RESUMO
In the center of the Nile Delta in Egypt, the Kitchener drain as the primary drainage discharges about 1.9 billion m3 per year of water, which comprises agricultural drainage (75â¯%), domestic water (23â¯%), and industrial water (2â¯%), to the Mediterranean Sea. Cadmium (Cd) stands out as a significant contaminant in this drain; therefore, this study aimed to assess the integration of biochar (0, 5, and 10 ton ha-1) and three PGPRs (PGPR-1, PGPR-2, and PGPR-3) to alleviate the negative impacts of Cd on sunflowers (Helianthus annuus L.) in saline-alkali soil. The treatment of biochar (10 ton ha-1) and PGPR-3 enhanced the soil respiration, dehydrogenase, nitrogenase, and phosphatase activities by 137â¯%, 129â¯%, 326â¯%, and 127â¯%, while it declined soil electrical conductivity and available Cd content by 31.7â¯% and 61.3â¯%. Also, it decreased Cd content in root, shoot, and seed by 55.3â¯%, 50.7â¯%, and 92.5â¯%, and biological concentration and translocation factors by 55â¯% and 5â¯%. It also declined the proline, lipid peroxidation, H2O2, and electrolyte leakage contents by 48â¯%, 94â¯%, 80â¯%, and 76â¯%, whereas increased the catalase, peroxidase, superoxide dismutase, and polyphenol oxidase activities by 80â¯%, 79â¯%, 61â¯%, and 116â¯%. Same treatment increased seed and oil yields increased by 76.1â¯% and 76.2â¯%. The unique aspect of this research is its investigation into the utilization of biochar in saline-alkali soil conditions, coupled with the combined application of biochar and PGPR to mitigate the adverse effects of Cd contamination on sunflower cultivation in saline-alkali soil.