Effect of Ozone Exposure on Growth, Yield and Isoprene Emission from Tomato (Lycopersicon esculentum L.) Plants

Effect of ozone on three different growth phase of tomato (Lycopersicon esculentum cv. Pusa ruby) crop namely, Early Vegetative Phase (EVP), 30 days old plants; Late Vegetative Phase (LVP), 45 days old plants; and Fruiting Phase (FP), 60 days old plants were exposed to ozone concentrations (75 ppb and 150 ppb) in closed top dynamic chambers for 12 days period. Ozone exposed tomato plants of all the three growth stages exhibited visible injury symptoms as chlorotic spots in variable intensity. Effect of ozone exposure on tomato crop plants was examined with respect to isoprene emission, growth and yield parameters. Enhancement in isoprene emission was observed from ozone exposed tomato plants as compared to unexposed plants. In exposed plants of early vegetative phase isoprene emission was 127% and 187% higher immediately after (within 1 hr) 75 ppb and 150 ppb ozone exposure respectively as compared to unexposed plants. Significant (p≤0.001) reduction in ozone exposed plants shoot length (2 to 10.5%), chlorophyll content (7 to 39%), carotenoids contents (5 to 42%), shoot biomass (upto 44%) and root biomass (8 to 65%) were observed as compared to unexposed plant. It was found that ozone exposure was more detrimental to LVP in comparison to FP and EVP. The results of the study also showed that 150 ppb of ozone exerted more harmful effects on the growth of different growth phases of tomato plants than 75 ppb ozone.