Genetic gains in Nordic spring barley breeding over sixty years

Accurate assessments of genetic gains ensuing from plant breeding for the most important agronomic characteristics in Nordic spring barley (Hordeum vulgare L.) are not available. Hence this research was aimed to determine the rate of genetic improvement in the Nordic barley breeding pool. This study included 90, 2-row spring barley cultivars released (1942-1988) and 29, 6-row spring barley cultivars released (1930-1991) adopted by Nordic farmers that were tested in four Nordic locations for three consecutive years. Relative genetic gain owing to plant breeding was 13% in 2-row barley and 34% in 6-row barley for grain yield. The absolute gain for this characteristic was 13 +/- 3 kg ha(-1) year (-1) in 2-row barley, and 22 +/- 3 kg ha(-1) year(-1) in 6-row barley. Improved yield was achieved in Nordic barley by reducing plant height (0.20 +/- 0.04 cm year(-1) for 2-row barley and 0.16 +/- 0.06 cm year(-1) for 6-row cultivars), thereby reducing significantly lodging (0.5 +/- 0.1% year(-1) and 0.4 +/- 0.1 year(-1)), and increasing significantly the harvest index (0.0008 +/- 0.0002 year(-1) and 0.0018 +/- 0.0002 year(-1)). Additionally, in 2-row spring barley cultivars resistance to powdery mildew (0.19 +/- 0.08% year(-1)) and thousand-kernel weight (0.07 +/- 0.03 g year(-1)) were also significantly enhanced, whereas hectoliter weight was improved (0.06 +/- 0.02 kg year(-1)) in 6-row barley cultivars in the period investigated.