Heterotic effects and inbreeding depression in F1 and F2 populations of wheat

Wheat breeding has delivered huge benefits, especially over a century with increased productivity and stability in yield even after facing the inevitable stresses. The present study aimed to determine the genetic potential, heterotic effects, and inbreeding depression in F 1 and F 2 populations, respectively for earliness and yield traits in wheat. The crosses were made in 2017-18 through line by tester mating design with seven lines i.e., Seher-06, Pirsabak-85, Shahkar-13, Galaxy-13, Ghaznavi-98, TD-1, and Inqalab-91, and three testers i.e., Parula, Yr-5 and Yr-10, at the Cereal Crop Research Institute (CCRI), Nowshera, Pakistan. For getting wheat F 2 populations, the generation was also advanced during the summer season of 2018 at the Summer Agricultural Research Station (SARS), Kaghan, Pakistan. After advancing the generation, 21 F 1 and 21 F 2 wheat populations with their ten parental genotypes were grown during crop season 2018-2019 in a randomized complete block design with three replications at the University of Agriculture, Peshawar, Pakistan. Analysis of variance exhibited significant differences among the total genotypes, parental genotypes, lines, testers, crosses, and line by tester interactions for the majority of the traits in F 1 and F 2 generations. Results further revealed that the F 1 hybrid Galaxy-13 × Yr-10 showed the maximum grain yield per plant (55.08 g), followed by F 1 hybrids Shahkar-13 × Parula (45.66 g) and Shahkar-13 × Yr-5 (45.41 g). For grain yield per plant, significant positive mid-parent heterosis was recorded in 10 hybrids, ranging from 17.37% (Seher-06 × Parula) to 208.30% (Galaxy-13 × Yr-10). Significant better parent heterotic effects were recorded in F 1 hybrids i.e., Galaxy-13 × Yr-10 (127.35%), Ghaznavi-98 × Yr-10 (74.37%), Galaxy-13 × Parula (41.34%), TD-1 × Parula (37.42%), Galaxy-13 × Yr-5 (35.68%) for grain yield per plant. Significant economic heterosis was recorded among the eight hybrids for grain yield, ranging from 4.20% (Ghaznavi-98 × Yr-5) to 73.05% (Galaxy-13 × Yr-10). In the case of inbreeding depression, significant ( p ≤0.01) negative values were recorded in 12 F 2 populations ranging from -48.72% (Shahkar-13 × Parula) to -6.82% (TD-1 × Parula) grain yield per plant.