Abstract

Aqueous ozone (O_3(aq)) solutions were applied to the rockwool substrate of hydroponically cultured tomato and cucumber plants. Single applications of high concentration solutions (0, 5, 10, 15, 20 mg/L), as well as repeated application of lower concentration solutions (0, 2, 4, 6 mg/L), had no impact on leaf area and shoot dry weight accumulation. Repeated O_3(aq) applications were also applied to cucumber plants inoculated with Pythium aphanidermatum.  Pathogen levels were significantly reduced in all treatments containing O_3(aq). The reduction in pathogen numbers did not necessarily affect plant productivity.

Key words: Pythium aphanidermatum, irrigation water reuse, oxygenation, tomato, cucumber, rockwool, hydroponics, phytotoxicity.