Revolutionizing lead remediation: sorghum-mediated immobilization enhanced by plant growth-promoting rhizobacteria and zeolite

Abstract

Lead, a persistent hazardous heavy metal, poses severe health risks, affecting human systems and disrupting plant functions. Plant growth-promoting rhizobacteria (PGPR) and zeolite offer promising solutions. In a pot experiment, sorghum responded positively to integrated PGPR and zeolite application in lead-contaminated soil. Lead nitrate at varying concentrations was spiked three weeks before sowing, with zeolite added at 6% of soil. The combined application effectively reduced lead toxicity, immobilized lead in the soil, and limited its movement to above-ground plant parts. The integrated use of PGPR and zeolite in lead contamination of 0, 600 and 1200 mg kg^-1 soil, enhanced the germination by 25, 50, 64%, shoot length by 23, 26, 32%, shoot fresh weight by 31, 28, 39%, shoot dry weight by 22, 31, 34%, root length by 60, 78, 125%, root fresh weight by 36, 28, 41% and root dry weight by 26, 41, 59, respectively, over control. Moreover, the upsurge in grain yield pot-1 by 40, 54, 58%, biological yield pot^-1 by 39, 42, 51% and SPAD value by 15, 24, 31% was found as compared with control under 0, 600 and 1200 mg kg^-1 of lead, respectively. Whereas PGPR and zeolite decreased the lead concentration in the root (32 and 24%), shoot (32 and 31%) and grain (100 and 75%) over control treatment in 600 and 1200mg kg^-1 soil, respectively. So, PGPR and zeolite proved to be an efficient option for improving the growth and yield of sorghum by immobilization of lead.