Modulation of some key biochemical parameters in drought-stressed pea (Pisum sativum L.) treated with different plant growth regulators

Four different plant growth regulators (PGRs), viz. 25 mM trehalose (Tre), 0.02 mM nitric oxide (NO), 0.85 mM ascorbic acid (AsA), and 1.144 mM 5-aminolevulinic acid (5-ALA), were applied as a foliar spray to pea plants grown under control and drought stress (60% field capacity) conditions. Although Tre application was not effective for regulating growth parameters, application of NO and AsA increased root fresh weight and shoot and root dry weights. Of all PGRs, foliar-applied NO was found to be superior to all the regulators tested in enhancing root fresh and dry weights, AsA concentration and activity of peroxidases under stress conditions. Overall, foliar application of PGRs enhanced the activities of enzymatic and non-enzymatic antioxidants under stress conditions. Thus, the exogenous application of PGRs could be used as an effective means to minimize the adverse effects of water stress in plants.