ASSIMILATION OF NITRATE AND AMMONIUM BY THE SCOTS PINE (PINUS-SYLVESTRIS) SEEDLING UNDER CONDITIONS OF HIGH NITROGEN SUPPLY
ASSIMILATION OF NITRATE AND AMMONIUM BY THE SCOTS PINE (PINUS-SYLVESTRIS) SEEDLING UNDER CONDITIONS OF HIGH NITROGEN SUPPLY
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DOI：
10.1111/j.1399-3054.1992.tb04706.x
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发表时间：
1992-04-01
影响因子：
6.4
通讯作者：
MOHR, H
中科院分区：
文献类型：
--
作者：
FLAIG, H;MOHR, H
樟子松苗木的研究在控制条件下，在珍珠岩上生长21d。除水分对照外，还采用硝酸钾(15 Mm)、(NH4)2SO4(7.5 mm)和硝酸铵(15 Mm)处理，研究了高供氮对氮素同化的影响。在一些实验中，在碱性铵溶液中加入1.3 mM的钾。在标记研究中，硝酸盐和铵是2.3原子%的N-15富集物。研究发现，在21天的时间里，土壤对氨氮的吸收大约是硝态氮的三倍。然而，同时施用的硝酸盐和铵的吸收程度与单独施用的程度相同(相加性)。培养基中K+的存在不影响N的吸收。在可溶性含氮化合物中，对硝酸盐、铵和8种氨基酸进行了定量。研究发现，在ALT条件下，硝酸盐的同化作用可以与NO3-的吸收相适应。游离硝酸盐、氨氮或氨基酸的积累量均未超过水培苗的值。另一方面，在高铵供应的情况下，吸收的氮远远多于结合到不可溶含氮物质(蛋白质)中的氮。其余的氮积累在中间储存池(游离NH4+谷氨酰胺、天冬氨酸、精氨酸)。当营养液中提供钾素时，这些积累的氮中的一部分可以并入蛋白质中。因此，钾不仅是作物蛋白质合成的必需元素，在针叶树中也是如此。
Seedlings of Scots pine (Pinus sylvestris L.) were grown on perlite for 21 days under controlled conditions. Apart from the water control, KNO3 (15 mM), (NH4)2SO4(7.5 mM), and NH4NO3 (15 mM) were offered to study the effects of a high nitrogen supply on nitrogen assimilation. In some experiments 1.3 mM potassium was added to the basic ammonium solutions. In labelling studies nitrate and ammonium were 2.3 atom% N-15-enriched. It was found that over the 21-day period approximately three times more ammonium-N was taken up than nitrate-N. However, nitrate and ammonium, applied simultaneously, were taken up to the same extent as if they were applied separately (additivity). The presence of K+ in the medium did not affect N-uptake. Among the soluble N-containing compounds nitrate, ammonium and 8 amino acids were quantified. It was found that assimilation of nitrate can cope with the uptake of NO3- under alt circumstances. Neither free nitrate nor ammonium or amino acids accumulated to an extent exceeding the values of water-grown seedlings. On the other hand, in case of high ammonium supply considerably more nitrogen was taken up than could be incorporated into nonsoluble N-containing substance ('protein'). The remaining nitrogen was found to accumulate in intermediary storage pools (free NH4+ glutamine, asparagine, arginine). Part of this accumulated N could be incorporated into protein when potassium was offered in the nutrient solution. It is concluded that potassium is a requirement for a high rate of protein synthesis not only in crop plants but also in conifers.