Enhancing drought resilience in durum wheat: effect of root architecture and genotypic performance in semi-arid...

Developing drought-adapted genotypes is a primary goal for achieving resilient agriculture in the Mediterranean region. Durum wheat, a widely grown crop in the drylands of the Mediterranean basin, would significantly benefit from increased drought resistance.

We investigated a diverse set of 30 durum wheat varieties, including both local landraces and modern cultivars that have proven successful in Algeria. These varieties were evaluated in field trials over two consecutive years with contrasting rainfall patterns (one very dry, the other quite wet). Grain yield (PGY), yield components, and flag leaf characteristics such as area, canopy temperature, or rolling index were evaluated. Data from previous studies of root traits recorded on the same set of genotypes at seedling and adult growth stages were used to search for possible associations with grain yield and other agronomic traits measured in the current work.

Genotypic variation was found for all traits measured under both conditions. Grain yield and aerial biomass were reduced by 76% (from 5.28 to 1.97 Mg ha^-1) and 66% (from 15.94 to 3.80 Mg ha^-1), respectively in the dry year, whereas the harvest index increased by 32%. The breeding history of the germplasm (cultivar vs. landrace) had a significant effect on the traits studied. Landraces showed higher biomass only under drought (4.27 vs. 3.63 Mg ha^-1), whereas modern cultivars out-yielded landraces only under non-drought conditions (5.56 vs. 4.49 Mg ha^-1). Promising associations were found between root and agronomic traits, especially with grain yield, indicating that a profuse (large root length) and shallow (wide root angle) root system was related to increased yield of modern cultivars only in the dry year, without penalizing yield in the wet year.

Breeding programs could improve grain yield under Algerian, semi-arid conditions, by making crosses between selected landraces with good growth potential under drought and modern cultivars, with high efficiency of biomass conversion into grain, and searching for lines with acceptable agronomic performance, which combine these desirable traits from landraces and modern cultivars, with the presence of shallow and profuse root systems.