The nitrogen fixing ability of common bean (Phaseolus vulgaris L.) in association with rhizobia is often characterized as poor compared to other legumes, and nitrogen fertilizers are commonly used in bean production to achieve high yields, which in general inhibits nitrogen fixation. In addition, plants cannot take up all the nitrogen applied to the soil as a fertilizer leading to runoff and groundwater contamination. The overall objective of this work is to reduce use of nitrogen fertilizer in common bean production. This would be a major advance in profitability for the common bean industry in Canada and would significantly improve the ecological footprint of the crop. In the current work, 22 bean genotypes [including recombinant inbred lines (RILs) from the Mist × Sanilac population and a non-nodulating mutant (R99)] were screened for their capacity to fix atmospheric nitrogen under four nitrogen regimes. The genotypes were evaluated in replicated field trials on N-poor soils over three years for the percent nitrogen derived from atmosphere (%Ndfa), yield, and a number of yield-related traits. Bean genotypes differed for all analyzed traits, and the level of nitrogen significantly affected most of the traits, including %Ndfa and yield in all three years. In contrast, application of rhizobia significantly affected only few traits, and the effect was inconsistent among the years. Nitrogen application reduced symbiotic nitrogen fixation (SNF) to various degrees in different bean genotypes. This variation suggests that SNF in common bean can be improved through breeding and selection for the ability of bean genotypes to fix nitrogen in the presence of reduced fertilizer levels. Moreover, genotypes like RIL_38, RIL_119, and RIL_131, being both high yielding and good nitrogen fixers, have potential for simultaneous improvement of both traits. However, breeding advancement might be slow due to an inconsistent correlation between these traits.

普通豆的固氮能力（菜豆与其他豆科植物相比，与根瘤菌相关联的L.）通常被认为较差，而豆类生产中通常使用氮肥来获得高产，这通常会抑制固氮。此外，植物不能吸收所有作为肥料施用到土壤中的氮，从而导致径流和地下水污染。这项工作的总体目标是减少普通豆生产中氮肥的使用。这将是加拿大普通豆产业盈利能力的重大进步，并将大大改善作物的生态足迹。在当前的工作中，筛选了22种豆基因型[包括来自Mist×Sanilac种群的重组自交系（RIL）和非结瘤突变体（R99）]在四种氮制度下固定大气氮的能力。在三年的N贫瘠土壤上进行的重复田间试验中，对基因型进行了评估，以评估源自大气的氮百分比（％Ndfa），产量和许多与产量相关的性状。大豆的基因型在所有分析的性状上都不同，并且氮水平显着影响了大多数性状，包括三年中的％Ndfa和产量。相反，根瘤菌的施用仅显着影响很少的性状，并且多年来的效果不一致。施氮对不同基因型豆的共生固氮（SNF）有不同程度的影响。这种变化表明普通豆中的SNF可以通过育种和选择降低肥料水平下豆基因型固定氮的能力来提高。此外，基因型如RIL_38，RIL_119和RIL_131，既是高产又是良好的固氮剂，具有同时改良两个性状的潜力。但是，由于这些性状之间的相关性不一致，育种进展可能会很慢。