Heritability Estimates and Response to Selection for Fusarium Head Blight Resistance in Soft Red Winter Wheat

Abstract

Fusarium head blight (FHB), caused by Fusarium graminearum (Schwabe), is an economically important disease of wheat (Triticum aestivum L.). After epidemics in the USA during the 1990s, a resistance‐breeding effort was undertaken focusing initially on the transfer of Type II resistance from unadapted Chinese cultivars. The objective of this study was to determine the magnitude and heritability of resistance in populations derived from adapted parents. Three soft red winter (SRW) wheat populations of 40 families each were artificially inoculated with Fusarium graminearum under mist irrigation in 2003 and 2004 at Lexington and Princeton, KY. Traits measured included anthesis date, plant height, disease severity, Fusarium‐damaged kernels (FDK) and deoxynivalenol (DON) concentration. Broad sense heritability (BSH) estimates were generated from entry means over the four environments. Heritability of severity was approximately 0.30 in all populations; heritability of FDK ranged from 0.16 to 0.20. In 2003, a selection intensity of 20% was imposed on all populations, and the eight lowest severity families were advanced and evaluated at Lexington and Princeton in 2004. Direct selection response, averaged over both locations, ranged from 1.9 to 4.1% reduction in severity. Correlated reduction in FDK ranged from 0.4 to 6.5%; there was also a correlated increase in plant height of 1.7 to 4.1 cm after one cycle of selection. Progress in FHB resistance breeding in the absence of major QTL is likely to be constrained by low heritability and genotype × environment (G × E) interaction.