Effects of ozone on the yield of spring wheat triticum aestivum l. cultivar albis grown in open top field chambers

Fuhrer, J.; Egger, A.; Lehnherr, B.; Grandjean, A.; Tschannen, W.

Environmental Pollution 60(3-4): 273-290


ISSN/ISBN: 0269-7491
Accession: 007281275

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Spring wheat (Triticum aestivum L., cv. Albis) was grown in the field at a site located in central Switzerland, and exposed to chronic doses of ozone (O3) in open-top chambers to study impacts on yield. The experiment was carried out in 1986, 1987 and 1988. The treatments used included charcoal-filtered air (CF), non-filtered air (NF) and non-filtered air to which constant amounts of O3 (two levels, O3-1 and O3-2) were added daily from 09.000 until 17.00 local time. Mean solar radiation-weighted O3 concentrations during the fumigation period were in the range 0.016-0.022 .mu.l litre-1 (CF), 0.036-0.039 .mu.l litre-1 (NF), 0.057-0.058 .mu.l litre-1 (O3-1, used in 1987 and 1988 only) and 0.078-0.090 .mu.l litre-1 (O3-2). Fumigation was maintained from the three-leaf stage until harvest. Ambient plots were used as a reference. Plant characteristics examined included straw yield, grain yield, number of grains per head, number of heads per surface area, weight of individual grains and harvest index (ratio of grain weight to total dry weight). Pollutant concentrations and other environmental parameters were monitored continuously inside and outside the chambers. In 1986 and 1987, enclosure mostly increased the values of different parameters, while in 1988, they were decreased. The negative enclosure effect was due to extremely turbulent winds, which caused lodging inside the chambers. In all 3 years, increasing O3 concentration negatively affected the parameters studied, except for the number of heads per surface area, which showed no treatment response. Grain yield showed a very sensitive response to O3. The effect of O3 on grain yield was due to an effect primarily on grain size and secondarily on grain number. The relative response of grain yield to O3 was similar in all 3 years, despite year-to-year differences in climatic conditions and enclosure effects. The analysis of the data for combined years revealed an increase of about 10% in grain yield due to air filtration. The corresponding increase in straw yield was only about 3.5%. Exposure-response models were developed for individual years and combined years. It is concluded that, in the study area, ambient O3 may affect grain yield in spring wheat.