Components of phenotypic variance and heritability of early vigour traits of bread wheat under contrasting water regimes

Exploring drought-tolerance potential and phenotypic plasticity at early stages of development in root system architecture could be crucial in regard to breeding for drought resistance and for selecting wheat ideotypes under climate change conditions. A total of 11 genotypes from the collection of 101 bread wheat genotypes, with desirable traits related to increased drought tolerance, were selected as parents and eight crosses were performed. The genotypes of the P and F1 generations were grown in hydroponic cultivation under polyethylene glycol 6000-induced osmotic stress. The objective of this research was to assess components of phenotypic variance and broad-sense heritability of early vigour traits (nine root and shoot traits) of bread wheat genotypes under induced drought stress compared to the control, in order to choose appropriate traits for breeding for drought resistance. The effect of the genotype on the variability of the tested root traits was higher (46.6%), compared to the tested shoot traits (25.5%), meaning that the root traits can be taken as a more reliable criterion for selection for drought tolerance compared to the investigated shoot traits. Broad-sense heritability was high (> 82%) for most of the tested traits (primary root length, number of seminal roots, total seminal root length, angle of seminal roots, shoot length, the ratio of root dry mass to shoot dry mass), with low genotype ? environment interaction (< 20% of total variation) and breeding for drought tolerance should be focused on these traits.