An in vivo analysis of the effect of SO2 fumigation on photosynthesis in Zea mays.

Sarah Price, Steve P. Long

Research output: Contribution to journalArticlepeer-review

Abstract

Fumigation of leaves with SO2 can reduce the capacity for photosynthetic CO2 uptake even in the absence of visible symptoms of damage. In vitro studies suggest that this invisible injury to intact leaves could be affected by damage to each of the main stages in the photosynthetic process. Reduced stomatal apertures may also reduce photosynthesis following SO2 fumigation. The responses of CO2 uptake by leaves to intercellular CO2 concentration and to absorbed light provide information for quantitative separation of the in vivo contribution of the different stages of photosynthesis to reduction in overall rate. This study uses these techniques to examine the basis of reduction in CO2 uptake in Zea mays cv. LG11 leaves following short‐term fumigation with SO2. Fumigation with 33 μmol m–3 SO2 for 30 min reduced light saturated CO2 uptake by about one‐third. An even greater reduction in light limited CO2 uptake was observed and with no significant change in light absorptance this was attributed to a reduced quantum yield of photosynthesis. The light saturated CO2 uptake rate and the stomatal conductance decreased in parallel. However, the relationship of CO2 uptake to the intercellular CO2 concentration suggested that the reduced stomatal conductance did not account for the reduced rate of CO2 uptake following fumigation. Both the initial slope and plateau of this relationship were significantly reduced, suggesting that both carboxylation efficiency and capacity for regeneration of CO2 acceptor were diminished by SO2 fumigation. The operating intercellular CO2 concentration indicated that both processes were co‐limiting, before and after fumigation. The time required for induction of photosynthetic CO2 uptake on illumination was approximately doubled following SO2 fumigation, showing that fumigation impairs the ability of the photosynthetic apparatus to adapt to fluctuations in light level.

Original languageEnglish (US)
Pages (from-to)193-200
Number of pages8
JournalPhysiologia Plantarum
Volume76
Issue number2
DOIs
StatePublished - Jun 1989
Externally publishedYes

Keywords

  • Atmospheric pollution
  • C4 photosynthesis
  • CO uptake
  • SO
  • Zea mays
  • leaf gas‐exchange
  • mesophyll
  • quantum yield
  • stomata

ASJC Scopus subject areas

  • Physiology
  • Genetics
  • Plant Science
  • Cell Biology

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