Seed priming with polyethylene glycol improved drought tolerance of late sown wheat by enhanced gas exchange attributes

Late sowing, especially in regions prone to drought, significantly hampers crop growth and yield. To address this, field experiments were conducted during the winter of 2021–2022 at Maru and Mushaqar in Jordan to evaluate the effects of seed priming agents as seed priming with water (hydropriming), polyethylene glycol (osmopriming), calcium chloride (osmopriming), and a control (unprimed) on physiological, phenological and yield traits of durum wheat (umqais variety) under normal and late sowing conditions. Results showed that Maru exhibited superior performance in physiology, growth, and yield attributes compared to Mushaqar. While late sown wheat demonstrated better water use efficiency, normal sowing conditions generally favored other yield components. Seed priming by polyethylene glycol (PEG) improved relative water content, stomatal conductance, and grain yield compared to other treatments. Mushaqar recorded higher grain spike-1 and spike m-2 under normal sowing, while PEG-primed seeds produced significantly higher 1,000-grain weight and harvest index. Notably, PEG-primed seeds improved grain yield and 1,000-grain weight, suggesting enhanced drought resilience under late sowing conditions. The study concludes that seed priming, especially with PEG, effectively improves drought tolerance in late sown wheat by enhancing photosynthetic activity, chlorophyll content (SPAD), and water retention. The findings indicate that PEG seed priming can effectively mitigate the negative impacts of late sowing, supporting its use as a practical strategy for improving wheat performance in semi-arid environments.