Breeding of two-rowed naked barley varieties with BaYMV resistance

Six-rowed, naked barley varieties, which are grown in western Japan, are generally susceptible to scab and excess soil moisture injury. For hulled varieties, two-rowed varieties are more tolerant to these injuries than six-rowed varieties are. Therefore two-rowed, naked varieties with good agronomic characters and BaYMV resistance, named YNH-2 and YNH-3, were developed through backcrossings. An intermediate parent, Hakei N107, was developed from the cross of Hiproly/2*Saikai kawa 12//Daisen Gold. Another intermediate parent, NHS-1, was developed from the cross of Hakei N107/Hakei P20. YNH-5 was developed from the cross of Daikei R2264/NHS-1. BaYMV resistance was derived from Daikei R2264, and YNH-3 had nearly the same pedigree as YNH-2. The grain yield of YNH-2 and YNH-3 was same as two-rowed, hulled check varieties. Grain quality was good. At present, two-rowed naked varieties are not grown in Japan, but YNH-2 and YNI-H-3 would contribute a more stable production of naked barley. The cold tolerance of YNH-2 and YNH-3 was moderate, indicating that nakedness and lack of cold tolerance were not always associated, as previously mentioned.