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Photosynthetic Recovery of Beans Following Chilling
Reference
Melkonian, J., Owens, T.G. and Wolfe, D.W.  2004.  Gas exchange and co-regulation of photochemical and nonphotochemical quenching in bean during chilling at ambient and elevated carbon dioxide.  Photosynthesis Research 79: 71-82.

What was done
Well-watered and fertilized mature bean plants (Phaseolus vulgaris L., cv. Bush Blue Lake 274) were grown in CO2-controlled growth chambers maintained at concentrations of either 350 or 700 ppm at 25/18°C day/night temperatures.  The plants then received 24 hours of chilling at 6.5°C (8 hours light, 10 hours dark, 6 hours light), after which there was a 24-hour recovery period under pre-chill growing conditions, followed by a second 24 hours of chilling, which was followed by a 48-hour recovery period consisting of pre-chill conditions.  Throughout this entire time, net photosynthesis measurements were made two to three hours before and after each shift in temperature.

What was learned
Prior to chilling, net photosynthesis was approximately 20% higher at elevated compared to ambient CO2.  During chilling, on the other hand, plants of both treatments exhibited near-identical much-reduced values.  Subsequently, however, and "consistent with previous research [Boese et al., 1997] on this cultivar," in the words of the authors, "post-chilling recovery was more rapid at elevated compared to ambient CO2."

What it means
Even though some stresses sometimes affect the physiological processes of plants grown in ambient and CO2-enriched air to approximately the same degree, the rate of recovery from the effects of those stresses is often accelerated in air enriched with CO2, as was the case here with photosynthesis after the easing of a debilitating drop in temperature.

Reference
Boese, S.R., Wolfe, D.W. and Melkonian, J.  1997.  Elevated CO2 mitigates chilling-induced water stress and photosynthetic reduction during chilling.  Plant, Cell and Environment 20: 624-632.


Reviewed 9 June 2004