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在温室内用砂培的方法研究了NO-3 N、NH+4 N及其不同配比对水曲柳 (Fraxinusmandshurica)幼苗生长的影响 .结果表明 ,水曲柳幼苗在营养液NO-3 N NH+4 N为 75 2 5时生长最好 ,营养液中NH+4 N比例继续增加则生长下降 .过量的NH+4 N可抑制水曲柳幼苗根系生长 ,降低幼苗的地下 /地上比 .营养液中NH+4 N比例增加 ,水曲柳幼苗的净光合速率下降 ,体内P浓度增高 ,而Zn和Fe浓度下降 .N素形态明显影响基质的 pH值 ,NO-3 N比例增加使基质 pH值升高 ,NH+4 N比例增加则基质 pH值下降 .完全供给NO-3 N时基质 pH值升至 7 2 2 ,而完全供给NH+4 N时基质的 pH值降至 4 2 0 .
The effects of NO-3 N, NH 4 N and their different proportions on the growth of Fraxinusmandshurica seedlings were studied by means of sand culture in greenhouse. The results showed that in the nutrient solution NO-3 N When NH + 4 N was 75 2 5, the growth was the best, while the NH 4 N ratio in the nutrient solution continued to increase, then the growth decreased. Excessive amount of NH + 4 N could inhibit root growth of Fraxinus mandshurica seedlings and lower the ratio of ground / shoot. The ratio of NH + 4 N in nutrient solution increased, the net photosynthetic rate decreased, the concentration of P in the body increased, but the concentration of Zn and Fe decreased.The morphology of N significantly affected the pH value of the matrix, and the increase of NO- the pH value of the substrate increased and the pH value of the substrate decreased as the proportion of NH + 4 N increased.The pH value of the substrate rose to 722 when NO-3 N was completely supplied and the pH value of the substrate dropped to 4200 when NH + 4 N was completely supplied .