The CO2 fertilization effect on leaf photosynthesis of maize (Zea mays L.) depends on growth temperatures with changes in leaf anatomy and soluble sugars

Liang Liu; Lihua Hao; Yunxin Zhang; Haoran Zhou; Baoguo Ma; Yao Cheng; Yinshuai Tian; Zhijie Chang; Yunpu Zheng

doi:10.3389/fpls.2022.890928

The CO₂ fertilization effect on leaf photosynthesis of maize (Zea mays L.) depends on growth temperatures with changes in leaf anatomy and soluble sugars

Front Plant Sci. 2022 Aug 19:13:890928. doi: 10.3389/fpls.2022.890928. eCollection 2022.

Authors

Liang Liu¹, Lihua Hao¹, Yunxin Zhang¹, Haoran Zhou², Baoguo Ma¹, Yao Cheng¹, Yinshuai Tian³, Zhijie Chang¹, Yunpu Zheng¹

Affiliations

¹ School of Water Conservancy and Hydropower, Hebei University of Engineering, Handan, China.
² Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States.
³ School of Landscape and Ecological Engineering, Hebei University of Engineering, Handan, China.

Abstract

Understanding the potential mechanisms and processes of leaf photosynthesis in response to elevated CO₂ concentration ([CO₂]) and temperature is critical for estimating the impacts of climatic change on the growth and yield in crops such as maize (Zea mays L.), which is a widely cultivated C₄ crop all over the world. We examined the combined effect of elevated [CO₂] and temperature on plant growth, leaf photosynthesis, stomatal traits, and biochemical compositions of maize with six environmental growth chambers controlling two CO₂ levels (400 and 800 μmol mol^-1) and three temperature regimes (25/19°C, 31/25°C, and 37/31°C). We found that leaf photosynthesis was significantly enhanced by increasing growth temperature from 25/19°C to 31/25°C independent of [CO₂]. However, leaf photosynthesis drastically declined when the growth temperature was continually increased to 37/31°C at both ambient CO₂ concentration (400 μmol mol^-1, a[CO₂]) and elevated CO₂ concentration (800 μmol mol^-1, e[CO₂]). Meanwhile, we also found strong CO₂ fertilization effect on maize plants grown at the highest temperature (37/31°C), as evidenced by the higher leaf photosynthesis at e[CO₂] than that at a[CO₂], although leaf photosynthesis was similar between a[CO₂] and e[CO₂] under the other two temperature regimes of 25/19°C and 31/25°C. Furthermore, we also found that e[CO₂] resulted in an increase in leaf soluble sugar, which was positively related with leaf photosynthesis under the high temperature regime of 37/31°C (R ² = 0.77). In addition, our results showed that e[CO₂] substantially decreased leaf transpiration rates of maize plants, which might be partially attributed to the reduced stomatal openness as demonstrated by the declined stomatal width and stomatal area. These results suggest that the CO₂ fertilization effect on plant growth and leaf photosynthesis of maize depends on growth temperatures through changing stomatal traits, leaf anatomy, and soluble sugar contents.

Keywords: leaf anatomy; photosynthesis; stomatal traits; total soluble sugar; water use efficiency.