白桦幼苗NH+4/NO-3吸收特征的研究
NH+4/NO-3 absorption characteristics of Betula platyphylla seedlings
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摘要: 采用水培方法，研究白桦幼苗氮吸收特征。结果表明：白桦早期对NO-3N呈偏向选择吸收，供氮强度和光强增加使苗木氮吸收总量、NH+4N吸收量、NO-3N吸收量增加。根系是白桦早期还原NO-3的主要部位；根系和叶片硝酸还原酶活性均因供NO-3强度和光强的增加而增强。较低供氮水平下，NH+4优势处理苗木的营养液pH值下降，NO-3优势处理苗木的营养液pH值上升；氮吸收量增大导致NH+4优势处理苗木的营养液pH值下降程度深化，而供NO-3营养液pH值却未因此进一步升高；较高光强下，各处理苗木营养液pH值均有不同程度下降。Abstract: We investigated NH+4/NO-3 absorption characteristics of Betula platyphylla seedlings using solution cultivation. The results showed that the seedlings preferred nitrate over ammonium in their nutrient regime. Absorption capacity of NH+4N, NO-3N and total N increased with the increase of nitrogen application or light intensity. Most of nitrate was reduced in roots; nitrate reductase activity in roots and leaves responded to increased nitrate availability or increased light intensity. Medium pH value decreased in the low Napplication solution of high NH+4/NO-3 ratio, and increased with low NH+4/NO-3 ratio; medium pH value decreased more markedly in the high Napplication solution of high NH+4/NO-3 ratio, but did not increase sharply in NO-3 solution; medium pH value of all the seedlings decreased with increased light intensity.
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Keywords:
- Betula platyphylla seedlings /
- NH+4 /
- NO-3 /
- nitrate reductase /
- pH value
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