Nitrogen fertilizer alleviates root-knot nematode stress in beetroot by suppressing the pathogen while modulating the antioxidant defense system and cell viability of the host

Abstract

The ongoing removal of environmentally harmful nematicides from the global market necessitates the development of new nematode management strategies. Therefore, alternate approaches that are eco-friendly are preferable to manage the menace of root-knot disease in agroecosystems. The current study sought to evaluate and determine the optimum level of nitrogen fertilizer with respect to its plant growth promoting and nematicidal activities. Among the different concentrations of nitrogen fertilizer supplemented to the soil, U150Mi (150 kg/h N) was found most optimum to considerably (P ≤ 0.05) improve the growth and yield attributes of beetroot inoculated with Meloidogyne incognita. Scanning electron microscopy demonstrated the improvement in stomatal attributes of beetroot at U150Mi (150 kg/h N) as compared to the untreated inoculated control. Confocal laser microscopy confirmed the dose-dependent nematicidal properties of nitrogen fertilizer under laboratory conditions. The cell viability of beetroot was also markedly improved at U150Mi (150 kg/h N) nitrogen fertilizer level. The formation of galls and egg masses was suppressed significantly with the application of nitrogen fertilizer at U150Mi (150 kg/h N) level. The PCA (principal component analysis) accounted for 99.61% for the total-data variability in plants inoculated with M. incognita and treated with different nitrogen fertilizer levels.