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The Interactive Effects of Elevated CO2 and Arbuscular Mycorrhiza on Wheat Growth

Paper Reviewed
Zhu, X., Song, F., Liu, S. and Liu, F. 2016. Arbuscular mycorrhiza improve growth, nitrogen uptake, and nitrogen use efficiency in wheat grown under elevated CO2. Mycorrhiza 26: 133-140.

Wheat is one of the most important global food crops and many studies have documented the positive effects of atmospheric CO2 enrichment on this key agricultural species (see, for example, the nearly 300 individual experimental results posted for wheat in our Plant Growth Database). In addition to elevated CO2, wheat production has also been shown to benefit when arbuscular mycorrhizal fungi (AM), an important group of obligate biotrophic symbionts at the soil-root interface, are present, as AM have been shown to provide a crucial link for nutrient exchange between plants and soil. However, not much is known about the interactive effects of elevated CO2 and AM presence on wheat. Thus, it was the recent objective of Zhu et al. (2016) "to evaluate the effects of an AM fungus on biomass, C and N accumulation and partitioning, [and] N use efficiency of wheat plants grown in ambient and elevated CO2 concentrations."

In order to accomplish their design, the four scientists grew wheat (Triticum aestivum L.) in experimental pots within a climate-controlled glasshouse at the experimental farm of the Department of Plant and Environmental Sciences, University of Copenhagen, Taastrup, Denmark, under ambient (400 ppm) or elevated (700 ppm) CO2 concentrations and with or without AM (inoculated with Rhizophagus irregularis) for a period of 10 weeks. Thereafter, plant and soil samples were analyzed for a number of characteristics to determine the singular and interactive effects of these variables.

Results indicated, in the words of the authors, that elevated CO2 "stimulated R. irregularis root colonization and plant growth in wheat," which stimulation fostered an increase in the C concentration of the leaves, stems and roots that resulted in a 56 percent increase in total plant dry weight in AM wheat plants over non-AM plants. Zhu et al. also found that "AM symbiosis favors C and N partitioning in roots, increases C accumulation and N uptake, and leads to greater nitrogen use efficiency in wheat plants grown at elevated CO2." Thus it is that, in the future, AM symbiosis and elevated CO2 will act together to improve the growth and production of this most important global food crop.

Posted 21 July 2016