Effect of NaCl on the development of the oil palm vascular wilt fungus, Fusarium oxysporum f. sp. elaeidis.

Abstract

Oil palm Elaeis guineensis Jacq. (Arecaceae) is one of the cash crops that mainly contributes to the gross domestic production of growing countries. This crop is grown worldwide throughout the humid intertropical belt. Its production in Africa is mainly threatened by the telluric fungus Fusarium oxysporum f. sp. elaeidis, causal agent of the oil palm vascular wilt. It has been reported that some environmental factors, such as soil and air salinity, may determine the survival, development and severity of phytopathogenic agents including Fusarium. The purpose of this study was to evaluate the effect of NaCl on growth, reproduction and pathogenic traits of this fungus by measuring mycelium daily growth, mycelium dry weight, sporulation rate, germination rate and number of infectious spores under four NaCl concentrations (0 g.L-1, 2.5 g.L-1, 5 g.L-1 ,10 g.L-1) of culture medium (MM solid medium and Armstrong liquid medium). The results indicated that NaCl reduced the radial daily growth and mycelium dry weight. In addition, the NaCl reduced significantly the sporulation rate and number of infectious spores while increasing the germination rate. Overall, these results indicated the negative NaCl effect on the development and the fitness of this pathogenic fungus. Thus, NaCl inputs appeared to be a potential solution for managing Fusarium oxysporum f. sp. elaeidis in the field, if a good balance between a decrease of disease incidence and yield loss is reached.