The Effects of Exogenous Salicylic Acid and Strigolactone Applications on Seedling Growth and Antioxidant Activity in Tomato Seedlings Under Short-Term Drought Stress

Drought is the main abiotic stress factor that negatively affects the growth, development, and yield of plants. Salicylic acid (SA) is a plant growth regulator associated with stress tolerance in plants. Exogenous application of SA prevents against stress dependent damage. Strigolactones (SLs) are another phytohormone in plants, they are known to positively affect plant growth with exogenous applications due to their potential to stimulate the tolerance system of plants under stress conditions. The aim of this study is determine to SA and GR24 effects on the negative impacts of drought stress on tomato “Full F1” seedlings, which is the most preferred commercial variety by professional farmers in Çanakkale (Turkey), based on physiological [(shoot-root length, biomass, relative water content (RWC), specific leaf area (SLA), total chlorophyll content (SPAD)] and biochemical parameters [Total protein amount, glutathione reductase activity (GR), catalase activity (CAT), peroxidase activity (POX), ascorbate peroxidase activity (APX), hydrogen peroxide amount (H2O2), lipid peroxidation amount (TBARS)]. Fourty-five days old seedlings kept five days for acclimation, then the seedlings were treated with exogenous GR24 (0.015 mM) and SA (0.1 mM) applications. According to our results, Full F1 tomato variety was adversely affected by short-term drought stress. However, especially SA+GR24 application reduced lipid peroxidation by regulating antioxidant capacity and increased drought tolerance of this cultivar. In this context, it can be said that the combined use of these phytohormones can be used to protect the Full F1 tomato variety from drought stress damage.