Screening for Suitable Melatonin Application Scheme to Modulate Drought Stress in Bulgarian Wheat

Abstract

Drought occupies a dominant share among the environmental factors that directly cause significant economic losses. Wheat is one of the most important crops for humankind, and although it tolerates drought to a certain extent, prolonged water deficit provokes a number of unfavourable alterations in plants, which lead to a significant decrease in productivity. Because of the broadening climate changes, the search for ecological biostimulants as an innovative approach to reduce the harmful effects of drought is gaining more popularity in modern agriculture. Melatonin is a natural product of plant metabolism with growth-regulating properties – it is non-toxic and is safe for the environment. We aimed to investigate the possibilities to modulate the negative effects of drought through application of melatonin using a comparative analysis of the physiological reactions of young wheat seedlings. We studied the effects of melatonin applied before drought on the physiological responses of two Bulgarian wheat cultivars grown as a soil culture. Different concentrations of melatonin ranging from 5 to 500 μM were tested and 75 μM was selected as a promising one. Additionally, we tested the method of application of melatonin – leaf spray or root supplement. Based on the content of selected stress markers we could make a conclusion that leaf spraying of plants before stress had some attenuating effect on the negative consequences of drought, but one dose of root application appeared to be more effective.

Abbreviations: MDA – malondialdehyde, Mel – melatonin, ROS – reactive oxygen species