Inheritance of resistance to Fusarium Head Blight in four populations of barley

Fusarium Head Blight (FHB), caused by Fusarium graminearum Schwabe [(teleomorph Giberella Zeae (Schwein.)], has been a major disease problem of barley (Hordeam vulgare L.) in the U.S. Midwest since 1993. It can make a potentially profitable barley crop unusable for malting, and substantially reduce its value as a feed grain. The main cause of economic loss in malting barley is the presence of deoxynivalenol (DON) or vomitoxin, a mycotoxin produced by the fungus. The objective of this research was to investigate the inheritance of resistance to FHB by the estimation of heritability through components of variance in multiple environments. Four populations resulting from crosses between putative resistant and susceptible parents were evaluated in inoculated and mist irrigated nurseries at three locations in Minnesota from 1995 to 1997 and China in 1997. On the basis of multiple environment data, estimates of heritability for FHB ranged from 0.48 to 0.76. Heritability estimates from individual environments for FHB ranged from low to high; these estimates were likely inflated by genotype X environment (G X E) interaction. Resistance levels approximating that of the resistant parent were recovered in most populations and one transgressive resistant line was found in Population 3. Transgressive segregates toward susceptibility were found in Populations 2, 3, and 4 for FHB. The heritability estimates were somewhat encouraging, as they indicated that moderate genetic gain can be expected when selecting for FHB resistance in a breeding program. However, a strong message was conveyed in the variable response of the parents and the ever present G X E interaction that FHB resistance breeding represents an unusually large challenge.