Combination of phosphorus mobilizing and solubilizing fungi with phosphoric rocks and volcanic materials for growth promotion of lettuce (Lactuca sativa L.) plants

Abstract

Arbuscular mycorrhizal fungi (AMF) increase the uptake of soluble phosphates, while phosphorus solubilizing fungi(S) promote the solubilization of insoluble phosphate complexes, together benefiting plant nutrition. The use of theseorganisms in combination with minerals or rocks that provide nutrients is another alternative to maintain crop productivity.The objective of this work was to combine AMF and S with pyroclastic materials (ashes and pumicites) from the Puyehuevolcano and phosphoric rocks (PR) from the Río Chico Group (Chubut) and to evaluate the performance of these mixturesas substrates for potted production of Lactuca sativa. To formulate the substrates, a mixture of Ter-rafertil® with asheswas used as a base. Penicillium thomii was the S and spores of the fungus Rhizophagus intraradices (AEGIS® Irriga)served as the source of AMF. Various combinations of microorganisms and the addition or not of RP were evaluated. Thetreatments were: (1) substrate; (2) substrate + AMF; (3) substrate + S; (4) substrate + AMF + S; (5) substrate: PR; (6)substrate: PR + AMF; (7) substrate: PR + S, and (8) substrate: PR + AMF + S. There were 3 replicates per treatment. Theparameters evaluated were total and assimilable P content in the substrate, P in plant tissue and dry biomass. All of themwere significantly higher in the plants grown in the substrate added with PR and inoculated with S and AMF. This workconfirms that the S/AMF combination with volcanic ashes from Puyehue and PR from Grupo Río Chico formulated witha commercial substrate promote the growth of L. sativa. Thus, it is possible to increase the added value of geomaterialsof national origin.