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Impact of ambient [C02] on chlorophyll a fluorescence characteristics of the photosynthetic apparatus in tomato plants and its link with effects of soil flooding

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Janowiak F., M.A. E., Jackson M. B.

Zeszyty Problemowe Postępów Nauk Rolniczych

2004

tom 496

nr 1

We examined if raising ambient carbon dioxide (CO₂) concentrations sufficiently to trigger stomatal closure reproduces effects of soil flooding on chlorophyll a fluorescence parameters. Like soil flooding, raising [CO₂] from 360 to 560 µmol.mol⁻¹ closed stomata. It also reduced the quantum efficiency of PS II photochemistry (Fq'/Fm') and decreased the overall maximum photosynthetic efficiency of dark-adapted plants (Fv/Fm). Such changes in fluorescence parameters were similar to those that take place during soil flooding. We conclude that this concentration of external CO₂ mimics soil flooding by closing the stomata thereby depriving the photosynthetic apparatus of CO₂, which led, in turn, to changes in fluorescence parameters. When this CO₂ shortfall was overcome by raising external CO₂ concentrations to 960 µmol.mol⁻¹ fluorescence parameters were little changed, despite causing stomatal closure. Presumably, at this higher ambient concentration, C, was sufficient to avoid damage to the light reaction centres. We conclude that flooding-induced changes to photosynthetic efficiency, as assessed by chlorophyll a fluorescence, result mostly from limited CO₂ availability caused by stomatal closure.

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1 Zeszyty Problemowe Postępów Nauk Rolniczych

1 Jackson M. B.

1 Janowiak F.

1 M.A. E.

1 2004

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Impact of ambient [C02] on chlorophyll a fluorescence characteristics of the photosynthetic apparatus in tomato plants and its link with effects of soil flooding