IMPACT OF OZONE ON SEED YIELD AND QUALITY AND SEEDLING VIGOR 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, yi eld parameters, seed quality and seedling vigour were examined using p urpose-designed chambers that enabled the inflorescences to be exposed separately from the vegetative organs. Exposure of cv. Libravo signif icantly reduced seed number per plant, seed weight per pod and per pla nt, 1000 seed weight, the oil, protein and soluble carbohydrate conten ts of the seed and seedling vigour. In contrast, no significant effect s of exposure were observed at final harvest in cv. Tapidor, largely b ecause increases in the numbers and dry weight of seed enabled the pla nts 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 o f reproductive sites and the implications of the observed effects on s eed quantity and quality for field-grown plants are discussed.