Leaf-atmosphere NH(3) exchange of white clover (Trifolium repens L.) in relation to mineral N nutrition and symbiotic N(2) fixation.
Leaf-atmosphere NH(3) exchange of white clover (Trifolium repens L.) in relation to mineral N nutrition and symbiotic N(2) fixation.
复制标题
白三叶草（Trifolium repens L.）叶-大气 NH(3) 交换与矿物质 N 营养和共生 N(2) 固定的关系。
DOI：
10.1093/jxb/53.366.139
复制
发表时间：
2002
影响因子：
6.9
通讯作者：
J. Schjoerring
中科院分区：
文献类型：
--
作者：
B. Herrmann;M. Mattsson;J. Fuhrer;J. Schjoerring
研究了白三叶的植物-大气NH(3)交换。在含有0(N(2)基)、0.5(低N)或4.5(高N)mm NO(3)(-)的营养液中生长。研究的目的是表明NH(3)交换潜力是否受N(2)固定相对于NO(3)(-)供应的比例的影响。在处理过程中，NO(3)(-)抑制固氮后，原位测定总固氮酶活性(TNA)，并根据质外体NH4(+)浓度([NH4(+)])和pH计算气孔NH(3)补偿点(chi(NH(3)。用可控试管系统连续记录全株NH(3)交换、蒸腾作用和净CO(2)交换。虽然地上部全N浓度随着矿质氮肥施用量的增加而增加，但组织和质外体[NH_4(+)]以及CHI(NH_3)在三个处理中都是相同的。在无NH(3)的空气中，无论是高N植物还是N(2)植物，都观察到了~lt；1nmolm(-2)S(-1)的净NH(3)排放速率。当向植物供应含有40nmolmol(-1)NH(3)的空气时，只通过共生N(2)固定获得N的植物比种植NO(3)(-)的植物对NH(3)的净吸收更高。结果表明，无论有无NO(3)(-)，白三叶的共生N(2)固定和矿质N的吸收相对于NH4(+)池是平衡的，导致CHI(NH(3))相等。当大气NH(3)浓度超过CHI(NH(3))时，NH(3)的吸收速率受植物氮素需求的控制。
Plant-atmosphere NH(3) exchange was studied in white clover (Trifolium repens L. cv. Seminole) growing in nutrient solution containing 0 (N(2) based), 0.5 (low N) or 4.5 (high N) mM NO(3)(-). The aim was to show whether the NH(3) exchange potential is influenced by the proportion of N(2) fixation relative to NO(3)(-) supply. During the treatment, inhibition of N(2) fixation by NO(3)(-) was followed by in situ determination of total nitrogenase activity (TNA), and stomatal NH(3) compensation points (chi(NH(3))) were calculated on the basis of apoplastic NH4(+) concentration ([NH4(+)]) and pH. Whole-plant NH(3) exchange, transpiration and net CO(2) exchange were continuously recorded with a controlled cuvette system. Although shoot total N concentration increased with the level of mineral N application, tissue and apoplastic [NH4(+)] as well as chi(NH(3)) were equal in the three treatments. In NH(3)-free air, net NH(3) emission rates of <1 nmol m(-2) s(-1) were observed in both high-N and N(2)-based plants. When plants were supplied with air containing 40 nmol mol(-1) NH(3), the resulting net NH(3) uptake was higher in plants which acquired N exclusively from symbiotic N(2) fixation, compared to NO(3)(-) grown plants. The results indicate that symbiotic N(2) fixation and mineral N acquisition in white clover are balanced with respect to the NH4(+) pool leading to equal chi(NH(3)) in plants growing with or without NO(3)(-). At atmospheric NH(3) concentrations exceeding chi(NH(3)), the NH(3) uptake rate is controlled by the N demand of the plants.