title: [Effect of different nitrogen supply on Fraxinus mandshurica seedling's biomass, N partitioning and their seasonal variation].
abstract: Nitrogen is one of the most important limiting nutrients for tree growth in temperature forest ecosystems. In this paper, the effects of nitrogen treatments on nitrogen partition and biomass allocation in roots and leaves of one-year-old Fraxinus mandshurica seedlings were studied during a five-month period. The plants were sand-cultured in pots supplied with various concentrations of N (1, 4, 8, 16 mmol x L(-1)). The results suggested that N supply could significantly increase the N concentration in roots and leaves. In the initial (June) and middle growth stage (July and August), the N concentration in leaves was over 9.40, 9.55 and 4.21 mg x g(-1) respectively, which was higher than that in roots, but in the latter growth stage (September), it was lower than that in roots. From June to September, the N content of whole plant increased markedly, and was 4 times more in September than in June. The N content in Ash seedlings varied with N supply. It increased by 5.5 times in 16 mmol x L(-1) N treatment, in comparing with 1 mmol x L(-1) N treatment in September. The N allocation also varied in leaf, stem, and root. The proportion of N allocation in leaf was the highest in June (43% in average), and the lowest in September (9% in average). The proportion of N allocation to root increased with plant growth, which was the highest in September (81% in average). Regardless N treatments and tree growth stages, the proportion of N allocation to root was the highest, followed by to leaf, and the lowest was to stem. These results provided the theoretical foundation for the further studies of nitrogen absorption and carbon allocation mechanism in root system of Manchurian ash.
authors.affiliation: School of Forestry, Northeast Forestry University, Harbin 150040, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Fan
authors.forename: Zhengquan
authors.initials: Z
authors.lastname: Wang
authors.forename: Chu
authors.initials: C
authors.lastname: Wu
authors.forename: Hongxin
authors.initials: H
authors.lastname: Li
mesh_terms: D018533:Biomass; D017753:Ecosystem; D031661:Fraxinus / Q000254:growth & development* / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis*; D012621:Seasons; D036226:Seedlings / Q000254:growth & development* / Q000378:metabolism
chemical_list: D009584:Nitrogen