Evaluation of the possibility of alleviating the effects of salt stress in wheat by using potassium silicate and melatonin

ABSTRACT
Background and objectives: Salinity stress is considered one of the most important abiotic stresses in agriculture, which reduces crop production and threatens food security on a global scale. To cope with salinity, plants use various strategies in response to stress, such as osmotic regulation, ionic homeostasis, increased production of antioxidants, etc. Stress-reducing compounds such as potassium silicate and melatonin can be discussed by helping to facilitate physiological responses under stress conditions. This experiment was consucted to evaluate the effect of different concentrations of melatonin and potassium silicate on growth performance of wheat plants.
Materials and methods: This study was conducted in split plots based on a randomized complete block design with three replications in the research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad, in 1404 on wheat cultivar Pishgam under salt stress conditions. Salinity treatments were considered at two levels of 0.5 (as contron) and 10 dS/m, potassium silicate levels (0.5, 1.0, and 2.0 mM) and melatonin levels (100, 150, 200 μM) and control. Morphologic parameters including plants and leaf survival indices, leaf raea and dry matter acummulation were recorded. Growth indices and biochemical parameters such as chloropyll content, proline, membrane stability index, and antioxidant enzyme activity were measured.
Results: The results showed that salinity stress significantly reduced plant and leaf survival, shoot dry weight, membrane stability index and photosynthetic pigments. With the application of 2 mM potassium silicate and 200 mM melatonin, the plant survival percentage (44.65%), shoot dry weight (11.15%), membrane stability index (59.61%), photosynthetic pigments (33.35%), anti oxidant enzyme activity including catalase activity (22.16%) and ascorbate peroxidase (28.16%) increased under salinity stress, respectively. Conversely, the application of melatonin and potassium silicate significantly reduced the contents of proline and malondialdehyde, Conversely, the decreased accumulation of proline and malondialdehyde following melatonin and potassium silicate application suggests an alleviation of osmotic and oxidative stress, indicating that treated plants experienced a substantially lower stress level than the untreated controls. Correlation coefficients showed that shoot dry weight (r=0.82**), total photosynthetic pigment content (r=0.87**), membrane stability index (r=0.76**), plant height (r=0.77**), and leaf area (r=0.69**) had a positive and significant correlation with plant survival.
Conclusion: In general, the results showed that the application of stress-mitigating compounds can reduce the negative effects of salt stress and improve growth indices such as plant height, leaf area, and increase wheat resistance to oxidative stress, and can be used in saline land management programs to increase salt tolerance and production sustainability in arid regions.

Keywords: Catalase, Malondialdehyde, Proline, Shoot Dry Weight, Survival