Influence of gasoline emissions on tomato fruit rot by two fungi in tropical ambient conditions

Abstract

Background The release of pollutant gases into the atmosphere as a result of anthropogenic activities exert effect on biological systems at many levels. Combustion engines such as those in vehicles and power generators pollute the air with emissions from their exhausts. The gases released which are oxides of carbon, nitrogen; sulphur and particulate matter have effect on living things in the immediate environment. Up to 25% of harvested fruits and vegetables are lost mainly due to microbial activities before consumption. Disease development in ripe tomato fruit (host) by two of its fungal pathogens in the presence of generator emissions is presently being studied. Results Treatment produced variable effects depending on the fungus and the route of infection. For Rhizopus stolonifer coated and Fusarium oxysporum wound inoculated fruits, significant disease reduction was noticeable in the later days of storage, specifically from day 11. Fruits coated with F. oxsporum spores without wounding however, rotted more with gasoline emissions treatment also noticeably at the later period of storage. Long exposures caused greater rot reduction where disease was reduced and more severe rot where disease was enhanced. Rhizopus infected fruits were best preserved for 14 days by 40 min exposure while wound inoculated Fusarium infected fruits were best preserved by 45 min exposure. Disease reduction was 40–50% in both types of infection. Conversely, disease was most aggravated by about 50% by 45 min exposure of unwounded Fusarium infected fruits. Other exposures also caused increased rotting by about 5–35%. Conclusions The results demonstrate that air pollution by fumes from generators may under certain host–pathogen conditions be advantageous in prolonging postharvest life of ripe tomatoes, while at other times could be devastating when fruits are subsequently stored or marketed at tropical ambient temperature. The advantage, however, outweighs the negative effects.