Hormonal regulation and redox reaction of maize under partial root drying irrigation

Abstract

How three different irrigation regimes, conventional irrigation (CI), partial root drying (PRD), and deficit irrigation (DI), on endogenous hormonal abscisic acid (ABA) and zeatin-riboside (ZR) changes, stomatal conductance (gs), reactive oxygen species (ROS), antioxidant enzyme activities, and metabolism of non-enzymatic compounds was assessed. This investigation revealed that the root-sourced chemical signals induced by PRD irrigation reduced the gs without any altered relative water content (RWC) in leaves, and further analysis found that stress-triggered ABA could induce stomatal closure; however, ZR exhibited antagonistic effects on the accumulation and stomatal regulation of ABA. Thus, in the current study, gs was more responsive to the combined ABA/ZR signal than ABA signal solely. Both PRD and DI treatments increased the production rate of superoxide anion ( $$ {\text{O}}_{2}^{ \bullet - } $$ ) as well as hydrogen peroxide (H2O2) concentration in root and leaf tissues under stress conditions; however, the superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) activities significantly increased under PRD irrigation. Moreover, compared with DI regime, PRD irrigation caused less proline and malondialdehyde (MDA) accumulation in stressed root and leaf tissues, suggesting that PRD irrigation technique alleviated the stress-induced physiological damage. Consequently, compared to CI, the leaf area and whole-plant dry weight in maize were unchanged under PRD irrigation but reduced significantly under DI treatment.