Use of biostimulants for water stress mitigation in two durum wheat (Triticum durum Desf.) genotypes with different drought tolerance

• GBS analysis identified variants in response to water-related genes. • Drought increased oxidative stress and reduced stomata density in sensitive cv Iride. • Biostimulants allow to mitigate drought stress in sensitive DW cultivars. Agriculture is facing complex and unprecedented challenges, such as climate change and global population growth, associated with the increase of food demand. Durum wheat (DW) is a strategic crop for food security in the Mediterranean region. In this work, the effect of two biostimulant compounds on drought response of two DW genotypes with different drought tolerance degree was evaluated: the tolerant genotype Svems16 and the sensitive cv. Iride. Genotyping-By-Sequencing analysis allowed to identify variants in response to water-related genes, such as those encoding dehydrins, with Svems16 exhibiting a missense variant divergent from the sequence found in Iride. Drought significantly hindered growth of cv. Iride by increasing oxidative stress and diminishing stomata density. This difficulty was mitigated by the application of biostimulants, which induced root morphological changes, and increased stomata density. On the other hand, the growth of Svems16 seedlings was not significantly affected by drought, confirming its significant degree of tolerance toward that stress compared with Iride. As a result, both biostimulants showed limited efficacy when applied to Svems16 stressed plants. In conclusion, the application of biostimulants emerges as a valuable agronomic strategy for mitigating drought stress in sensitive DW cultivars.