Effects of salicylic acid applications on the physiology and development of cardinal and victoria grapevines under deficit irrigation conditions in soilless culture

Under the increasing pressure of environmental stress factors, ensuring sustainable nutrition for the world's population critically depends on managing the various stressors that adversely affect plant growth and on developing strategies to minimize the impact of these unfavorable conditions on plants. In this context, salicylic acid (SA) is an important molecule that plays a role in mitigating a range of abiotic and biotic stresses in plants. Applications of SA in different plant species have yielded positive outcomes in protecting plants against various stress factors. However, in grape production, studies on the use of SA remain rather limited. In this study, conducted in the glasshouse belonging to Selçuk University, Faculty of Agriculture, Department of Horticulture, Division of Grape Growing and Breeding, the physiological and vegetative responses of 'Cardinal' and 'Victoria' table grapes grafted on Rupestris du Lot rootstock to leaf SA treatments under the full irrigation (FI; field capacity) and deficit irrigation (DI; 50% of field capacity) conditions were investigated. In the study, the vines grown in soilless culture containing pomza and perlite in equal amounts were used. Foliar SA at 0.5 mM concentration was applied to vines three times with one month interval when the interior temperature reached 40 °C and the shoots were around 40 cm long in the early summer period. DI conditions led to decreases in leaf relative water content and stomatal conductance; while it increased the malondialdehyde and electrolyte leakage, the physiological stress substances. Furthermore, DI had significant adverse effects on the vegetative developments of the vines. On the other hand, foliar SA treatments, under DI condition with the particular interest, provided remarkable increase in physiological activities and vegetative developments of the vines. Therefore, foliar SA applications could be recommended for a sustainable viticulture under the increasing effects of drought conditions exacerbated by the climate change.