Submitted to: American Society of Plant Biologists
Publication Type: Abstract Only
Publication Acceptance Date: 6/21/2005
Publication Date: 7/1/2005
Citation: Flowers, M.D., Fiscus, E.L., Burkey, K.O., Booker, F.L. 2005. Ozone sensitive and resistant lines of snap bean. I. photosynthesis and chlorophyll fluorescence. American Society of Plant Biologists.
Technical Abstract: Widespread areas of crop production are at risk for damage at ambient ozone (O3) concentrations. Past research has not determined the plant mechanisms that cause differences in O3 sensitivity. Therefore, a study was undertaken to examine the effects of O3 on three snap bean (Phaseolus vulgaris) genotypes with known differences in O3 sensitivity. Snap beans were grown in environmentally controlled field chambers admitting 90% of full daily sunlight and containing temperature, relative humidity, and O3 controls. A 4 x 3 factorial design with four O3 treatments and three snap bean genotypes was used. Measurements of photosynthesis and chlorophyll fluorescence were made weekly throughout the growing season and yield data was collected at physiological maturity. A chronic O3 exposure of 60 nmol mol-1 significantly reduced both the photosynthetic capacity and electron transport in the sensitive snap bean genotype. Compared to the 0 nmol mol-1 O3 exposure (control) the 60 nmol mol-1 O3 treatment (high) reduced assimilation, maximum RuBP saturated rate of carboxylation, the ratio of variable fluorescence to maximal fluorescence, and photochemical quenching. Yield was also significantly reduced 77% in high O3 compared to the control. Ozone did not significantly reduce either photosynthetic capacity or electron transport in the two tolerant snap bean genotypes. However, yield was significantly reduced up to 34% in these genotypes when compared with the control. While the cause of the yield differences in the two O3 tolerant genotypes can not be elucidated from the measurements made in this study, further studies with these genotypes may lead to a better understanding of the mechanisms of O3 sensitivity and tolerance.