RESPONSES OF SPRING WHEAT (TRITICUM-AESTIVUM L) TO OZONE PRODUCED BY EITHER ELECTRIC-DISCHARGE AND DRY AIR OR BY UV-LAMPS AND AMBIENT AIR

The aim of the present study was to examine if ozone produced similar effects on spring wheat growth with and without small amounts of nitro gen oxides. Two methods were used to produce ozone: the first method c onsisted of dry pressurized air fed to an electric discharge generator generating the byproducts, N2O5 and N2O, the second method consisted of ambient air fed to UV-lamps. Two spring wheat cultivars (Triticum a estivum L. cvs Minaret and Eridano) were exposed in small open-top cha mbers to charcoal-filtered air, non-filtered ambient air, and non-filt ered ambient air with the addition of ozone for 8 h (0900 to 1700 h) d aily, for five weeks. Plants were harvested every week. The growth of Minaret was shown to be more sensitive to O-3 than that of Eridano. Le af senescence increased with increasing ozone level in both cultivars. The total above-ground biomass dry weight decreased with increasing o zone concentration in Minaret, but not in Eridano. The Minaret plants reacted with more damaged leaf dry weight and inhibition of growth whe n O-3 was produced by UV-lamps than when O-3 was produced by air fed t o an electric discharge generator. This could be explained by more nit rogen content per plant but not by increased nitrogen concentration in plant tissue in plants exposed to increased O-3 and small amounts of incidental nitrogen oxides. Copyright (C) 1996 Elsevier Science Ltd