Diurnal and Seasonal Variations of Photosynthetic Energy Conversion Efficiency of Field Grown Wheat.

Qingfeng Song,Xin-Guang Zhu,Zhonghu He,Tiangen Chang,Jeroen Van Rie,Alexander Galle,Honglong Zhao,Bart Den Boer

doi:10.3389/fpls.2022.817654

Abstract

Improving canopy photosynthetic light use efficiency and energy conversion efficiency (εc) is a major option to increase crop yield potential. However, so far, the diurnal and seasonal variations of canopy light use efficiency (LUE) and εc are largely unknown due to the lack of an efficient method to estimate εc in a high temporal resolution. Here we quantified the dynamic changes of crop canopy LUE and εc during a day and a growing season with the canopy gas exchange method. A response curve of whole-plant carbon dioxide (CO2) flux to incident photosynthetically active radiation (PAR) was further used to calculate εc and LUE at a high temporal resolution. Results show that the LUE of two wheat cultivars with different canopy architectures at five stages varies between 0.01 to about 0.05 mol CO2 mol–1 photon, with the LUE being higher under medium PAR. Throughout the growing season, the εc varies from 0.5 to 3.7% (11–80% of the maximal εc for C3 plants) with incident PAR identified as a major factor controlling variation of εc. The estimated average εc from tillering to grain filling stages was about 2.17%, i.e., 47.2% of the theoretical maximal. The estimated season-averaged radiation use efficiency (RUE) was 1.5–1.7 g MJ–1, which was similar to the estimated RUE based on biomass harvesting. The large variations of LUE and εc imply a great opportunity to improve canopy photosynthesis for greater wheat biomass and yield potential.

Highlights

Crop radiation use efficiency is the efficiency with which a crop utilizes absorbed light energy for biomass production and is calculated as the ratio of biomass accumulation per unit of absorbed or intercepted photosynthetically active radiation (PAR) (Monteith and Moss, 1977; Sinclair and Muchow, 1999; Hatfield, 2014)
This article shows that in the field there are large diurnal and seasonal variations of canopy light use efficiency (LUE), radiation use efficiency (RUE), and εc estimated with chamber-based canopy photosynthesis measurements and recordings of diurnal changes of photosynthetic active radiation
This light-dependent LUE variation is consistent with the result of meta-analysis which shows that the energy conversion efficiency is higher under shading treatment (Slattery et al, 2013)

Summary

Introduction

Crop radiation use efficiency is the efficiency with which a crop utilizes absorbed light energy for biomass production and is calculated as the ratio of biomass accumulation per unit of absorbed or intercepted photosynthetically active radiation (PAR) (Monteith and Moss, 1977; Sinclair and Muchow, 1999; Hatfield, 2014). Increasing radiation use efficiency (RUE) is an important option. Variations of Energy Conversion Efficiency to increase crop biomass production and yield potential (Reynolds et al, 2000; Zhu et al, 2010). Canopy photosynthesis is influenced by both the canopy architecture (Song et al, 2013; Burgess et al, 2017) and leaf photosynthetic capacities at different layers of the canopy (Murchie et al, 2002). Differences in canopy architecture can influence canopy microclimate, especially the light environments inside a canopy (Burgess et al, 2017). Many studies show a strong influence of sink-related activities on biomass production and RUE (see review in Chang et al, 2017)

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