PHOTOINDUCED TOXICITY OF PAHS TO THE FOLIAR REGIONS OF BRASSICA-NAPUS(CANOLA) AND CUCUMBIS-SATIVUS (CUCUMBER) IN SIMULATED SOLAR-RADIATION

Simulated solar radiation and natural sunlight can enhance polycyclic aromatic hydrocarbon (PAH) toxicity, previously reported in terms of i nhibited production of Lemna gibba leaves and diminished growth of Bra ssica napus seedling roots, This work has been extended to examine the photoinduced impact of PAHs on the foliar regions of terrestrial plan ts, To carry out these experiments two crop species, B. napus (canola) and Cucumbis sativus (cucumber), were chosen to test the photoinduced toxicity of six PAHs (anthracene, phenanthrene, benzo(a)anthracene, b enzo(a)pyrene, flouranthene, and pyrene), Aqueous solutions containing PAHs were sprayed on the foliage of the plants, It was found that all the PAHs tested had negative impacts on the foliage of the plants and the concentrations that induced toxicity were consistent with those o bserved for inhibition of growth of L. gibba. The impacts were observe d as diminished biomass accumulation, induction of chlorosis, and inhi bition of photosynthesis, It may be concluded from this work that PAHs in rain and surface waters could be harmful to photosynthetic tissues of terrestrial plants. (C) 1996 Academic Press, Inc.