Synergistic effect of biochar and plant growth promoting bacteria improve the growth and phytostabilization potential of Sorghum bicolor in Cd and Zn contaminated soils

Combined Application of Biochar and Plant Growth-Promoting Rhizobacteria Improves Heavy Metal and Drought Stress Tolerance in Zea mays

“…However, the accumulation of proline under HM, drought, and HM+drought stress conditions was significantly lower in ARN7- and GS-BC-treated plants compared to their respective control counterparts ( Figure 3 b). Similar observations were previously documented by Anbuganesan et al [ 7 ] and Tripti et al [ 16 ] where they noted reduced proline content upon the application of biochar and PGP bacteria under HM and drought stress conditions and suggested that treatment with biochar and PGP bacteria cumulatively reduced the stress effects caused by HM and drought.…”

“…The result revealed that the strain ARN7 could efficiently colonize the rhizosphere soil of Z. mays irrespective of HM and/or drought stress conditions ( Figure 5 e). However, as compared with the nonstressed condition, though a slight decrease in colonization was found in HM, drought, and combined stress conditions, GS-BC application under the aforementioned stress conditions improved the colonization efficacy of ARN7 indicating that GS-BC could protect the ARN7 from HM and drought stress by changing soil properties, providing nutrients, retaining soil moisture, and reducing HM toxicity and availability [ 7 , 12 , 15 ]. Therefore, the increased plant growth and physiological attributes caused by ARN7 + GS-BC treatment under HM, drought, or HM+drought stress highlights that GS-BS could improve soil quality including enzymatic activity and ARN7 colonization, growth, and PGP activity, thereby mitigating the negative effects of HM and drought stress in plants.…”

“…An in vitro phytagar assay was carried out to assess the plant growth-promoting potential of ARN7 on Z. mays as per the protocol described by Ma et al [ 54 ]. For in vitro studies, healthy seeds procured from the local market were surface sterilized, inoculated with ARN7, and allowed to grow for 20 d as described previously [ 7 , 20 ].…”

“…Under HM stress, the application of biochar derived from various agriculture biomass, including banana pith, cotton straw, rice straw, etc., improves plant growth, nutrient uptake, physiology, and HM stress tolerance by improving antioxidant enzyme activities such as superoxide dismutase (SOD), ascorbate peroxidase (APX), catalase (CAT), etc. [ 7 , 8 , 9 ]. An increment in the activity of extracellular enzymes including β-glucosidase, which is involved in soil nutrient cycling, has also been reported with the addition of biochar in HM-contaminated soils [ 10 , 11 ].…”

“…PGPR with the potential to tolerate abiotic stresses including HM, drought, etc., can colonize the plant rhizosphere and exhibit beneficial effects on plants by synthesizing various plant growth-promoting (PGP) substances such as 1-aminocyclopropane-1-carboxylate deaminase, siderophores, indole-3-acetic acid (IAA), exopolysaccharides, antimicrobial metabolites, N fixation, and solubilizing P, K, Zn, etc. [ 7 , 18 ]. Moreover, such microbes can effectively increase HM and drought stress tolerance in plants by triggering the metabolic pathways of the plant, stimulating antioxidant production, modulating the expression of specific stress-responsive genes, etc.…”