Reduced dry olive residue phytotoxicity in the field by the combination of physical and biological treatments

Abstract

Olive oil extraction generates large amounts of olive mill residues (DOR) which may be used as organic fertilizer. The influence of a combination of physical fractionation and saprobe fungal incubation on the phytotoxicity of DOR was studied. The physical fractions of DOR, obtained following extraction using ethyl acetate (EDOR) and wa- ter (ADOR) were less phytotoxic than DOR with respect to the shoot dry weight of to- mato. There was no relationship between the total phenol content of the different DOR physical fractions and their phytotoxicity. The saprophytic fungus Coriolopsis rigida reduced DOR and ADOR phytotoxicity and eliminated the phytotoxicity of EDOR. However, unlike the physical treatments of DOR, the decrease in the phenol content of EDOR and ADOR caused by C. rigida was closely paralleled to the decrease in their phytotoxicity. After 30 days of incubation, C. rigida was able to eliminate the phytotoxicity of EDOR on tomato plants grown in the field.