Phenotypic plasticity of yield and related traits in rainfed durum wheat

Rainfall and temperature are unpredictable in Mediterranean environments, which results in inconsistent environmental conditions for crop growth and a critical source of uncertainty for farmers and growers. The objectives of the present study were to: (i) quantify and compare the plasticity of durum breeding lines, a modern cultivar and landraces on the basis of yield and agronomic traits and (ii) study associations between plasticity of yield and plasticity of agronomic and phenological traits. Plasticity was quantified using linear models for 11 durum breeding lines, one modern cultivar and two landraces grown in 21 diversified environments. The results showed that the effects due to environment, genotype and genotype x environment (G x E) interaction were significant, which indicates the existence of differences among genotypes for plasticity. Yield ranged from 1939 to 2419 kg/ha across environments and the range of plasticity was 0.66-1.13. The breeding lines and the modern cultivar had higher grain yields compared with the landraces at the same level of plasticity. The landraces with below-average plasticity in yield were characterized as tall in stature and late in heading and maturity, whereas the breeding lines and modern cultivar with above-average plasticity in yield were early in heading and maturity, semi-dwarf and high-yielding, which indicates the success in breeding the materials for unpredictable environmental conditions. In conclusion, yield plasticity was associated with yield improvement and high yield plasticity tends to associate with earliness, shorter plants and low grain weight.