Abstract:
Barley (Hordeum vulgare L.) is a major food crop in Ethiopia. A high inter-annual rainfall variability,
concomitant variable planting dates and unpredictable drought stress at any time during the rainy
season are severe constraints to barley production in Ethiopia. To study genotype by environment (G x
E) interactions and grain yield stability, 18 barley genotypes (three landraces and 15 improved cultivars)
were evaluated for yield and flowering time in two locations (Ambo and Jimma) and four staggered
sowing dates over two years (2012-2013) giving a total of 16 environments. It was observed a wide
phenotypic variation over environments for both grain yield (677-2,944 kg ha-1
) and days to 50%
flowering (63-82 days). Considering the 18 genotypes and 16 environments, both genotype (G) and G x
E interaction variance components were highly significant for grain yield, with a ratio of approximately
1:1. The G x E analysis revealed that the first two interaction principal component axes (IPCA1 and
IPC2) in an additive main effect and multiplicative interaction (AMMI) model explained 66.1% of the total
G x E interaction for grain yield (P < 0.001). Of the 16 environments, 12 grouped into two clusters which
largely corresponded to test locations. The tested genotypes revealed a wide variation for both static
and dynamic yield stability measures. Compared to improved cultivars, farmers' landraces displayed
higher average static stability (e.g. IPCA1; P = 0.017) and similar superiority indices (dynamic stability).
These landraces are therefore a source of germplasm for breeding resilient barley cultivars. Staggered
planting proved to be a useful method for evaluating genotype stability across environmental factors
beyond location and season.
