Sunflower (Helianthus annuus L., cv. NK894) seedlings, grown hydroponically, were exposed to ozone concentrations of 0.0, 0.1, 0.2, and 0.3 ppm at 60% RH, or 0.0
and 0.3 ppm at 30% and 90% RH, for 6 h/d, for four consecutive days, at ages 15 to 18 days from seeding. Plant...