|Baker, Neil - BIO SCI UNIV OF ESSEX UK|
Submitted to: Plant Physiology Supplement
Publication Type: Abstract Only
Publication Acceptance Date: July 1, 1998
Publication Date: N/A
Technical Abstract: To date, there is no consensus as to the mechanisms involved in the inhibition of photosynthesis by UV-B, or whether future UV-B levels will inhibit photosynthesis in the field. Pea plants were irradiated throughout development with a high level of UV-B (32 kJ m-2 d-1) in a glasshouse. At all stages of plant development, UV-B had no significant effect on light-saturated CO2 assimilation, Rubisco carboxylation, RuBP regeneration or PSII quantum efficiencies, however adaxial (but not abaxial) stomatal conductance was significantly reduced. Leaf area was significantly reduced in UV-B irradiated plants primarily as a result of an inhibition in cell division and not cell expansion. Field experiments with realistic, modulated UV-B enhancement are essential to accurately predict future plant responses to a depleted ozone layer. A 30 percent increase in ambient UK summer UV-B radiation in the field was found to have no significant effect on pea biomass, leaf area, or any in situ or light-saturated photosynthetic parameter measured, as found in other studies. Clearly future increases in UV-B, associated with predicted levels of ozone depletion, are unlikely to directly affect photosynthetic productivity.