Development of wheat (Triticum aestivum L.) populations with improved biomass through chemical mutagenesis for moisture stress tolerance

Background Wheat ( Triticum aestivum L. ) is member of Poaceae family and its productivity progressively declining due to increased drought stress, a phenomenon intensified by the ongoing effects of climate change. Mutation breeding emerges as a promising strategy for improving stress tolerance in crops. It enables the development of beneficial traits without altering the entire genetic makeup of the plant. This study aimed to develop a chemically mutagenized population of two high-yielding winter wheat cultivars, HD-3226 and HI-1620, to identify drought-tolerant lines through induced phenotypic variation. Methods Ethyl methane sulphonate (EMS) and sodium azide (SA) are commonly used chemical mutagens known for their efficiency in inducing random point mutations. Mature seeds were treated with varying concentrations of EMS (0.25, 0.5, 0.75 and 1%) and sodium azide (SA; 0.02, 0.04 and 0.08%) during the 2020–2021 rabi season under water stress conditions at SVPUA&T, Meerut, India. M ₁ plants were initially screened using a 15% PEG solution, and promising lines were further evaluated in the M ₂ generation under drought (three irrigations) and control (five irrigations) conditions in the field. Results The M ₂ population exhibited diverse morphological mutations, particularly in plant height, tiller number, and spike traits. While EMS generally reduced plant height, SA, especially at 0.04%, increased it, most notably in HD-3226. Under stress, SA treatments sustained better tiller production and biological yield, with EMS 0.25% showing optimal performance in HI-1620, indicating genotype-specific mutagen sensitivity. Flag leaf length and area, crucial for photosynthetic efficiency, were better maintained under SA treatments, particularly at 0.02% and 0.04%. Although drought reduced spike traits and grain yield, some M ₂ lines recovered these characteristics, with SA 0.02% showing the most stable effects. Additionally, phenological delays were more pronounced in HI-1620, whereas HD-3226 showed later maturity under stress. Conclusions Higher doses of EMS negatively impacted yield components, while lower SA concentrations mitigated drought-related losses. Overall, SA at lower concentrations proved more effective than EMS in enhancing drought resilience and agronomic performance. The generated mutant lines offer valuable genetic variability for breeding drought-tolerant wheat suited for water-limited environments. This approach not only facilitates functional genomic studies but also enhances genetic diversity, offering a valuable supplement to traditional breeding techniques.