Net CO2 assimilation of cacao seedlings following dark chilling
1991
Joly, R.J. | Hahn, D.T.
Overnight exposure of cacao (Theobroma cacao L.) seedlings to chilling temperatures between 4.7 and 15.8 degrees C reduced net CO2 assimilation rate (A) and stomatal conductance to water vapor (g(s)), with temperatures below 10 degrees C causing severe inhibition. Net CO2 assimilation rates of chilled seedlings recovered to those of nonchilled plants within 7 days. No differences in daytime intercellular CO2 concentration (c(i)) with overnight temperature were observed on the first day after the chilling treatment, which indicates that the reduction in photosynthesis was not caused by the reduction in stomatal conductance. However, c(i) of chilled plants was much less than that of nonchilled plants on the second day after treatment, which suggests that chilling caused a change in stomatal response to CO2 concentration. Even 7 days after treatment, when A had recovered to control values, g(s) of chilled leaves was only approximately 70% that of controls. Chilling did not inhibit A through an effect on leaf water potential, which was higher in chilled plants than in unchilled plants.
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