AUTOTOXICITY OF DECAYING TOMATO RESIDUES AFFECTS SUSCEPTIBILITY OF TOMATO TO FUSARIUM WILT

G. Bonanomi, G. Del Sorbo, S. Mazzoleni, F. Scala

Abstract


Fusarium oxysporum f.sp. lycopersici (FOL) induces wilting in tomato plants (Lycopersicon esculentum). This disease causes large losses and it increases when practices include monoculture or limited crop rotation. Under these conditions, large quantities of tomato plant residues decompose in the field and may affect growth of tomato and FOL and their interactions. Here we show that undecomposed tomato residues are phytotoxic in laboratory and greenhouse bioassays and that leaves are more phytotoxic than roots. During decomposition, phytotoxicity of leaves and roots decreases under aerobic conditions, but increases under anaerobic conditions. On the contrary, FOL radial growth and hyphal density are increased by undecomposed leaves and roots, but decreased with aerobically decomposed plant material. Tomato wilting caused by FOL increased when the soil was amended with undecomposed leaves. Our study shows that, under controlled conditions, undecomposed tomato residues affect the growth of tomato (autotoxic effect) and FOL (substrate effect), by causing an increase in incidence of the disease.

Keywords


aerobic-anaerobic decomposition; Fusarium oxysporum f.sp. lycopersici; phytotoxicity; soil-borne pathogens

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DOI: http://dx.doi.org/10.4454/jpp.v89i2.746

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EDIZIONI ETS, Pisa, Italy