Effects of Elevated CO2 on Wheat Yield: Non-Linear Response and Relation to Site Productivity

Malin C Broberg,Håkan Pleijel,Petra Högy,Zhaozhong Feng

doi:10.3390/agronomy9050243

Abstract

Elevated carbon dioxide (eCO2) is well known to stimulate plant photosynthesis and growth. Elevated carbon dioxide’s effects on crop yields are of particular interest due to concerns for future food security. We compiled experimental data where field-grown wheat (Triticum aestivum Linnaeus) was exposed to different CO2 concentrations. Yield and yield components were analyzed by meta-analysis to estimate average effects, and response functions derived to assess effect size in relation to CO2 concentration. Grain yield increased by 26% under eCO2 (average ambient concentration of 372 ppm and elevated 605 ppm), mainly due to the increase in grain number. The response function for grain yield with CO2 concentration strongly suggests a non-linear response, where yield stimulation levels off at ~600 ppm. This was supported by the meta-analysis, which did not indicate any significant difference in yield stimulation in wheat grown at 456–600 ppm compared to 601–750 ppm. Yield response to eCO2 was independent of fumigation technique and rooting environment, but clearly related to site productivity, where relative CO2 yield stimulation was stronger in low productive systems. The non-linear yield response, saturating at a relatively modest elevation of CO2, was of large importance for crop modelling and assessments of future food production under rising CO2.

Highlights

Over the past four decades, multiple experiments have been performed to estimate the response of plants to higher concentrations of carbon dioxide (CO2 ) under field conditions
Grain yield significantly increased by 25.6% (CI 20.9–28.5%) under elevated CO2 (eCO2) and total aboveground biomass showed an equal response of 24.8% (CI 21.7–28.1%)
Grain number was significantly enhanced by 22.3% (CI 17.6–27.1%) due to eCO2, while grain mass showed a small, but still significant increase by 2.1% (CI 0.6–3.7%)

Summary

Introduction

Over the past four decades, multiple experiments have been performed to estimate the response of plants to higher concentrations of carbon dioxide (CO2 ) under field conditions. To explore the potential advantages of the fact that rising CO2 may stimulate plant growth. To assess possible yield stimulations, there is a need to estimate crop responses to elevated CO2 (eCO2 ). Wheat (Triticum aestivum Linnaeus) is one of the most studied crops regarding eCO2 responses, since it is one of the major food crops globally. Plant growth is generally stimulated by eCO2 , resulting in higher yields [3]. The growth stimulation is a result of both enhanced photosynthesis (C3 crops), and improved water use efficiency (C3 and C4 crops) due to reduced stomatal conductance [4].

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Results

Discussion

Conclusion