Effects of genotype × environment interactions on the morphological and genetic aspects of the seed characteristics of faba beans.

Faba bean (Vicia faba L.) is one of the oldest cultivated crops in the world. It is the third most important feed grain legume globally, after soybean and lupin. It is an autogamous plant with a partial outcrossing rate ranging from 20% to 80%. The objective of most faba bean improvement programs is to enhance yield; however, yield is a complex trait influenced by many other traits. Therefore, in this study, we focused on seed traits that are related to faba bean yield. A set of 110 faba bean genotypes was tested across two different locations (Germany and Egypt) to investigate the effect of genotype-environment interactions and identify single-nucleotide polymorphism (SNPs) related to seed characteristics. This study revealed that there is high genetic variation among genotypes in all traits in each location, and the genotype × location interactions were significant. There was a strong positive correlation among the seed characteristics within each location, but the correlations between the two locations were weak or not significant. FB-231 and FB-227 performed very well in both countries based on the selection index (SI) values, whereas FB-193 and FB-185 had the lowest SI values in both countries. All genotypes were genotyped via single primer enrichment technology, which resulted in 33,165 SNP markers. The association mapping revealed 162 and 31 significant SNPs in seed traits scored in Germany and Egypt, respectively. A set of seven SNPs was associated with more than one seed trait in Germany, whereas only one SNP was associated with two traits in Egypt. No shared markers were found between the two locations for any of the seed traits. These markers represent potential targets for future breeding programs to enhance seed size and understanding of its genetic control in the faba bean.