The Exposure of Wheat (Triticum aestivum L. cv. Giza 68) Plants Grown in Filtered and Nonfiltered Open-Top Chambers to Atmospheric O3 and CO2

Increasing of gaseous concentrations have prompted concerns about further impacts such as changes may have on the earth’s food and fiber crops. Interactive effect of ozone (O3) and carbon dioxide (CO2) on the yield, yield components and grain composition of wheat (Triticum aestivum L. cv. Giza 68) was investigated in 2004 and 2005 at a farm far from Cairo 85km eastern of Egypt. Plants were grown from the three-leaf stage until harvest in open-top chambers (OTC’s) ventilated with charcoal filtered air (CF) at 350 µL CO2 L-1; CF + 200 µL CO2 L-1; non-filtered air (NF) and NF + 200 µL CO2 L-1 with two levels of drought. Mean 7-hours d-1 of O3 concentrations in the NF was higher in hot months being 40 nLL-1, while CO2 concentrations were higher only in November being 400 µLL-1. The effect of nonfiltered chambers was more pronounced in comparison with filtered chambers. Grain yield decreased with increasing seasonal mean O3 concentration as a result of reductions in the weight of individual grains and in the number of grains per head, while CO2 could decrease their effect. With increasing O3 small or no changes were observed in protein, but carbohydrates and lipids concentrations had much changes between treatments. The effect of O3 on total amino acids content of seed storage proteins caused the appearance of valanine, methionine, isoleucine, serine, tyrosine, phenyalalnine, lysine and arginine. The exposure of plant to O3 induced the disappearance of polypeptide with high molecular weight (200 163) at relative flow (Rf 0.069 0.11) in comparison to control. This study concluded that the loss of grain amino acids production caused by a certain yield loss by O3