Drought Tolerance of Mungbean Is Improved by Foliar Spray of Nanoceria

Abstract

In crops, drought stress reduces the photosynthetic rate and gamete function through oxidative damage. Earlier studies showed that nanoceria possesses an antioxidant property; however, the ability of nanoceria to alleviate drought-stress-stimulated oxidative damage in pulse crops has not been studied. Therefore, experiments were conducted to assess the impacts of nanoceria on drought-induced oxidative damage in mungbean [Vigna radiata (L.) Wilczek]. We hypothesize that foliar application of nanoceria under drought stress can scavenge the excess produced reactive oxygen species (ROS) due to its inherent properties which could result in increased photosynthesis and reproductive success of mungbean. Three experiments were conducted under well-watered and limited-moisture conditions. The traits associated with oxidative damage, photosynthesis, reproductive success, and yield were recorded. Results showed that for mungbean, the optimum concentration of nanoceria for foliar spray was 100 mg L−1. Field and pot culture experiments showed that foliar application of nanoceria under drought decreased the superoxide radical content (29%), hydrogen peroxide content (28%), and membrane damage (35%) over water spray. Nanoceria increased the photosynthetic rate (38%), pod-set percentage (16%), and seed weight m−2 (44%) in drought-stressed plants compared to control plants. The increased photosynthetic rate by nanoceria spray under drought stress is associated with lesser oxidative damage and stomatal limitation caused by nanoceria’s inherent ROS-scavenging ability. Hence, foliar application of nanoceria at the rate of 100 mg L−1 under drought stress could increase mungbean seed yield per plant through increased photosynthetic rate and pod-set percentage.