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Effects on long-term enhanced CO-2 partial pressure on gas exchange parameters and saccharide pools of wheat leaves

D.M.thes, M.A.G.einer; Knoppik, D.

Photosynthetica (Prague) 30(3): 435-445

1994


ISSN/ISBN: 0300-3604
Accession: 008586858

Wheat plants were cultivated in a growth chamber at normal (35 Pa, c-35 plants) and enhanced (70 Pa, c-70 plants) CO-2 partial pressure. In c-35 plants the net photosynthetic rate (P-N) of flag leaves and the concentrations of saccharides such as sucrose, glucose, fructose and starch were increased. The c-70 plants possessed higher chlorophyll (Chl) a and Chl b contents. The CO-2 response of P-N at saturating photosynthetically active radiation (PAR) was very similar for both variants. At the highest CO-2 concentration saccharides accumulated in both variants as a consequence of decreased export rate. The response of P-N to PAR at saturating CO-2 concentrations was similar in the two variants. On the other hand, the response of water vapor pressure conductance (g-H-2-0) to PAR in c-35 plants followed a hyperbolic response to PAR, while in the c-70 plants it was linearly related to PAR up to the mean PAR used for growth. In this variant g-H-2-0 seemed to change parallelly to changes in the mesophyll demand for CO-2 caused by PAR.

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