Fertilizing Potentiality of Fungal-Treated Olive Mill Solid Waste to Improve Some Growth and Physiological Parameters of Vicia faba L.

The main objective of the present work is to biodegrade the phenols content of olive mill solid waste by a locally isolated fungus under optimized culture conditions and study the effect of the crude olive mill solid waste (OMSW), fermented olive mill solid waste (FOMSW), as well as the residue of water extracted olive mill solid waste (ROMSW) on some growth and physiological biomarkers of Vicia faba. Aspergillus tamarii was the most efficient fungus of ten isolated fungi, where it completely (100%) degraded the phenolic contents of OMSW under the optimized culture conditions. Data showed that applying FOMSW and ROMSW resulted in a significant alleviation of OMSW adverse effects on plant shoots and roots, chlorophylls content, chlorophyll stability index, quantum yield of PSII (Fv/Fm), carbohydrates and protein content as well as the macro-elements K, P, Mg and Ca content. This improvement was increased with increasing concentrations of ROMSW, while it increased up to 4% of FOMSW. Even as the crude OMSW negatively affect the growth and physiological attributes of the tested plant, all treatments stimulated them. It seems that detoxification of OMSW either by A. tamari or water resulted in a marked reduction of phenolics and rising in pH that might improve the soil characteristics and allows a secure and efficient dumping of OMSW.