Assessment of yield losses in tropical wheat using open top chambers

The present study deals with the evaluation of effects of ambient gaseous air pollution on wheat (Triticum aestivum L. var. HUW-234) growing in a suburban area situated in eastern Gangetic plain of India, using open top chambers. Fight hourly air monitoring was conducted for ambient concentrations of SO2, NO2 and O-3 in filtered chambers (FCs), non-filtered chambers (NFCs) and open plots (OPs). Various morphological, physiological and biochemical parameters were assessed during different developmental stages and finally yield parameters were quantified at the time of harvest. Mean concentrations of SO2, NO2 and O-3 were 8.4, 39.9 and 40.1 ppb, respectively during the experiment in NFCs. Concentrations of SO2, NO2 and O-3 reduced by 74.6%, 84.7% and 90.4%, respectively in FCs as compared to NFCs. Plants grown in FCs showed higher photosynthetic rate, stomatal conductance, chlorophyll content and Fv/Fm ratio as compared to the plants in NFCs and OPs. Lipid peroxidation, proline, total phenol and ascorbic acid contents and peroxidase activity were higher in plants grown in NFCs. There were improvements in morphological parameters of plants growing in FCs as compared to those in NFCs and OPs. Yield of plants also increased significantly in FCs as compared to those ventilated with ambient air (NFCs) or grown in OPs. During the vegetative phase, NO2 concentrations were higher than O-3, but O-3 became dominant pollutant during the time of grain setting and filling. The study concludes that O-3 and NO2 are the main air pollutants in the sub-urban areas causing significant yield reductions in tropical wheat plants. (C) 2007 Elsevier Ltd. All rights reserved.