Physiological and Biochemical Underpinnings Drive Yield Enhancement in Indian Mustard (Brassica juncea) by Ortho Silicic Acid under Field Conditions

Mustard (Brassica juncea) is a major oilseed and medicinal crop and its consumption has considerably increased with growing human population, leading to greater demand than supply. Increasing production and productivity of oilseed brassica to meet out the projected demand of edible oils, crop management strategies need to be fabricated and implemented. The two varieties of mustard, RH 725 and RH 0749 display superior performance for yield and are recommended for farmers’ fields in north India. The present study evaluated the efficacy of silicon applied in the form of orthosilicic acid (OSA) for improving the physiological and biochemical performances, growth, and yield of recommended mustard varieties under field conditions, as a function of variety, stage, dose, and application time. OSA was applied as a foliar spray at 20, 30, and 40 ppm during vegetative and flowering stages to analyse its influence on plant growth, physiology, enzymatic and non-enzymatic antioxidant enzymes, and yield attributes. Application of OSA at 30 ppm at vegetative stage and 20 ppm at flowering stage, increased activity of antioxidant enzymes, superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and peroxidase (POX) and metabolites, ascorbic acid and glutathione; and decreased the levels of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), and relative stress injury (RSI), as compared to the respective untreated controls. The increase in antioxidant enzyme activity and ascorbic acid and glutathione content and protein content was greater in RH 0749 than RH 725. Photosynthetic rate, stomatal conductance, transpiration rate, and chlorophyll fluorescence and protein content improved with the application of 20 ppm OSA, where RH 0749 responded more at the vegetative stage whereas RH 725 showed better responses at flowering stage. The growth and yield related attributes also enhanced with the foliar application of 20 ppm and 30 ppm OSA in both the varieties. RH 725 displayed an increase of 15% and RH 0749 displayed an increase of 18% in seed yield with 20 ppm OSA. Single foliar application of OSA could yield pronounced effects on growth, physiological and biochemical responses and yield of Brassica varieties. The present study indicates the ability of OSA in low dosesto modulate crop physiological and biochemical responses under field conditions can contribute to bridging the productivity gap of brassica to meet consumer demand for establishing a sustainable cropping system.

Graphical Abstract

Diagrammatic overview of Brassica juncea varieties subjected to OSA treatments during the vegetative and flowering stages for the experiment. 20 ppm OSA was found to be optimum dosage for improving crop productivity, according to the analysis of specific growth, physio-biochemical and yield parameters.