Genetic analysis of winter hardiness and effect of sowing date on yield traits in winter faba bean

- Artificial frost test is very useful for selecting winter hardy genotypes in winter faba bean.
- Late sowing date may protect plants from frost stress but it could be disadvantage for improving yield and its traits.
- One QTL associated with increased winter survival and decreased symptoms of frost on leaves was validated.
- The high genetic diversity found among tolerant genotypes which could be utilized to improve frost tolerance in winter faba bean.

Faba bean is an important grain legume crop that provides nitrogen input into temperate agriculture systems. Breeding for improving winter hardiness and frost tolerance of winter faba bean is currently needed. The main objectives of this study were to examine the winter hardiness and effect of sowing dates (20th October and 20th November of 2012) in a set of 20 genotypes (10 tolerant and 10 susceptible), selected from artificial frost stress experiments, under field conditions and to test the genetic diversity and validate some SNP associated with frost tolerance in the elite genotypes. The genotypes were selected, based on their regrowth after frost (REG, frost tolerance), from 189 winter faba bean genotypes evaluated in Frost Growth Chamber (FGCh). Two winter hardiness traits (winter survival rate and leaf frost susceptibility) and four yield traits (plant height, the number of pods, 100-seed weight, and days to maturity) were scored in this study. All frost-tolerant genotypes showed higher winter survival rate (85%) than the frost-susceptible group (67%) in the first sowing date, while, all genotypes survived in the second sowing date.. The effect of sowing date was not significant for only 100-seed weight. The genetic distance (GD) between genotypes was calculated using 189 single nucleotide polymorphism (SNPs). The GD ranged from 0.59 to 0.89, indicating that a high genetic diversity resided among genotypes. The results suggest that the first sowing date is better for high agronomic features, and selection should be performed to increase winter hardiness in winter faba bean genotypes. Among all SNPs tested in this study, one SNP was validated and found to be associated with increased winter survival rate and decreased leaf frost susceptibility.