Tropospheric Ozone Effects on the Productivity of Some Crops in Central Saudi Arabia

This study was conducted to evaluate damaging degree of ambient ozone (O₃) levels in certain economically important crops in typical areas of the central KSA (Riyadh). Daily mean ozone concentrations were recorded by portable O₃ analyzers in the center of Batha, Naseem, Oleya and Industrial City, from the beginning of October, 2006 to middle of June, 2007. Maseef area was used as control because it is receiving fewer pollutants (O₃ levels less than 40 nL L^-1). Selected crops grown in pots were exposed to short-term of pollution at defined localities. These crops include Triticum aestivum L. cv. Giza 68 (wheat), Vicia faba L. cv. Lara, (broad bean), Phaseolus vulgaris L. cv. Giza 3 (kidney bean) and Pisum sativum L. cv. Perfection (pea). The exposure indicators of them are length, injury symptoms, biomass and yield. The maximum values of daily O₃ were 125 nL L^-1, 77 nL L^-1, 95 nL L^-1 and 166 nL L^-1, in all the four studied areas, respectively in mid June, 2007. Results showed that the estimated yield losses varied in all four studied areas, being 35, 9, 39 and 46%, respectively for wheat; being 16, 13, 21 and 33%, respectively for broad bean; being 22, 20, 28 and 45%, respectively for kidney bean and being 5, 3, 14 and 30%, respectively for pea. This research recommended that these plant species can be used to give bio-indicator significance to assess ambient ozone impacts of different examined areas in KSA.