Effect of seaweed extract and foliar spray of smoked water on the growth of tomato under alkalinity stress

Alkaline conditions inhibit plants growth, resulting in reduced yield and quality of field crops. Various soil and foliar amendments, such as seaweed extract (SWE) and smoked water (SW) are widely used as a biostimulant to improve plant growth and development and to enhance resistance to abiotic stress. In the current study, a pot experiment was comprising of two factors i.e., alkalinity stress (with 100 mM NaHCO 3 :Na 2 CO 3 in a ratio of 9:1), and six treatments of SWE and SW (control; seaweed extract 3%; smoked water 1:150; smoked water 1:300; seaweed extract and smoked water 1:150; seaweed extract and smoked water 1:300) was applied to the tomato plants. Results showed that the alkaline conditions had significant impact on growth, biomass, and photosynthetic characteristics of tomato plants. But combinatorial use of SWE and SW showed improvement in growth, biomass, photosynthetic properties, and decreased plant membrane damage and lipid peroxidation. These biostimulant combinations improved the carotenoids content (41.06%), soluble protein contents (98.23%), and decreased the electrolyte leakage (55.53%) as compared to control (no SWE and SW application). The optimal use of SWE and SW had significant effects on ionic homeostasis in tomato leaves. The combined effect of SW and SWE significantly reduced sodium (Na + ) ions (80.00%), chloride ions (Cl - ) (53.00%) and significantly increased in potassium ions (K + ) (311%) in leaves. Overall, the combined effect of SWE (3%) and SW (1:300) demonstrate the potential as an effective and sustainable approach for increasing alkalinity tolerance in tomato plants.