[Isolation, screening of zinc solubilizing microorganisms and its application in low zinc calcareous soil]

Inoculating zinc solubilizing microorganisms (ZSMs) is considered as a promising strategy for increasing Zn phytoavailability in soils with low Zn availability. In present study, we screened six strains of ZSMs from rhizosphere of green manure crop, including three strains of fungi, Talaromyces purpureogenus, Talaromyces pinophilus, and Penicillium amestolkiae, and three strains of bacteria, Cellulosimicrobium funkei, Isptericola cucumis and Streptomyces canus. We conducted a pot experiment of Bok choy inoculated with different ZSMs to analyze the Zn content in shoots and roots, and compared the Zn solubilizing effect of ZSMs. The results showed that Zn content in the roots and leaves of Bok choy of treatments inoculated with ZSMs were increased by 15%-44% and 27%-62%, respectively, and that soil DTPA-Zn concentration were increased by 52%-359%. The treatment inoculated with P. amestolkiae had the best effect. ZSMs significantly enhanced root uptake of Zn and foliar Zn content through increa-sing DTPA-Zn by mobilizing soil Zn by transformation of moderately available Zn (Zn bounded with manganese oxide and Zn strongly bounded with organic matter) to available Zn (exchangeable fraction, Zn bounded with carbonate, and Zn bounded with loose organic matter). The screened Zn mobilizing fungi averagely enhanced soil Zn phytoavailability and leaf Zn content by 240% and 46%, showing superior mobilizing ability than screened bacteria. P. amestolkiae significantly increased Zn content of soil and plant, thus it could be a promising potential microorganism as biofotification agent.