AIR-POLLUTION AND ITS IMPACTS ON WHEAT YIELD IN THE PAKISTAN PUNJAB

A study using open-top chambers ventilated with ambient or charcoal-fi ltered air in the vicinity of Lahore, Pakistan, has demonstrated a red uction of 46.7% and 34.8% in the grain yield for two cultivars of wint er wheat (Triticum aestivum L.). The 6-h daily mean O-3 concentrations were 25-45 nl litre(-1) and on the basis of experience in North Ameri ca and Europe, reductions in yield in the present study are substantia lly greater than might be predicted The reasons for this discrepancy a re discussed, together with implications for the suitability of a simp le, relatively cheap, open-top chamber system for developing-country s tudies on the effects of air pollution on crops.