Effect of Ambient Gases on Respiration of Soil Supporting Four Crops in Central Saudi Arabia

This study was conducted at four localities (Maseef, Naseem, Oleya and Industrial City) in Riyadh city, KSA to determine the effect of increased tropospheric gases on responses of in situ soil respiration (Rs) of wheat (Triticum aestivum L. cv. Giza 68), broad bean (Vicia faba L. cv. Lara), kidney bean (Phaseolus vulgaris L. cv. Giza 3) and pea (Pisum sativum L. cv. Perfection) rhizosphere soil. These plants were grown to a full-season in pots to recieve four air quality localities treatments. Daily mean of O3, SO2, NO2 and CO2 concentrations were recorded by portable gas analyzers in the center of studied localities. The Rs values were measured monthly before seed germination, during all growth stages and after harvesting (October, December, February, April and June) at three times during the day (morning, noon and afternoon) for each stage. The maximum values recorded for O3 in mid June, 2007 were 39, 77, 95 and 166 nL L-1, in Maseef, Naseem, Olea and Industrial City localities, respectively. Significant decreases in Rs were observed for all polluted localities in compared Maseef site (less polluted). The greatest decreases in Rs were found at Industrial City followed by Naseem and Oleya. More reductions in Rs were observed for the Industrial City treatments during flowering and grainfill stages, while normal respiration at Maseef area was recorded. This study concluded that O3 injury can reduce the Rs by decreasing the activities and reactions in soil supporting plants

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 KS