Influence of atmospheric pollutants on agriculture in developing countries: a case study with three new wheat varieties in Pakistan.

The performance of three wheat varieties (Inqilab-91, Punjab-96, Pasban-90) was investigated in open-top chambers with charcoal-filtered air (FA), unfiltered air (UFA) and unchambered field plots (AA) during the 2003-2004 season at a semi-urban site in Lahore, Pakistan. The 8-h daily mean O(3), NO(2) and SO(2) concentrations in UFA and AA remained 72, 28 and 15 ppb, respectively. Plants grown in UFA and AA showed stunted growth and accelerated rate of leaf senescence with pronounced reductions in stomatal conductance (7-24%), net photosynthetic rate (20-22%) and photosynthetic efficiency (9-17%) compared with FA plants. A mid-season harvest of 10-week-old plants revealed reduced plant fresh (14-37%) and dry weights (15-43) in UFA compared to FA counterparts. Grain yield recorded after a full season of growth was drastically reduced in UFA with 43% for Pasban-90, 39% for Punjab-91 and 18% for Inqilab-91 compared with FA control plants. Nutritional quality of seeds was also significantly reduced in UFA and AA with respect to starch, but not in protein and vitamin-E contents when compared with FA plants. This investigation carried out in a major developing country of southeast Asia has shown alarming effects of atmospheric pollutants on both yield and nutritional quality of an important cereal crop that needs urgent attention to maintain the agricultural systems with parallel efforts to reduce the emissions in the region.