氮、磷处理对落叶松幼苗氮素积累和转运的影响

在温室中采用砂培培养法对落叶松幼苗进行处理。在实验初期和末期分别测定了落叶松幼苗根、茎、叶中氮的浓度,并分别计算了落叶松幼苗的根、茎、叶的氮转运量、转运效率、转运贡献率和氮收获指数。研究结果表明:在不同浓度氮素处理水平下,根的氮转运量、转运效率和氮转运贡献率最高,茎次之,叶最低,并均随供氮水平的提高而增加。在磷处理水平为0.5mmol/L时,根、茎的氮转运量、转运效率和氮转运贡献率最高,但在低于或高于该处理值时相关指标降低;叶的氮转运量和转运效率同样也在供磷水平为0.5mmol/L时最高,在高于或低于上述供磷水平时,均可导致相关指标降低,但其氮转运贡献率在供氮水平为1mmol/L时最高。从氮收获指数看,叶最高、根次之、茎最低,叶的氮收获指数随氮和磷处理水平的升高而升高,而根却降低,茎的反应不显著。

Effects of Nitrogen and Phosphorus Supply on Accumulation and Translocation in Larch seedlings

An experiment was conducted to study the effects of nitrogen (N) and phosphorus (P) supply on accumulation and translocation in larch seedlings in greenhouse with sand culture from April to September. On April 10, one-year-old larch seedlings, after their roots washed and sterilized, were transplanted into a plastic pot containing sterilized and washed sand, and supplied with complete nutrient solution. On May 22, the seedlings were treated with five different N concentrations (1, 2, 4, 8 and 16 mmol/L, respectively) and five different P concentrations (0.125, 0.250, 0.500, 1.000 and 2.000 mmol/L, respectively). After five and fifteen weeks of treatment, the roots, shoots and needles of larch were collected and N contents were determined. N translocation amount, N translocation efficiency, N contribution, N harvest index were calculated. Results indicate that roots have the highest N translocation amount, N translocation efficiency and N contribution, and then followed by shoots and needles in order under different nitrogen levels, and all rise with the increase of N supply. The N translocation amount, N translocation efficiency and N contribution in roots and shoots are the highest with 0.5 mmol/L P supply, and the same is true of the translocation amount and N translocation efficiency in needles. However, the N contribution in needles is the highest with 1.0 mmol/L P supply, and the related values above all decline with increasing or decreasing P supply. The N harvest index of needles is the highest, and then followed by roots and shoots in order. The N harvest index of needles increases with increasing P supply, while that of the roots decline, however the effect on shoots is insignificant.