Drought is a major abiotic stress, affecting the metabolism, growth, and productivity of plants worldwide. Therefore, this study aimed/hypothesized to investigate the ameliorative effects of biochar and rhizobacteria in drought-damaged Brassica napus L. genotypes. The plants were divided into two groups based on the drought stress employment (15 days and 30 days). Both groups were then treated with PGPR, biochar, and their co-application, and the samples were taken from shoots and roots of both genotypes. Our results revealed that the drought resulted in a substantial decline in total flavonoids, phenolics, proteins, peroxidase (POD), superoxide dismutase (SOD), glutathione reductase (GR) as well as nutrient uptake in shoots and roots of both the studied genotypes. Contrarily, sugar and glycine betaine (GB) contents increased in both shoots and roots under drought stress conditions. However, the plants with co-application of biochar and PGPR showed better improvement of nutrient uptake, leaf relative water content (RWC), and growth parameters compared to drought-stressed, control, and the plants with sole biochar and PGPR application. In addition, the co-application of PGPR and biochar produced higher levels of sugar, proteins, flavonoids, phenolic compounds, and enzymatic activities (POD, SOD, GR, and dehydroascorbate reductase (DHAR)) than those that were not treated with biochar and PGPR or treated solely. Relative to Westar genotype, the Punjab sarson showed higher drought tolerance. In conclusion, we suggest that the co-application of biochar and PGPR can be an effective strategy for overcoming the drought-induced damage in plants.
