Mitigating effects of paclobutrazol on flooding stress damage by shifting biochemical and antioxidant defense mechanisms in mungbean (Vigna radiata L.) at pre-flowering stage

Abstract

Flooding stress is one of the major obstacles which hamper plant growth and development in various ways. Two screened mungbean genotypes, HUM-16 (flooding tolerant) and HUM-12 (flooding susceptible), were selected to evaluate the effect of paclobutrazol @10ppm and 25ppm along with its combinations through pre-seed soaking and foliar spray at pre-flowering stage. The flooding stress shock was imposed for seven days at pre-flowering stage. Paclobutrazol (PBZ) treatments significantly enhanced chlorophyll, soluble sugar, starch, MSI, APX, and SOD in both HUM-16 and HUM-12 genotypes under flooding stress. Among all the treatments, PBZ @10ppm seed treatment + 10ppm foliar spray revealed higher chlorophyll (2.47 and 1.97 mg g-1 FW), soluble sugar (24.57 and 20.53 mg g-1 FW), MSI (49.16% and 38.67%), APX (16.13 and 6.50 Units mg-1 protein min-1) and SOD (38.00 and 18.30 Units mg-1 protein min-1) in both tolerant and susceptible genotype, respectively, while it minimized the production of MDA (18.30% and 49.00%) and H2O2 (19.05% and 25.06%) in both tolerant and susceptible genotype, respectively, under flooding stress as compared to control. Paclobutrazol treatments, as evident, minimized the flooding stress damage in tolerant genotype as compared to susceptible genotype by enhancing chlorophyll, soluble sugar and antioxidant enzymes activity (APX and SOD) and by reducing the generation of H2O2 and MDA contents under flooding stress.