Effect of Arthrospira platensis on alleviation of drought stress in Helianthus annuus L.

Abstract

Drought stress is a major constraint limiting sunflower (Helianthus annuus L.) productivity, reducing germination, growth, and biomass accumulation. This study evaluated the potential of Arthrospira platensis as a biostimulant to enhance drought tolerance in sunflower seedlings. Seed treatments and foliar applications of A. platensis were applied under controlled conditions, with drought stress induced by 15% polyethylene glycol (PEG-6000). Drought significantly reduced plant height, root length, and fresh biomass, while dry biomass remained largely unaffected. Treatments with A. platensis mitigated these effects, with combined seed and foliar applications increasing plant height to 123% of non-stressed controls and 138% of PEG-stressed controls, root length exceeding 150%, and fresh biomass rising from ~57% in stressed controls to over 300%. Seed priming primarily enhanced root growth, whereas spraying alone improved plant height and fresh biomass. These results indicate that A. platensis effectively enhances sunflower seedling growth under water deficit, highlighting its potential as a sustainable biostimulant for improving drought resilience.