Keywords: ozone, cotton, photosynthesis, chlorophyll fluorescence, lipid peroxidation, Rubisco activity, plant growth, yield, Egypt, photoassimilation, carbon dioxide
CO2 photoassimilation, chlorophyll fluorescence, lipid peroxidation and yield in cotton (Gossypium hirsutum L. cv Giza 65) in response to O3
Over the recent years, convincing evidence has emerged of both a decrease in stratospheric ozone (O3) and an increase in tropospheric O3 concentration. There is an intimate relationship between O3 and photosynthesis (A), which is ultimately linked to plant growth and yield. Photosynthetic response, chlorophyll fluorescence, Rubisco activity, lipid peroxidation and yield of an Egyptian cultivar of cotton (Gossypium hirsutum L. Cv. Giza 65) in response to fumigation with 70 nl l-1 O3 for 14 days, 10 hd-1 (8:00–18:00 local time) were investigated. Photosynthetic rate (A), stomatal conductance (gs), the ratio between variable and maximum fluorescence (Fv/Fm) and total Rubisco activity were reduced by 18%, 23%, 11% and 34%, respectively, and chlorophyll content, growth and yield of the plant were also reduced substantially by O3 exposure. O3-induced reductions in A were related to declines in growth and yield. Since exposure to O3 concentration typical of level of the pollutant recorded in Egypt reduced A, growth and yield of the species under investigation, reductions in A may be occurring in other important crops in Egypt.