Evaluation of Resistance to Leaf Spot Diseases and Yield Characteristics in Faba Bean Genotypes through Cluster Analysis and Genotype by Trait Biplot

Faba bean (Vicia faba L.) is one of the most important multi-purpose legumes with a wide range of adaptation, high nutritional value, medicinal effect and biological nitrogen fixation. In recent years, the area under Faba bean cultivation has declined due to the spread of diseases and other tensions, increasing production will be possible by introducing cultivars resistant to biological and abiotic stresses.

To access the field resistance of 64 Faba bean genotype to fungal diseases and select suitable genotypes, genotypes were evaluated for disease severity in the field, based on simple lattice design (8 × 8) with two replications in both Gorgan and Dezful research stations in the 2015-2016 cropping season. To calculate the area under the disease progress curve (AUDPC), sampling was done in five steps from the occurrence of leaf spot diseases. Combined analysis of variance and correlation analysis was performed for 10 physiological, morphological, phenological traits and diseases severity. also conducted two graphical multipurpose selection procedures GT biplot in combination with cluster analysis for simultaneous improvement of quantitative traits and disease resistance in two environment. Clustering of genotypes and traits traits separately in each experiment using Ward method and Square Euclidean Distance were performed and the corresponding heatmap was plotted using metaboanalyst 3.0 software.

Based on combined analysis of variance, highly significant differences (P ≤ 0.01) were observed among the faba bean genotypes for agronomic traits and diseases resistance. Number of grains in pod and 100sw indicated positive and significant correlation with yield among of traits. Based on Heatmap graphical mapping assigned the faba bean genotypes into three and four groups in Gorgan and Dezful, respectively. The different groups obtained can be useful for deriving the genotypes with diverse features and diversifying the heterotic pools. The biplot vector view indicates that there was a strong positive association between Number of seed per Pod, 100sw and Plant Height with seed yield in two conditions. Correlation analysis confirmed these results. It seems that Number of seed per Pod, 100sw and Plant Height traits can be used as selection criterion for improving of seed yield in faba bean. Results of the GT biplot in the present study indicated that G52, G56 and G48 genotypes were identified as superior genotypes in Gorgan, and G47, G51 and G56 were identified as superior genotypes in Dezful.

Several genotypes were selected for potential use as parents, The G48 genotype were recognized as superior genotypes regarding yield and traits related to yield and Ascot cultivar can be considered as resistance resource to chocolate spot for faba bean breeding program. G47, G51, G52, G55, G56 and G58 genotypes were chosen for further cultivar release consideration.