Growth promotion of tomato and radish plants by solar UV radiation reaching the Earth's surface

Abstract

The effect of natural solar UV radiation on the growth of tomato and radish plants was studied using polyvinylchloride films with different UV transmissions. The growth (fresh and dry weights) of tomato plants exposed to UVA (400-320 nm) radiation (UVC-320 film, transmission above 320 nm) was greater than that of plants exposed to no UV radiation (UVC-400 film, transmission above 400 nm) or to mainly near-UV radiation (400-300 nm; including UVA (400-320 nm) and the longer wavelength region within the UVB (320-280 nm); UVC-290 film, transmission above 290 nm). Furthermore, the growth promotion of tomato and radish plants on exposure to UVA has associated with an increase in chlorophyll content and photosynthetic activity. Dark respiration of tomato and radish plants was also promoted by radiation (near-UV and UVA region) through UVC-290 and UVC-320 films. Radiation with UVA delayed the senescence of tomato leaves.