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The Impact of Elevated CO2 and Temperature on Chinese Yam

Paper Reviewed
Thinh, N.C., Kumagai, E., Shimono, H. and Kawasaki, M. 2017. Effects of elevated CO2 concentration on bubil germination and early seedling growth in Chinese yam under different air temperatures. Plant Production Science 20: 313-322.

Writing as background for their study, Thinh et al. (2017) say that "under future climate change scenarios, it is likely that plants will be exposed to a combination of both higher CO2 and air temperature." Therefore, they note it is important for studies to be conducted investigating both the singular and interactive effects of these phenomena.

As their contribution to the subject, the four Japanese researchers set out to examine "the effects of elevated CO2 and air temperature on the germination of seed bulbils and the seedling vigor of two Chinese yam lines." Their experiment was conducted in controlled-environment chambers in a naturally sunlit greenhouse at the Tohoku Agricultural Research Center in Morioka, Japan. The two yam lines included Enshikel 6 and Shojikei, both of which are widely cultivated in northern Japan. The elevated CO2 levels examined included ambient (406 ppm) and elevated (603 ppm) and the two temperature treatments were 22.2 and 25.6 °C, representing ambient and high temperatures, respectively. The length of the experiment was 35 days. So how did the plants fare under such conditions?

Bulbil germination was unaffected by CO2 and/or temperature levels, with percentages reaching approximately 100 percent in all treatments. Elevated CO2, however, did positively impact a number of growth-related parameters in both yam lines, including leaf number, leaf area and shoot and root length, as well as the dry weight of the leaves, vines, shoots, roots and tubers, leading to whole-plant dry weight increases of 21 and 29 percent for Enshikel 6 and 33 and 25 percent for Shojikei under ambient and high temperatures, respectively. Additionally, elevated CO2 stimulated the seedling vigor of both plants by 14 to 32 percent. Temperature, in contrast, had little impact - either alone or in combination with CO2 - on yam growth. Consequently, in light of their many findings listed above, Thinh et al. conclude that "Chinese yam seedlings respond positively to elevated CO2," and that conclusion should excite those who grow and consume this important crop.

Posted 3 October 2017