A 7×7 diallel cross in barley for developing high yielding and saline tolerant barley (Hordeum vulgare L.)

Abstract

In this experiment, F1s produced from a 7×7 half-diallel cross along with their parents were evaluated to develop high yielding and saline-tolerant barley lines. The investigation focused on the general combining ability (GCA) of parents, specific combining ability (SCA) of offspring, genetic action, and heterosis of eight quantitative variables. Genetic analysis and potence ratio suggested that different degrees of dominance controlling the inheritance of the studied traits. Significant GCA and SCA variances suggested the presence of both additive and non-additive gene actions controlling the traits. However, a GCA:SCA ratio lower than 1 indicated the preponderance of the non-additive gene action involved in the expression of the traits. The parents P5 and P6 possess the genetic potential favorable for early and short stature in their F1s. Conversely, P2 and P4 were more likely to produce short F1s with high yield potential. Based on the mean performance, SCA, and heterobeltiosis, crosses P2×P3, P2×P7, P3×P4, P4×P5, P5×P6 and P6×P7 were selected as promising F1s for earliness, short stature, and high yield potency. These crosses are recommended for further breeding to obtain early-maturing and high-yielding segregants. To identify saline-tolerant F1s, screening was conducted in saline media prepared in half strength Hoagland solution. The salinity stress involved exposing F1s to 100 mM NaCl for first 10 days, and followed by an increase to 150 mM until maturity. Among the F1s, five crosses (P1×P2, P2×P3, P3×P5, P4×P6 and P4×P7) exhibited promising signs of saline tolerance based on a comprehensive evaluation of healthy seed set, K+/Na+ ratio, root volume, generation of reactive oxygen species (O2•− and H2O2), and activities of key antioxidant enzymes like superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), ascorbate peroxidase (APX) and glutathione reductase (GR). These crosses will undergo further evaluation in the next filial generation to confirm heritable saline tolerance.