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Elevated CO2 Combats Water Stress in an Herb of the Mint Family

Paper Reviewed
Lee, S.H., Woo, S.Y. and Je, S.M. 2015. Effects of elevated CO2 and water stress on physiological responses of Perilla frutescens var. japonica HARA. Journal of Plant Growth Regulation 75: 427-434.

Lee et al. (2015) grew Perilla frutescens var. japonica 'Arum' -- an herb of the mint family that possesses both culinary and industrial uses -- from seeds that they planted in plastic pots containing a 1:1 peat:perlite mixture for a period of 60 days in two controlled-environment chambers, where they say that "the pots were flushed once a day and fertilized twice a week with a nutrient solution developed for leafy vegetables," and where -- after the first week of these treatments -- the plants were exposed to either near-ambient or elevated atmospheric CO2 concentrations (350 vs. 680 ppm, respectively) for the remainder of the experiment.

In this study, the three Korean researchers determined that, relative to the plants growing in near-ambient CO2 air, for the plants growing in the CO2 enriched air: (1) "photosynthetic rate was higher," (2) "stomatal resistance increased," (3) "transpiration rates declined," (4) "water-use efficiency rose," and, as a result, that (5) the elevated CO2 concentration reduced drought-induced oxidative damage to the plants.

Effect of elevated CO2 on photosynthetic rate, stomatal resistance, and transpiration in P. frutescens after five days of treatment under both well-watered and drought-stressed conditions.

And so it was that they additionally concluded in the final sentence of their paper that (6) "this effect of elevated CO2 levels on anti-oxidative defense systems should be considered as an important factor in the present environment," as well as, we might add, in any environment of the future in which plant stressors such as drought might periodically threaten P. frutescens' productivity.

Posted 16 June 2015