Yield component variations in a set of recombinant inbred lines of durum wheat grown in drought environments

Improvement of grain yield has been the principal goal of several wheat breeding programs in the Mediterranean region. The objectives of the present work were to analyse phenotypic and genetic variation for grain yield and yield components in a durum wheat recombinant inbred line population grown under water-limited conditions, and to estimate heritability and genetic advances for yield components in different moisture regimes. Field experiments were carried out at two locations in Southern Italy under rainfed and nonstress treatments. Genotype x environment interactions were detected for yield components. Transgressive variation was found in both treatments. In the segregant population, the heritability values for grain yield and related traits were similar under rainfed and nonstress treatments, and this suggested that the wheat growing period in Southern Italy environments are characterised by moderate water stress. Genetic advance for grain yield was 4.38% and 2.94% in the rainfed and nonstress treatments, respectively. Taking into account that the mean values of grain yield in the segregant population across locations were 3.29 t/ha and 4.23 t/ha in the rainfed and nonstress conditions respectively, the absolute gain from selection for grain yield was similar in both water-conditions. These data indicated that the gain from selection for grain yield were similar in both water conditions.