Heritability estimates of spot blotch resistance and its association with other traits in spring wheat crosses

Summary Spot blotch caused by Cochliobolus sativusis considered a major disease problem of wheat(Triticum aestivumL.) in the warm areas of South Asia. This study estimated heritability (h ²) of resistance to spot blotch and its correlation with days to heading DH) and maturity (DM), one-hundred-kernel weight (HKW), and plant height (PHT) in 14 crosses involving four resistant (‘Attila’, ‘Chirya 7’, ‘G 162’, and ‘SW89.5422’) and two susceptible (‘Sonalika’ and ‘HD2329’) wheat genotypes. Data were recorded on F₅and F₆lines in fields under natural epidemics of spot blotch in 2003 and 2004, respectively. Heritability was estimated for area under disease progress curve (AUDPC), AUDPC/day, and the highest disease score (HDS) using offspring-parent regression (h _op ²) and realized heritability (h ² _R) procedures. Heritability estimates were low to high in terms of AUDPC (0.21 < h _op ²< 0.64; 0.32 < h _R ²< 0.70), AUDPC/day (0.40 < h _op ²< 0.96; 0.42 < h _R ²< 0.99), and HDS (0.29 < h _op ²< 0.92; 0.32 < h _R ²< 0.95). The h ²estimates for AUDPC/day were higher than for AUDPC and HDS. Estimates of h _R ²were by and large higher than h _op ²in the same cross. A weak negative or nonsignificant correlation of spot blotch score with HKW, DH, DM, and PHT indicated that independent selection for resistance and these agronomic traits is possible.