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Pear Trees in a CO2-Enriched and Warmer World

Han, J.-H., Cho, J.G., Son, I.-C., Kim, S.H., Lee, I.-B., Choi, I.M. and Kim, D. 2012. Effects of elevated carbon dioxide and temperature on photosynthesis and fruit characteristics of 'Niitaka' pear (Pyrus pyrifolia Nakai). Horticulture, Environment and Biotechnology 53: 357-361.
How will their fruit of pear trees in a CO2-enriched and warmer world of the future likely compare with the fruit of today's trees? This was the question addressed in a recent study by Han et al. (2012). In rather pessimistic words, the seven scientists write as background for their work that, "in order to predict problems in the production of pear caused by climate change," three-year-old 'Niitaka' pears were cultivated in a rhizotron within compartments of controlled temperature [ambient and ambient + 4°C] and atmospheric CO2 concentration [ambient (390 ppm) and elevated (700 ppm)], plus all combinations thereof, at the National Institute of Horticultural & Herbal Science in Suwon, Korea, from April 20 to October 2, 2010.

In describing their findings, Han et al. report that:
   (1) pear leaf photosynthetic rates in July and August were high in plants under elevated CO2 concentration
   (2) pear color change from green to light yellow during the ripening period was enhanced in the elevated CO2 treatment
   (3) fruit weight at harvest was the highest in the elevated CO2 group
   (4) flesh firmness at harvest was the highest in the elevated temperature group
   (5) the soluble solids content of the fruit increased significantly in the group treated with high CO2.

The latter of these findings was said by Han et al. to be "consistent with the report of Islam et al. (1996) that enzymatic activity and soluble solids content increased in tomato treated with high CO2 concentration," and they additionally note that "Ito et al. (2002) found that elevated CO2 "improves not only the biomass of the plant but also fruit size and quality in pears."

Now if only all of the "problems caused by climate change" would be found to be like those of pears, what a wonderful world this would be!

Additional References
Islam, S., Matsui, T. and Yoshida, Y. 1996. Effect of carbon dioxide enrichment on physico-chemical and enzymatic changes in tomato fruits at various stages of maturity. Scientia Horticulturae 65: 137-149.

Ito, J., Hasegawa, S., Fujita, K., Ogasawara, S. and Fuiwara, T. 2002. Changes in water relations induced by CO2 enrichment govern diurnal stem and fruit diameters of Japanese pear. Plant Science 163: 1169-1176.

Archived 8 May 2013