Exploitation of yield stability in barley.

KEY MESSAGE: Analyses of registration trials of winter barley suggested that yield and yield stability can be enhanced by developing hybrid instead of line varieties. Yield stability is central to cope with the expected increased frequency of extreme weather conditions. The objectives of our study were to (1) examine the dimensioning of field trials needed to precisely portray yield stability of individual winter barley (Hordeum vulgare L.) genotypes, (2) compare grain yield performance and yield stability of two-rowed lines with those of six-rowed lines and hybrids, and (3) investigate the association of various agronomic traits with yield stability. Static and dynamic yield stability as well as grain yield performance was determined in five series of 3-year registration trials of winter barley in Germany. Each series included 4 or 5 six-rowed hybrids, 40-46 six-rowed inbred lines, as well as 42-49 two-rowed inbred lines. The genotypes were evaluated in 10-45 environments, i.e. year-by-location combinations. We found that precise assessment of yield stability of individual genotypes requires phenotyping in at least 40 test environments. Therefore, selection for yield stability is not usually feasible since the required number of test environments exceeds the common capacity of barley breeding programs. Also, indirect improvement of yield stability by means of agronomic traits seemed not possible since there was no constant association of any agronomic trait with yield stability. We found that compared with line varieties, hybrids showed on average higher grain yield performance combined with high dynamic yield stability. In conclusion, breeding hybrid instead of line varieties may be a promising way to develop high yielding and yield stable varieties.