Wastewater grown microalgal biomass as inoculants for improving micronutrient availability in wheat

Abstract

An investigation was undertaken to evaluate the potential of two sewage grown microalgal formulations (consortia of native microalgae mixed with vermiculite: compost as carrier) in enhancing the soil micronutrient availability and uptake in wheat crop. Significantly higher available zinc (Zn), iron (Fe), copper (Cu) and manganese (Mn) content were recorded in soil samples from treatments belonging to microalgal consortia inoculation, as compared to uninoculated treatments, at both mid and harvest stage of wheat crop. A significant enhancement of 35.1 - 51% in organic carbon content was recorded in microalgal consortia inoculated treatments over control. Highest values were observed in treatment T5 (75% N + full dose PK + formulation with MC2, comprising native filamentous microalgae (Phormidium, Anabaena, Westiellopsis, Fischerella, Spirogyra). The treatment T4 (75% N + full dose PK + MC1formulation (comprising unicellular green algae -Chlorella, Scenedesmus, Chlorococcum, Chroococcus)showed significantly higher values of dehydrogenase activity. The plants from treatment T5 (75% N + full dose PK + formulation with MC2) recorded 53% higher leaf chlorophyll, as compared to T1 (recommended dose of fertilizer) at mid-crop stage. Microalgal consortia inoculated treatments also showed 37.3 - 48.0% increase in grain yield with significantly higher micronutrient (Zn, Fe, Cu and Mn) content in grains, as compared to control. A strong positive correlation was recorded between the availability of micronutrients in soil at mid-crop and grain yield. The present study highlighted the promise of wastewater grown microalgal consortia for improving soil micronutrient availability, micronutrient enrichment of wheat grains and enhancing crop productivity.