Management of yield losses in Vigna radiata (L.) R. Wilczek crop caused by charcoal-rot disease through synergistic application of biochar and zinc oxide nanoparticles as boosting fertilizers and nanofungicides

Abstract

The mung bean crop (Vigna radiata (L.) R. Wilczek) is widely recognized as a key source of pulse food worldwide. However, this crop suffers substantial yield losses due to humid environments, particularly from infestations by the fungal pathogen Macrophomina phaseolina, which causes charcoal rot disease. This infestation results in significant agronomic losses, affecting both the crop's growth characteristics and overall yield. Previous research suggests that these losses can be mitigated through environmentally friendly soil amendments, such as biochar, as well as by applying various nanofungicides. This study aims to explore the potential of biochar and zinc oxide nanoparticles (ZnONPs) to reduce the severity of charcoal rot disease and enhance the agronomic traits and yield of mung bean plants affected by this disease. The experiment was conducted in triplicate, applying ZnONPs at three concentrations (5, 10, and 20 mg. L^{- 1}) via foliar spraying, combined with two levels of biochar (20 g and 40 g per pot). Positive and negative control treatments were also included for comparison. The results demonstrated that applying 40 g of biochar per pot and 20 mg. L^{- 1} of foliar-applied ZnONPs increased the activities of the anti-oxidative defence enzymes. Additionally, this treatment strategy boosted the plants' disease resistance mechanisms, leading to lower mortality rates and reduced levels of malondialdehyde (MDA) and hydrogen peroxide (H₂O₂) by 61.7% and 49.23%. Moreover, the treatment positively impacted key growth parameters, increasing total chlorophyll content by 43%, plant height by 47%, and legume count per plant by 80.4%. The application of biochar and ZnONPs also improved seed protein content, reflecting an enhancement in nutritional quality. This study supports the use of biochar and ZnONPs as biostimulants to manage yield losses in mung bean crops affected by charcoal rot disease. The future prospects of using ZnONPs and biochar as treatments in agriculture are promising, as they offer innovative, eco-friendly solutions to enhance crop productivity, improve soil health, and reduce reliance on synthetic chemicals, paving the way for more sustainable and resilient agricultural systems.

Keywords: Antioxidant enzymes; Biochar; Charcoal-rot disease; Eco-friendly; Mung bean; Nanofungicides; Zinc oxide nanoparticles.