Efficacy of Biostimulants in Mitigating Drought Stress in Wheat ( <scp> <i>Triticum durum</i> </scp> L.) Over Two Growing Seasons

Abstract

ABSTRACT This study aimed to compare the impact of biostimulants on wheat ( Triticum durum L.) in two consecutive field experiments conducted in 2023 and 2024. The experiments tested the effects of Bacillus sp., Bacillus subtilis (R), arbuscular mycorrhizal fungi (M), and compost (C) under two irrigation regimes: 100% crop evapotranspiration (ETc) for well‐watered conditions and 30% ETc for drought stress. Furthermore, the research focused on the combined and individual impacts of these biostimulants on wheat growth, yield and soil properties. The obtained results showed that drought stress caused significant declines in biomass, physiological traits and biochemical markers in both years. Furthermore, the application of biostimulants, especially C + M and M + R combinations, resulted in significant improvements. In 2023, shoot and root dry weights under drought stress increased by 137% and 72%, respectively, compared with the control. The 2024 results confirmed similar trends, with grain and straw yields rising by 167% and 130%, respectively. Additionally, biostimulants/biofertilisers positively impacted soil quality highlighting their role in enhancing wheat's resilience to drought through improved soil–plant interactions. These results underline the long‐term benefits of integrating biostimulants/biofertilisers into wheat farming under water‐limited conditions.