Selection for yield and earliness in mutated genotypes of spring barley (Hordeum vulgare) in cool and short-season environments

This research was carried out in a high altitude, cool and short-season environment in the years 2004 and 2005. In this research, the 2-rowed spring barley (Hordeum vulgare) cultivar 'Tokak 157/37' and 18 artificial mutated lines obtained from this cultivar by gamma irradiation were used. The durations for the vegetative period, grain-filling period, and maturity period and their associated growing degree-days (GDD) were studied. The relationships between these phenological growth traits and grain yield were determined and the desirable genotypes which were both early maturing and high yielding were identified. Grain yield was generally higher in the genotypes which had a short-maturity period and fewer associated GDD, and therefore, negative relationships between grain yield and the phenological growth traits were observed. ML 17 and ML 19 mutated genotypes were found to be both early maturing and high yielding whereas ML 4, ML 12, ML 16, ML 32, ML 34, and ML 36 were only high yielding when compared with the standard cultivar. In environments with cool and limited growing seasons, such early maturing and high yielding genotypes provide the most promising materials from which to develop new cultivars of spring barley.