Nodulation performance and agronomic traits of European common bean (Phaseolus vulgaris L.) genetic resources

Field production of common beans benefit from root microbial associations, although they are generally considered to be weaker nitrogen fixers than other legumes. Therefore, the number of nodules on the roots of 64 accessions of the European common bean (Phaseolus vulgaris L.) and the relationship between the number of nodules per accession and other plant characteristics (growth type, earliness, seed yield, and total nitrogen content in seeds) were studied. The results indicated that growth type and earliness influenced the number of nodules per accession (the contributions of principal component analysis were 34.9% for Dim1 and 29.8% for Dim2). The average number of nodules per accession with indeterminate growth type was almost five times higher (20.1) than for accessions with determinate growth type (4.4). Common bean accessions with regular growth cycle length had the highest number of nodules (21.9). In contrast, nodulation efficiency, measured as seed yield per plant and total nitrogen content in seeds, were not correlated with the number of nodules per accession (correlation analysis, r < 0.1). Consequently, data on the nodulation efficiency of European common bean accessions are important for breeding programmes in conjunction with other agronomically important traits for commercial and/or organic cultivation systems.