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Effects of Elevated CO2 on the Growth and Physiology of Peach Seedlings
Centritto, M.  2002.  The effects of elevated [CO2] and water availability on growth and physiology of peach (Prunus persica) plants.  Plant Biosystems 136: 177-188..

What was done
Peach seedlings were maintained for two growing seasons in pots in open-top chambers of either ambient or CO2-enriched air (350 or 700 ppm, respectively) inside a glasshouse.  All plants were continuously maintained at optimum soil fertility and, for the entire first growing season, at optimum soil water availability.  In the second growing season, however, half of the seedlings had water withheld from them for a period of four weeks.

What was learned
At the end of the study, there were no CO2-induced differences in the basal diameters of the seedlings.  In terms of total dry weight, however, the elevated CO2 enhanced the growth of the water-stressed seedlings by 30% and the growth of the well-watered seedlings by 35%, which was largely a consequence of increased height growth.

There was no evidence of any downward acclimation of photosynthesis in the seedlings grown at elevated CO2.  Neither was there any downward acclimation in Rubisco carboxylation efficiency nor in the maximum RuBP regeneration capacity mediated by electron transport.

There were also no significant effects of elevated CO2 on stomatal conductance in either of the two water treatments.  Because of the CO2-induced increase in plant growth, however, there was a complementary increase in seedling water use efficiency, even though there was no difference in total water uptake between the two CO2 treatments.

What it means
Based on these findings, it would appear that in a world of the future where atmospheric CO2 concentration is approximately doubled, young peach trees will likely produce about a third more growth on the same amount of water as they do today.

Reviewed 18 June 2003