Effect of cornstalk biochar on phytoremediation of Pb-contaminated soil by females and males of Populus deltoids

Soil pollution with lead (Pb) has become a serious global concern, adversely affecting the forest ecosystem. This study was conducted to study the corn straw biochar effects on the remediation efficiency of Pb contaminated soil using Populus deltoids. P. deltoids female and male seedlings were exposed to 900 mg kg-1 soil spiked soil amended with corn straw biochar at 5% (v/v) for 90 days. Pb stress significantly decreased the growth and physiological parameters of both sexes. Females exhibited a higher Pb uptake, accumulation and translation, while males exhibited accumulation of more Pb in root and stem, and elevated anti-oxidative capacity. Biochar addition alleviates the Pb toxicity to P. deltoids in both sexes by immobilizing Pb ion in soil, reducing Pb uptake and translation by P. deltoids, promoting nutrients uptake and plant growth, and improving the diversity and stability of soil bacteria community. Under Pb stress, the metal-resistance microorganisms significantly increased, such as the abundance of Bacteroidetes in females, the abundance of Actinobacteria, Firmicutes and Planctomycetes in males. In brief, the males under biochar addition were promising candidates for phytoremediation of Pb contaminated soil. Our findings provided new insights into mechanisms underlying sexually differential responses to Pb stress under biochar amended.