Exposure of oats, Avena sativa L., to filtered and unfiltered air in open-top chambers: effects on grain yield and quality.

Field grown oats, Avena sativa L. cv Vital, were exposed to filtered and unfiltered air from anthesis until harvest in open-top chambers at a site in south-west Sweden. Ambient plots were used to study the influence of the chamber itself. With the exception of the number of grains per panicle, which was significantly higher in the charcoal-filtered treatment, no significant filtration effects were obtained for any of the plant growth parameters studied), i.e. grain yield, number of panicles per square metre, 1000-grain weight, straw yield and harvest index.) The chamber had a significant negative effect on grain yield, 1000-grain weight and straw yield. None of the yield quality parameters that were measured, such as crude protein content, crude fibre content, fat content, volume weight of the grain and water content of the grain at harvest, were significantly influenced by either air filtration, or the presence of the chamber. The chlorophyll content of the flag leaves was higher in the charcoal-filtered treatment than in the non-filtered and ambient air treatments towards the end of the experiment, indicating that filtering of the air delayed senescence. The decline of the shoot area after the onset of plant senescence proceeded faster in both chamber treatments. The faster development in the chamber was explained by the faster accumulation of thermal time in the chamber.