Effects of Magnetic Field and Ultrasound Applications on Endogenous Melatonin Content and Drought Stress Tolerance of Pepper Seedlings

Abstract

Uncertainty about climate change exposes agriculture to high risks. Magnetic field (MF) applications are one of the methods that can be used to reduce the effects of environmental stress conditions. Melatonin (MEL) acts as a broad-spectrum antioxidant in eliminating the effects of damage caused in plants exposed to stress. This study aims to examine the effect of MF and ultrasound (US) applications on endogenous MEL levels in peppers and investigate the usability of treated seeds against drought stress. Pre-sowing pepper seeds, 0, 0.3, 0.9, 1.1 T MF and 0, 15, 30 min 40 Hz US were applied. The results show that the highest increase in MEL content was detected at 0.3 T MF with 82% and with 30 min of US application at 98%. MF and US treatments decreased the malondialdehyde (MDA) (19% and 35%, respectively) and hydrogen peroxide (H2O2) (52% and 58%, respectively) contents in seedlings. An increase of 24% and 22% (MF-US, respectively) was observed in catalase (CAT) enzyme activity with these applications. As a result, it was observed that MF and US treatments increased the endogenous MEL content and provided tolerance against drought stress. MF and US applications could be suggested as methods to increase drought tolerance in peppers by increasing the endogenous MEL content.

Melatonin Interaction with Other Phytohormones in the Regulation of Abiotic Stresses in Horticultural Plants

“…Stress Mitigation in Horticultural Crops: Impacts of MT Several studies have suggested that MT is a well-known plant hormone in response to stress conditions (Figure 2) [28]. MT regulated seed germination in cucumber under salinity stress [62], upregulating nitrogen metabolism in pepper under drought stress [63], modulated the antioxidant defense mechanism in Camellia sinensis L. under cold stress [64], reduced oxidative damage and enhanced the defense mechanism in strawberry under heat stress [65], increased photosynthetic efficiency in sweet potato under chromium toxicity [66], and increased mineral nutrient accumulation in tomato under nickel toxicity [67]. Consequently, the investigation of exogenous MT in stressed plants, with regard to plant adaptability and survival, has been receiving significant attention from researchers.…”