Although nitrate is known to inhibit nodulation and N₂ fixation in symbiotic legumes, little is known about its effect on the uptake and accumulation of trace elements such as Fe, Zn, Mn and Cu. The aim of this study was to evaluate the effect of 5 mM NO₃ ⁻ supply, either with or without rhizobial inoculation, on nodulation, nodule functioning and micronutrient levels in the shoots of soybean (Glycine max L.Merr.), Bambara groundnut (Vigna subterranea L. Vedc) and Kersting’s groundnut (Macrotyloma geocarpum Harm). The results showed reduction in plant growth, nodule formation and nodule dry matter by the supply of 5 mM NO₃ ⁻ to inoculated seedlings of all three species. Nitrate inhibition respectively caused 1.2, 1.4, and 1.5-fold decrease in nodule number per plant in Bambara groundnut, soybean and Kersting’s bean, which resulted in 2.3, 3.3 and 4.5-fold reduction in nodule dry weight of the test species (in that order). The application of 5 mM NO₃ ⁻ to soybean plants also resulted in 2.5, 4.0 and 5.4-fold decrease in shoot accumulation of Fe, Zn and Mn, respectively, when compared to the purely symbiotic control plants. Furthermore, we observed 1.3, 1.8 and 1.3-fold decreases in the concentration of Zn, Mn and Cu in shoots of inoculated Bambara groundnut with NO₃ ⁻ supply, levels lower than those found in soybean. With Kersting’s groundnut, shoot concentration of Fe, Zn and Cu were higher with the application of 5 mM NO₃ ⁻ to inoculated plants when compared to the purely symbiotic treatment, which was opposite to soybean. But pure NO₃ ⁻feeding of this species respectively resulted in 2.0, 1.4 and 1.3-fold decreases in Fe, Zn and Cu relative to inoculated NO₃ ⁻-fed plants. Clearly, NO₃ ⁻ supply to landraces/genotypes of the three legume species did not only inhibit nodule formation and functioning, it also reduced shoot micronutrient levels in soybean and Bambara groundnut, but not Kersting’s bean.

中文翻译：

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硝酸盐对N2固定的抑制作用及其对大豆（Glycine max L. Merr。），Bambara花生（Vigna subterranea L. Vedc）和Kersting花生（Macrotyloma geocarpum Harms。）的芽中微量营养素累积的影响。

尽管已知硝酸盐可抑制共生豆科植物中的根瘤和N ₂固定，但对其对诸如Fe，Zn，Mn和Cu等微量元素的吸收和积累的影响知之甚少。本研究的目的是评价5mM的NO的效果₃ ^-供应，具有或不接种根瘤菌，结瘤上，根瘤运作和微量营养素水平在大豆的芽（大豆L.Merr。），花生巴拉（Vigna subterranea L. Vedc）和Kersting的花生（Macrotyloma geocarpum Harm）。结果由5mM的NO的供给表现出植物生长，结节形成和结节干物质还原₃ ^-接种所有三种树苗。硝酸盐的抑制作用分别使班巴拉花生，大豆和克星廷豆的单株根瘤数减少了1.2倍，1.4倍和1.5倍，从而使测试物种的根瘤干重减少了2.3倍，3.3倍和4.5倍（按此顺序） ）。5mM的NO的应用₃ ^-至大豆植物也导致铁，锌和锰的拍摄积累2.5，4.0和5.4倍的下降，分别比纯粹共生对照植物时。此外，我们观察到1.3，1.8和1.3倍减少在锌，锰和铜的浓度接种花生巴拉的枝条与NO ₃ ^-供应，水平低于大豆。与Kersting的花生油，铁，锌和铜的拍摄浓度分别用5mM NO的应用更高的₃ ^-比纯粹共生治疗，这是相反的大豆时接种的植物。但纯NO ₃ ^-这一物种的供给分别导致在铁，锌和铜的相对2.0，1.4和1.3倍降低到接种NO ₃ ^-喂食的植物。显然，NO ₃ ^-供应地方品种/大豆和花生班巴拉文，但不Kersting的豆三个豆类品种的基因型做不仅抑制结节的形成和运作，这也降低了拍摄微量营养素水平。