Combined use of companion planting and PGPR for the assisted phytoextraction of trace metals (Zn, Pb, Cd)

Abstract

Biomass production and metal accumulation in plant tissue (bioconcentration) are two critical factors limiting the phytoextraction rate. Metal translocation to aboveground organs should be accounted for as the third most important factor, as harvesting of the plant roots is usually economically disadvantageous. These three parameters could be potentially increased with the use of companion planting, a well-known agricultural technique, and inoculation with plant growth–promoting bacteria (PGPB). The aim of the study was to determine whether intercropping and inoculation with endophytic PGPB (Burkholderia phytofirmans PsJNT) can increase the efficiency of phytoextraction of Zn, Pb, and Cd. The study was conducted on Brassica juncea (L.) Czern. “Małopolska” grown in a monoculture or co-planted with Zea mays L. “Codimon” and Medicago sativa L. “Sanditi.” Results show that companion planting and inoculation with rhizobacteria can increase the efficiency of metal phytoextraction, mainly by increasing the yield of dry biomass and the survival rate of plants grown on contaminated soil. We have shown that the simultaneous planting of B. juncea with M. sativa and inoculation with PGPB were the most efficient variants of assisted phytoextraction reaching a recovery of 95% Zn, 90% Cd, and on average about 160% Pb compared with control B. juncea plants grown in monoculture.

Role of Bacillus cereus in Improving the Growth and Phytoextractability of Brassica nigra (L.) K. Koch in Chromium Contaminated Soil

“…Abdollahi et al [ 38 ] research showed that inoculation of PGPR increased the phytoavailability of Cd and Pb and also improved the growth of cabbage varieties. Konkolewska et al [ 39 ] also documented that PGPR increased the rate of heavy metal phytoextraction mainly by increasing the production of dry biomass.…”

A review of green remediation strategies for heavy metal contaminated soil

“…With microbial assistance, metal extraction or stabilization efficiencies can be enhanced substantially. For instance, the PGPB Burkholderia phytofirmans inoculation enhanced the Brassica juncea phytoextraction efficiency of Zn, Cd and Pb by 37%, 21% and 10%, respectively (Konkolewska et al, 2020). Sunflower inoculated with Bacillus proteolyticus accumulated 40% less Cd and 20% less Pb in aboveground tissues, suggesting enhanced phytostabilization induced by PGPBs (Radziemska et al, 2020;Saran et al, 2020).…”

Evaluation of the PGPR Capacity of Four Bacterial Strains and Their Mixtures, Tested on Lupinus albus var. Dorado Seedlings, for the Bioremediation of Mercury-Polluted Soils

“…In this sense, it is worth highlighting the so-called Plant Growth Promoting Rhizobacteria (PGPR), highly efficient to increase plant growth and increase their tolerance to biotic and abiotic factors. This particular type of phytoremediation using PGPRs in combination with plants is called phytorhizoremediation [15]. The success of this technique lies in the fact that the rhizosphere is an interface in which plants and microorganisms establish complex and varied molecular relationships, which involve the nutrients transfer, as well as specific interactions mediated by the release of signaling molecules from plant roots [16].…”