title: Effects of ozone on crops in north-west Pakistan.
abstract: Although ozone is well-documented to reduce crop yields in the densely populated Indo-Gangetic Plain, there is little knowledge of its effects in other parts of south Asia. We surveyed crops close to the city of Peshawar, in north-west Pakistan, for visible injury, linking this to passive measurements of ozone concentrations. Foliar injury was found on potato, onion and cotton when mean monthly ozone concentrations exceeded 45 ppb. The symptoms on onion were reproduced in ozone fumigation experiments, which also showed that daytime ozone concentrations of 60 ppb significantly reduce the growth of a major Pakistani onion variety. Aphid infestation on spinach was also reduced at these elevated ozone concentrations. The ozone concentrations measured in April-May in Peshawar, and used in the fumigation experiment, are comparable to those that have been modelled to occur over many parts of south Asia, where ozone may be a significant threat to sensitive crops.
authors.affiliation: Environment Department, University of York, York YO10 5DD, UK.
authors.forename: Muhammad Nauman
authors.initials: MN
authors.lastname: Ahmad
authors.forename: Patrick
authors.initials: P
authors.lastname: Büker
authors.forename: Sofia
authors.initials: S
authors.lastname: Khalid
authors.forename: Leon
authors.initials: L
authors.lastname: Van Den Berg
authors.forename: Hamid Ullah
authors.initials: HU
authors.lastname: Shah
authors.forename: Abdul
authors.initials: A
authors.lastname: Wahid
authors.forename: Lisa
authors.initials: L
authors.lastname: Emberson
authors.forename: Sally A
authors.initials: SA
authors.lastname: Power
authors.forename: Mike
authors.initials: M
authors.lastname: Ashmore
mesh_terms: D000383:Agriculture / Q000706:statistics & numerical data; D000393:Air Pollutants / Q000633:toxicity*; D000397:Air Pollution / Q000706:statistics & numerical data; D002947:Cities; D018556:Crops, Agricultural / Q000187:drug effects* / Q000254:growth & development; D004784:Environmental Monitoring; D060434:Herbivory; D010126:Ozone / Q000633:toxicity*; D010154:Pakistan
chemical_list: D000393:Air Pollutants; D010126:Ozone