Effect of row type, flowering type and several other spike characters on resistance to Fusarium head blight in barley

Fusarium head blight (FHB) is a destructive disease of barley. The genetics and expression of resistance to FHB in barley is complex, and various spike characters are thought to possibly influence resistance. Tests using spray-inoculation of Fusarium graminearum at anthesis in greenhouse environments showed that two-rowed and cleistogamous varieties from Japan belong to the highest resistance group, while six-rowed and chasmogamous varieties are mostly susceptible. In order to evaluate the effect of such spike characters, including row type and flowering type, on FHB resistance, near-isogenic lines (NILs) differing in these characters were tested for their resistance. Two testing methods were used: the 'pot-plant' and 'cut-spike' methods, in which spikes at anthesis were spray-inoculated in greenhouse environments. The chasmogamous NILs and some six-rowed NILs were significantly more diseased than cleistogamous and two-rowed parent lines, respectively, and the difference in FHB severity was greater and more stable between cleistogamous/chasmogamous NIL pairs than between two-/six-rowed pairs. Slight or no differences were observed in glaucous/non-glaucous, normal/dense spike, normal/uzu type and normal/deficiens NIL pairs. The results indicate that the contribution of cleistogamy and/or the genetic background toward FHB resistance is more than that of row type and the other tested spike characters. Further, it should be possible to develop six-rowed varieties with FHB resistance nearly as good as that of the two-rowed varieties.