Foliar application and seed priming of salicylic acid affect growth, fruit yield, and quality of grape tomato under drought stress

Drought, an acute abiotic stress, limits growth and yields of crops including tomato. Salicylic acid (SA) has been widely used as an abiotic stress mitigating agent in various crops. Two experiments were conducted to assess the effects of SA applied as a foliar spray and as a seed priming material on growth, yield, and fruit quality of grape tomato under drought stress. In the first experiment, SA was applied as a foliar spray in five doses (0, 50, 100, 150, and 200 mg L-1) under three soil moisture regimes (50 %, 75 %, and 100 % field capacity [FC]). In the second experiment, doses of SA and soil moisture regimes were the same as first experiment, except that SA was applied as a seed priming material. Data on growth, fruit yield, and quality of grape tomato were collected. The results revealed that severe moisture deficit of 50 % FC adversely affected growth and fruit yield of grape tomato by 94 % in experiment 1 (foliar application of SA) and by 95 % in experiment 2 (seed priming of SA) compared with 100 % FC, while fruit quality parameters (fruit pH, total soluble solids, and color index) improved with reducing soil moisture regime. Exogenous application of SA at 150 mg L-1 as a foliar spray enhanced fruit yield by 41 % and at 100 mg L-1 as a seed priming material resulted in 33 % increase in fruit yield compared with the control. However, there was no effect of SA supplementation at severe moisture deficit of 50 % FC regardless of experiments and doses. Foliar application of SA at 150 mg L-1 resulted in statistically similar yields between moderate soil moisture level of 75 % FC and sufficient soil moisture level of 100 % FC, whereas in case of seed priming treatment, maximum fruit yield was obtained at 100 mg L-1 SA dose in combination with 100 % FC. Grape tomato yielded more with foliar application of SA (113.1 g plant(-1) fruit yield at 150 mg L-1) than did with SA seed priming (87.8 g plant(-1) fruit yield at 100 mg L-1). Exogenous application of SA at 150 mg L-1 as a foliar spray and at 100 mg L-1 as a seed priming material could be recommended when grape tomato is grown under moderate to sufficient soil moisture availability.