EFFECT OF OZONE ON RADISH AND TURNIP UNDER EGYPTIAN FIELD CONDITIONS

EDU was used to assess the impact of ozone on the growth and yield of local varieties of radish (Raphanus sativus L.) and turnip (Brassica rapa L.) at two sites in northern Egypt. At a suburban site, in Alexandria, the growth of radish was significantly increased by application of the anti-ozonant N-[2-(2-oxo-1-imidazolidinyl) ethyl]-N'phenylurea (EDU) but turnip was unaffected. At a rural site, Abbis, 35 km south of Alexandria, the increase in growth of radish caused by EDU was higher than at Alexandria, and a significant increase in the growth of turnip was also found. These effects were consistent with the higher oxidant concentrations measured at Abbis compared with Alexandria. A controlled experiment involving ozone or filtered air treatments in open-top chambers demonstrated protective effects of EDU against ozone of a similar size found in the field, and that EDU had no significant effect on these species in the absence of ozone. This provides confidence that the effects of EDU in the field in Egypt can be ascribed to O-3. The implications of the results for Egyptian agriculture are considered.