Screening faba bean (Vicia faba L.) genotypes for resistance to Stemphylium blight in Iran

Improving yield, diseases resistance, abiotic stress tolerance, seed quality and other agronomic traits are the most important aims of faba bean breeding. Stemphylium blight, a fungal disease caused by Stemphylium botryosum and S. vesicarium, causes great devastation in faba bean production in Golestan province. The levels of resistance to Stemphylium blight disease were evaluated in 99 faba bean genotypes. The experiment was conducted during the 2011–2012 cropping season in Gorgan, Iran. The experiment was laid out in randomized complete block design with three replications. Treatment variables studied were disease severity, area under disease progress curve (AUDPC), plant height, yield component and grain yield. Plants which scored for resistance on a 1 to 9 severity scale. The results revealed significant differences between genotypes for all studied traits. There was significant variability for resistance to Stemphylium blight disease among faba bean cultivars. According to Principal Component Analysis (PCA), the first two components explained about 98 % of genetic variation. The PC1 indicated that grain yield and biological yield per plant were important traits for classification. While AUDPC was important in PC2. Based on Cluster analysis, 99 genotypes were divided into three clusters. Cluster II showed maximum grain yield per plant and biological yield harvest index. Diversity in the resistance of faba beans to Stemphylium blight determines their potential for improved efficiency in order providing diseases management in this crop, and crossing nurseries for faba bean improvement.