Effects Of Nitrogen On Growth Of Schisandra Chinensis Seedlings

Nitrogen is one of the main limiting factors for growth of Schisandra chinensis. During practice of production, as lacking theoretical guide, excessive fertilization causes decrease of productivity and severe environmental pollution. Therefore, to provide theoretical basis for nutrients regulation of biomass accumulation and scientific manuring, physiological and photosynthetic properties of Schisandra chinensis seedlings under different nitrogen levels and forms were studied.The subjects are the two-year old Schisandra chinensis seedlings. Under field condition, treatment of different nitrogen levels (0,50,100,150,200,300 kg.ha-1) and different ratios of nitrogen forms (ratios of ammonium nitrogen and nitrate nitrogen are 100:0,75:25,50:50, 25:75,0:100 respectively) are applied. From the last ten-day of June, indicators, such as photosynthetic rate, soluble protein in leaves, chlorophyll content, total-N content in roots, stems and leaves, biomass and son, are measured. Then effect of nitrogen levels and forms on growth of Schisandra chinensis was discussed, that is:1. Along with increase of nitrogen levels provided, content of total-N, soluble protein and chlorophyll in stems and leaves of Schisandra chinensis start to increase and then decrease, and peak values showed in different growth period are different. During the complete process of growth, all indicators kept lower levels under treatment provided without nitrogen. During the earlier stage of growth (June), differences of maximal photosynthetic rate among treatments provided with nitrogen aren't significant, but higher than treatment provided without nitrogen significantly.2. Different nitrogen levels have significant influence on biomass accumulation of Schisandra chinensis (p<0.05). Biomass aboveground increases as nitrogen level increases. Maximal biomass accumulation arises at 200kg.ha-1 (N4) of nitrogen level provided. After that, biomass accumulation decreases as nitrogen level continue to increase. Change of biomass accumulation underground resembles that aboveground, except the rate is lower. During growth cycle, along with increases of nitrogen level, assimilation products assigned to aboveground also increase. It is best for assimilation products transferred to aboveground at 200kg.ha-1 (N4) of nitrogen level, also best for biomass accumulation.3. During different growth period, different ratios of nitrogen forms have significant influence on total-N, soluble protein and chlorophyll in stems and leaves of Schisandra chinensis. At earlier stage of growth, the indicators decrease as ratio of nitrate nitrogen increase, while they increase at middle and later stage of growth. During the complete growth cycle, nitrates and nitrate reductase activity increase as ratio of nitrate nitrogen increases. At earlier stage of growth (June), different ratios of nitrogen forms have no significant influence on Amax, Q, Rd of Schisandra chinensis seedlings, but have significant influence on Lcp and Lsp. The single form of nitrogen provided decrease dysphotic utilization capacity of Schisandra chinensis, while expands utilization scope of highlight.4. There are significant differences among Schisandra chinensis seedlings at different growth periods absorbing and utilizing different nitrogen forms. Ammonium nitrogen and nitrate nitrogen have significant combined effect on growth of Schisandra chinensis seedlings. At earlier stage, Schisandra chinensis seedlings mainly absorb and assimilate ammonium nitrogen. Biomass aboveground accumulates more as ratio of ammonium nitrogen and nitrate nitrogen is 75:25. While at middle and late stage of growth, Schisandra chinensis seedlings mainly absorb and assimilate nitrate nitrogen. Biomass aboveground accumulates more as ratio of ammonium nitrogen and nitrate nitrogen is 25:75.