄ ²⁻ and Ca²⁺. There existed a higher carboxylate production in the plants fertilized with nitrate. The ratio between the production of carboxylate and the production of organic N Δ(C-A)/ΔN_org was constant with N supply in the plants receiving nitrate, but obviously declined with N supply for ammonium-fed plants. Δ (C-A)/ΔN_org values were intermediate between those of the nitrate and the ammonium-fed plants as for the mixed N source. Foundation item: This paper was supported by “Hundred Scientists” Project of Chinese Academy of Sciences. Biography: CHEN Yong-liang (1969-), male, Ph. Doctor, lecture of Northeast Forestry University, Harbin 150040, Post-doctor in Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, P.R. China. Responsible editor: Song Fuman