Evaluation of agronomic performance and drought tolerance indices of diverse barley genotypes under Mediterranean conditions and water stress

Abstract

Drought is an increasing constraint to barley cultivation in the Mediterranean region and thus there is a necessity to find genotypes adapted to maintain stable productivity under water stress. Drought adaptation in seven genotypes of barley (Hordeum vulgare L.), including local populations and modern two- and six-row cultivars, was evaluated under field conditions in Greece over two growing seasons. Four irrigation regimes, ranging from well-watered to severe drought stress, were imposed under permanent rainout shelter in order to evaluate progressive water deficit impact on growth parameters, biomass production, grain yield, yield components, and drought tolerance indices. Under drought stress, a decrease in plant height and tiller number was noted. Total biomass production was also significantly affected by water stress, when the six-row cultivar Elassona showed the largest values of total biomass accumulation under non-stress (21404 and 21425 kg ha-1 in 2013-2014 and 2014-2015, respectively), whereas under severe stress, the six-row population ANP-233/07 and two-row cultivar Grace showed the lowest biomass values in 2013-2014 (10271 kg ha-1) and 2014-2015 (9725 kg ha-1), respectively. Two-row cultivars Cha-Cha and Grace demonstrated better productivity and achieved grain yield values of 7041.5 and 6670.8 kg ha-1 in 2013-2014 and 6504.3 and 6245.8 kg ha-1 in 2014-2015 under well-watered conditions, while having the highest grain yield values under severe stress. Productivity-based drought indices such as Stress Tolerance Index (STI), Mean Productivity (MP), Geometric Mean Productivity (GMP), and Harmonic Mean (HM) appeared efficient in selecting the genotypes combining high productivity and stress tolerance. The local population of six-row barley ANP-233/07 was characterized by higher reproductive stability in terms of grain number under water deficiency. These results emphasize the diversity of drought adaptation strategies within barley genetic resources and suggest promising genotypes for breeding efforts to improve drought resistance in Mediterranean conditions.