Hydroponic growth and the nondestructive assay for dinitrogen fixation.
Hydroponic growth and the nondestructive assay for dinitrogen fixation.
复制标题
水培生长和二氮固定的无损测定。
DOI：
10.1104/pp.68.6.1380
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发表时间：
1981
期刊：
影响因子：
7.4
通讯作者：
E. Ralston
中科院分区：
文献类型：
--
作者：
J. Imsande;E. Ralston
如果要支持植物持续生长，水培生长培养基必须具有良好的缓冲性。尽管1.0毫摩尔磷酸盐通常用作水培生长培养基的缓冲剂，但在该浓度下，它通常对仅从二氮固定获得其氮的大豆植物是有毒的。另一方面，我们表明，1.0至2.0毫摩尔的2-（N-吗啉代）乙磺酸，pK（a）6.1，具有良好的缓冲能力，它既不干扰也不有助于营养大豆植物的生长。此外，它既不妨碍发酵，也不妨碍二氮固定的测定。因此，在补充有1.0至2.0毫摩尔2-（N-吗啉代）乙磺酸和0.1毫摩尔磷酸盐的培养基上水培生长的大豆植物获得优异的生长速率，并且在不存在添加的固定氮的情况下，获得非常高的二氮固定速率。结合水培生长的概念和敏感的乙炔还原技术，我们已经设计了一个简单，快速，可重复的测定程序，从而可以测量由个别植物的固氮率在这些植物的整个生命周期。通过非破坏性乙炔还原法测定的固氮速率与凯氏定氮法测定的植物氮累积速率大致相等。由于程序简单，一名研究人员每天可以轻松地单独分析50株植物。
Hydroponic growth medium must be well buffered if it is to support sustained plant growth. Although 1.0 millimolar phosphate is commonly used as a buffer for hydroponic growth media, at that concentration it is generally toxic to a soybean plant that derives its nitrogen solely from dinitrogen fixation. On the other hand, we show that 1.0 to 2.0 millimolar 2-(N-morpholino)ethanesulfonic acid, pK(a) 6.1, has excellent buffering capacity, and it neither interferes with nor contributes nutritionally to soybean plant growth. Furthermore, it neither impedes nodulation nor the assay of dinitrogen fixation. Hence, soybean plants grown hydroponically on a medium supplemented with 1.0 to 2.0 millimolar 2-(N-morpholino)ethanesulfonic acid and 0.1 millimolar phosphate achieve an excellent rate of growth and, in the absence of added fixed nitrogen, attain a very high rate of dinitrogen fixation. Combining the concept of hydroponic growth and the sensitive acetylene reduction technique, we have devised a simple, rapid, reproducible assay procedure whereby the rate of dinitrogen fixation by individual plants can be measured throughout the lifetime of those plants. The rate of dinitrogen fixation as measured by the nondestructive acetylene reduction procedure is shown to be approximately equal to the rate of total plant nitrogen accumulation as measured by Kjeldahl analysis. Because of the simplicity of the procedure, one investigator can readily assay 50 plants individually per day.