J. Bender et al., RESPONSE OF CELLULAR ANTIOXIDANTS TO OZONE IN WHEAT FLAG LEAVES AT DIFFERENT STAGES OF PLANT DEVELOPMENT, Environmental pollution, 84(1), 1994, pp. 15-21
The effect of ozone (O-3) on growth, yield and foliar antioxidants of
spring wheat (Triticum aestivum L. cv. Turbo) was investigated in 1990
and 1991 in Braunschweig, Ger many. Plants were gr own full-season in
pots in open-top chambers ventilated with charcoal-filtered (CF) air
to which one or two levels of O-3 were added. Mean 8 h day(-1) (10.00-
18.00 h) O-3 concentrations in the CF and CF + O-3 treatments were 5.9
, 61.2 and 92.5 nl litre(-1) in 1990, and 4.7 and 86.4 nl litre(-1) in
1991. Plants that received the high O-3 level showed symptoms of prem
ature senescence of the oldest leaves and yield reductions in both gro
wing seasons. The contents of ascorbate and glutathione and the enzyme
activities of ascorbate peroxidase and glutathione reductase were mea
sured in symptomless flag leaves in weekly intervals before and after
the beginning of anthesis. Leaf age had a significant effect on all an
tioxidants investigated. The O-3 exposures of about 90 nl litre(-1) in
creased the activity of ascorbate peroxidase and the concentration of
glutathione, but there were no pollutant effects on ascorbate content
and glutathione reductase activity. Measurements of the antioxidant le
vels throughout one day showed no clear indications of diurnal changes
in the antioxidative capacity in wheat flag leaves. The results are d
iscussed in relation to the role of antioxidants in O-3 detoxification
.