Co-application of humic acid, potassium dihydrogen phosphate and melatonin (osmo-regulators) ameliorate the effects of drought stress in Barley (Hordeum vulgare L.)

Abstract

Purpose Drought has an adverse impact on the production and growth of cereals globally. Due to drought stress, cereals’ cultivation declined day by day, worldwide. Hence, ultimate yield does not fulfill the required demand. The current research investigated the consequences of drought stress on morpho-physiological, yield and biochemical parameters of barley plants and a comparison of different osmo-regulators and their ameliorating capacity towards drought stress. Methods A pot trial was held in a completely randomized (CR) design with three replicates manner to investigate the role of humic acid, potassium dihydrogen phosphate and melatonin (osmo-regulators) synergistic application in ameliorating drought stress. Three barely varieties (Haider-93, Sultan-17 and Jau-17) were selected for this experiment. The treatments applied were as follows; humic acid (400 ppm), potassium dihydrogen phosphate (20 ppm) and melatonin (0.5 mM) with two water levels i.e., Control (normal watering) and drought stress (stop watering). Results Results indicated that foliar application of all osmo-regulators improved propagation, antioxidants, proteins, chlorophyll, mineral contents and productivity parameters, while alleviate Malondialdehyde content, hydrogen peroxide and relative membrane permeability value studied under drought stress and non-drought stress. The maximum yield was noticed in Jau-17 plants given humic acid in control and drought stress in Jau-17. The order of effectiveness of osmo-regulators in this study was humic acid > melatonin > potassium dihydrogen phosphate. Conclusion Osmo-regulators examined in this study had potential role in combating against drought stress and could also be effective for various other abiotic stresses.