Physiological and biochemical responses of the ozone (O3)-sensitive pumpkin cultivar (Cucurbita pepo 'Ambassador') to O3 exposure are reported here to determine critical O3 concentrations related to duration of pollutant exposure. Pumpkin plants were exposed to 150 nl l-1 of O3 for 5 h d-1 for 5 d. Gas-exchange, chlorophyll a fluorescence and pigment-content measurements were determined on days 1, 3, 5 for young leaves and days 1, 3, 4 for the mature leaves of control and treated plants. In both young and mature leaves, O3 induced a significant decrease in photosynthetic rate through impacts on stomata and photochemistry. A reduction in PSII photochemistry, photochemical quenching and quantum yield, accompanied by a parallel increase in nonphotochemical quenching was detected. Following O3 treatment the pool of xanthophyll cycle pigments and the de-epoxidation index underwent a significant increase, whereas chlorophylls and β-carotene were less affected. The results showed that most of the parameters were affected by O3 after 1 d of exposure and indicated an overall effect of O3 and days of treatment, irrespective of leaf age.
Ozone exposure affects photosynthesis of pumpkin (Cucurbita pepo) plants
CASTAGNA, ANTONELLA;NALI, CRISTINA;LORENZINI, GIACOMO;SOLDATINI, GIANFRANCO;RANIERI, ANNAMARIA
2001-01-01
Abstract
Physiological and biochemical responses of the ozone (O3)-sensitive pumpkin cultivar (Cucurbita pepo 'Ambassador') to O3 exposure are reported here to determine critical O3 concentrations related to duration of pollutant exposure. Pumpkin plants were exposed to 150 nl l-1 of O3 for 5 h d-1 for 5 d. Gas-exchange, chlorophyll a fluorescence and pigment-content measurements were determined on days 1, 3, 5 for young leaves and days 1, 3, 4 for the mature leaves of control and treated plants. In both young and mature leaves, O3 induced a significant decrease in photosynthetic rate through impacts on stomata and photochemistry. A reduction in PSII photochemistry, photochemical quenching and quantum yield, accompanied by a parallel increase in nonphotochemical quenching was detected. Following O3 treatment the pool of xanthophyll cycle pigments and the de-epoxidation index underwent a significant increase, whereas chlorophylls and β-carotene were less affected. The results showed that most of the parameters were affected by O3 after 1 d of exposure and indicated an overall effect of O3 and days of treatment, irrespective of leaf age.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
