Chitosan Beads-Infused Biochar for Enhancing Physio-Chemical and Yield Attributes of Sunflower (Helianthus Annus L.) Grown Under Wastewater Irrigation

The present work focused on the elimination of heavy metals (Pb^+ 2, Ni^+ 2,and Cr^+ 6) and excess potassium from industrial wastewater by using organic soil amendments (biochar, chitosan beads and chitosan beads-infused biochar) through adsorption. Two sets of experiments were performed i.e., (i) adsorption experiment to check the heavy metal adsorption capacity of chitosan beads (ii) pot experiment to check the influence of different soil amendments comprising of biochar and chitosan beads (magnetic and non-magnetic) on growth, physiological, biochemical and yield attributes of sunflower receiving waste water irrigation. The atomic absorption spectrophotometry and XRD revealed that the most significant results were achieved with magnetic chitosan beads for the eradication of Pb^+ 2, Ni^+ 2, K⁺ and Cr^+ 6. In pot experiment, more pronounced results regarding plant physiological (as membrane stability index, relative water content, and photosynthetic pigments), absolute growth and yield attributes were noticed in the plants of magnetic chitosan beads-infused biochar amended soil (MB + BAS) and non-magnetic beads-infused biochar amended soil (NMB + BAS)under non-diluted wastewater and diluted wastewater irrigation. FTIR spectra reveal distinct functional group complexation with metal ions in leaves and roots. Roots were traced to have metal complexation with C–O and C = O groups, while O–H groups were predominating in leaves for metal binding. In comparison to other soil amendments, the application of MB + BAS exhibited a noteworthy decrease in stress-associated molecules, including proline and malondialdehyde content. Hence, this study suggest that chitosan beads-infused biochar might be an effective approach for mitigating metal stress in plants and improving the crop growth.