Negative effects of fluoranthene on the ecophysiology of tomato plants (Lycopersicon esculentum Mill): Fluoranthene mists negatively affected tomato plants

Cherry tomato plants (Lycopersicon esculentum Mill) were sprayed with fluoranthene and mixture of fluoranthene and mannitol solutions for 30 d. The exposure was carried out in growth chambers in field conditions, and the air was filtered through charcoal filters to remove atmospheric contaminants. Plants were sprayed with 10 μM fluoranthene as mist until they reached the fruiting stage, and the eco-physiological parameters were measured to determine the effects of the treatments. We measured CO2 uptake and water vapour exchange, chlorophyll fluorescence, leaf pigment contents, visual symptoms and biomass allocation. Fluoranthene which was deposited as mist onto leaves negatively affected both growth and the quality of tomato plants, while other treatments did not. The photosynthetic rate measured at saturated irradiance was approximately 37% lower in fluoranthene-treated plants compared with the control group. Other variables, such as stomata conductance, the photochemical efficiency of PSII in the dark, Chl a, Chl b, and the total chlorophyll contents of the tomato leaves were significantly reduced in the fluoranthene-treated plants. Tomato plants treated with fluoranthene showed severe visible injury symptoms on the foliage during the exposure period. Mannitol (a reactive oxygen scavenger) mitigated effects of fluoranthene; thus, reactive oxygen species generated through fluoranthene may be responsible for the damaged tomato plants. It is possible for fluoranthene to decrease the aesthetic and hence the economic value of this valuable crop plant.