Document Type : Original Article
Authors
1
Department of Horticultural Sciences and Engineering, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
2
Department of Horticultural Sciences and Engineering, Faculty of Agriculture,,University of Zanjan, Zanjan, Iran
3
Department of Horticultural Science and Engineering, Faculty of Agriculture, University of Kurdistan, Sanandaj, Iran
4
Department of Horticultural Sciences and Engineeing, Faculty of Agriculture, University of Zanjan, Zanjan, Iran
10.22034/plant.2026.145777.1198
Abstract
Introduction: Salinity stress significantly reduces plant growth, photosynthesis, and yield through osmotic pressure, toxicity of sodium and chloride ions, disruption in the uptake of essential nutrients, and increased generation of reactive oxygen species. Spinach (Spinacia oleracea L.) is a leafy vegetable that is sensitive to salinity, and its yield decreases under saline conditions. The development of salt-tolerant cultivars through genetic variability is a key strategy to address this challenge. Chemical mutagenesis using mutagens such as ethyl methanesulfonate (EMS) is a valuable tool in breeding programs due to its ability to induce point mutations and broad phenotypic variation. This study was conducted to evaluate the effects of different EMS concentrations and salinity levels on morphophysiological traits of spinach cv. Viroflay and to determine the optimum EMS concentration for alleviating adverse effects of salinity.
Materials and Methods: This study was conducted in the greenhouse of the University of Kurdistan during 2022 and 2023 as a factorial arrangement based on a completely randomized design with three replications. The first factor was four EMS levels (control, 0.25, 0.5, and 1%) and the second was four salinity levels of irrigation water with sodium chloride (control, 0.75, 4, and 8 dS m⁻¹). After surface sterilization and pericarp removal, seeds were treated with EMS in 100 mM phosphate buffer for 75 minutes in darkness, then sown in 3.5-L pots containing a mixture of cocopeat, perlite, sand, and compost. Salinity treatments applied through irrigation three times per week. Measured traits included leaf length and width, petiole length and diameter, leaf number, shoot fresh and dry weight, chlorophyll a and b (Lichtenthaler method), proline (Bates), protein (Bradford), and concentrations of sodium, potassium, phosphorus, and iron. Data were analyzed using SAS software (version 9.4), and means were compared using Duncan's test at the 5% probability level.
Results: Increasing salinity, especially at 8 dS m⁻¹, significantly reduced leaf length and width, leaf number, petiole length and diameter, shoot fresh and dry weight, chlorophyll a and b, potassium, phosphorus, and protein contents, while increasing sodium and proline accumulation. The lowest shoot fresh weight (9.76 g) and dry weight (0.788 g) were recorded at 8 dS m⁻¹ salinity. Among EMS treatments, 0.25% showed the best performance, with the highest leaf length (10.73 cm), leaf number (18.40), shoot fresh weight (16.93 g), chlorophyll a (2.536 mg g⁻¹), and iron (29.45 mg kg⁻¹) obtained in this treatment. The interaction effect showed the highest proline under 8 dS m⁻¹ combined with 0.25% EMS and the lowest in the control, while the highest shoot fresh and dry weights (16.93 and 2.14 g) were observed under non-saline conditions combined with 0.25% EMS.
Discussion and Conclusion: The reduction in growth and physiological parameters under salinity can be attributed to disruption of osmotic balance, degradation of the photosynthetic protein-pigment complex, inhibition of magnesium uptake, and increased reactive oxygen species. Proline accumulation plays a vital role in maintaining cell turgor, osmotic adjustment, and scavenging of free radicals. EMS at 0.25%, through inducing beneficial point mutations, alleviated the negative effects of salinity and improved growth attributes, photosynthetic pigments, and mineral nutrient balance. At higher EMS concentrations (1%), enzyme disruption, hormonal imbalance, and inhibition of cell division resulted in growth reduction. Controlled application of 0.25% EMS can be an effective tool for inducing genetic variability and enhancing salinity tolerance in spinach breeding programs.
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