Effects of ambient air pollution on wheat and rice yield in Pakistan

Open-top chambers ventilated with ambient or charcoal-filtered air were used to assess the impact of air pollution on the yield of local cultivars of wheat and rice, at a site on the outskirts of Lahore. At this location, 6-h mean O-3 concentrations reach 60 ppb in certain months, and annual mean NO2 concentrations are 20-25 ppb. The experiments showed significant yield reduction in two successive seasons which ranged from 33% to 46% in wheat and from 37% to 51% in rice. The major yield parameter affected was the number of ears or panicles per plant, although there was also evidence of snail effects on 1000 grain weight and on the number of grains per ear/p anicle. These results have significance in terms of the maintenance of agricultural yields as pollution emissions rise in south and south-east Asia.