The Effect of Low-Level Laser Radiation on Some Traits of Wheat (Triticum aestivum L.) Under Drought Stress

Wheat ( Triticum aestivum L.), a major global staple crop, is highly vulnerable to drought stress, which substantially constrains growth and yield. Emerging evidence suggests that low-level laser irradiation may serve as an effective priming strategy to enhance plant tolerance to environmental stresses. In the present study, wheat seeds were pre-treated with low-level laser radiation (740 nm) for different exposure durations (0, 45, 65, and 85 s) and subsequently grown under controlled pot conditions subjected to two irrigation regimes (80% and 40% field capacity). Laser pre-treatment for 45 and 65 s significantly improved morphological and physiological traits, including plant height, tiller number, node number, carotenoid content, and proline accumulation. Notably, laser-treated plants exhibited enhanced tolerance to drought stress, with pronounced improvements in both growth-related and biochemical parameters compared with untreated controls. Optimal laser exposure (~ 60 s) on wheat dry seeds appeared to promote dry weight of arial part of plant in no-stress condition and alleviate detrimental drought stress effect, sink-related traits, such as tiller and node formation, potentially through modulation of proline metabolism biosynthesis, which function as key osmoprotective and antioxidant mechanisms. This priming-like phenomenon is probable attributed to epigenetic changes in expression of mechanisms involved in free radicals scavenging, specially under drought stress, to alleviate the stress effects as a results of laser pre-treatment.