Impact of ozone on seed yield and quality and seedling vigour in oilseed rape (Brassica napus L.)

The effects of a single 6-h exposure of the inflorescences of Brassica napus cvs. Libravo and Tapidor to 100 nLL(-1) ozone on seed yield, yield parameters, seed quality and seedling vigour were examined using purpose-designed chambers that enabled the inflorescences to be exposed separately from the vegetative organs. Exposure of cv. Libravo significantly reduced seed number per plant, seed weight per pod and per plant, 1000 seed weight, the oil, protein and soluble carbohydrate contents of the seed and seedling vigour. In contrast, no significant effects of exposure were observed at final harvest in cv. Tapidor, largely because increases in the numbers and dry weight of seed enabled the plants to compensate for significant initial losses of reproductive sites induced by pollutant exposure. The importance of varietal differences in compensatory flexibility in response to pollutant-induced losses of reproductive sites and the implications of the observed effects on seed quantity and quality for field-grown plants are discussed.