(344) Effects of Ozone-treated Irrigation Water on Vegetative Growth of Chrysanthemum

An experiment was initiated in June and Aug. 2004 to determine affects of ozonated fertilizer–injected water on plant growth of chrysanthemum ( Chrysanthemum × morifolium T. de Romatuelle `Covington'). Aliquots (20 L) of reverse osmosis water were amended with 0, 50, and 300 mg·L -1 N (21N–3.1P–5.8K) water-soluble fertilizer and exposed to ozone (O 3 ) gas for 0, 30, 60, or 120 s at a flow rate of 300 mL/min. Containers were sealed and allowed to set for 15 min for O 3 diffusion. Treated water was used to irrigate plants. Plants were in 10.2-cm pots and grown until floral initiation. Plants were harvested on 12 Aug. 2004 or 24 Nov. 2004. Growth index (height x canopy width × canopy width in a perpendicular direction/3), and shoot and root dry masses were determined. Interactions between fertility concentration and ozone exposure rates were nonsignificant ( P ≤ 0.05). Significant main effect differences occurred in growth index and shoot/root dry masses in response to fertilizer concentrations, but growth measures were not affected by ozone exposure. Peak ozone concentrations in fertilizer-injected irrigation water averaged 0.21 mg·L -1 O 3 (120 s exposure at 300 mL·L -1 ) after 15 min diffusion time. At 20 min diffusion times, ozone levels dropped to 0 mg·L -1 . No gross morphological differences or obvious necrosis typical of ozone damage on chrysanthemum occurred at any O 3 exposure level. No observable nutritional deficiencies were noted. Vegetative growth of chrysanthemum was not directly injured by irrigation water that was exposed to ozone gas for 0 to 120 s at a 300 mL/min flow rate.