Qingfeng Song1, Venkatraman Srinivasan2, Steve P Long2,3, Xin-Guang Zhu1. 1. National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China. 2. Departments of Crop Sciences and of Plant Biology, Carl R. Woese Institute of Genomic Biology, University of Illinois at Urbana-Champaign, Urbana IL, USA. 3. Lancaster Environment Center, Lancaster University, Lancaster, UK.
Abstract
BACKGROUND AND AIMS: Understanding how climate change influences crop productivity helps identifying new options to increase crop productivity. Soybean is the most important dicotyledonous seed crop in terms of planting area. Though the impacts of elevated atmospheric [CO2] on soybean physiology, growth, and biomass accumulation have been studied extensively, the contribution of different factors to changes in season-long whole crop photosynthetic CO2 uptake (gross primary productivity - GPP) under elevated [CO2] have not been fully quantified. METHODS: A 3D canopy model combining canopy 3D architecture, ray tracing and leaf photosynthesis model was built to: a) study the impacts of elevated [CO2] on soybean GPP across a whole growing season; b) dissect the contribution of different factors to changes in GPP; and c) determine the extent, if any, of synergism between [CO2] and light on changes in GPP. The model was parameterized from measurements of leaf physiology and canopy architectural parameters at the soybean Free Air CO2 Enrichment (SoyFACE) facility in Champaign, Illinois. KEY RESULTS: Using this model, we showed that both CO2 fertilization effect and changes in canopy architecture contributed to the large increase in GPP while acclimation in photosynthetic physiological parameters to elevated [CO2] and altered leaf temperature played only a minor role in the changes in GPP. Furthermore, at early developmental stages, elevated CO2 increased leaf area index (LAI) which led to increased canopy light absorption and canopy photosynthesis. At later developmental stages, on days with high ambient light levels, the proportion of leaves in a canopy limited by Rubisco carboxylation increased from 12.2% to 35.6%, which led to a greater enhancement of elevated [CO2] to GPP. CONCLUSIONS: This study develops a new method to dissect comtribution of different factors to responses of crops under climate change. We showed that there is a synergestic effect of CO2 and light on crop growth under elevated CO2 conditions.
BACKGROUND AND AIMS: Understanding how climate change influences crop productivity helps identifying new options to increase crop productivity. Soybean is the most important dicotyledonous seed crop in terms of planting area. Though the impacts of elevated atmospheric [CO2] on soybean physiology, growth, and biomass accumulation have been studied extensively, the contribution of different factors to changes in season-long whole crop photosynthetic CO2 uptake (gross primary productivity - GPP) under elevated [CO2] have not been fully quantified. METHODS: A 3D canopy model combining canopy 3D architecture, ray tracing and leaf photosynthesis model was built to: a) study the impacts of elevated [CO2] on soybean GPP across a whole growing season; b) dissect the contribution of different factors to changes in GPP; and c) determine the extent, if any, of synergism between [CO2] and light on changes in GPP. The model was parameterized from measurements of leaf physiology and canopy architectural parameters at the soybean Free Air CO2 Enrichment (SoyFACE) facility in Champaign, Illinois. KEY RESULTS: Using this model, we showed that both CO2 fertilization effect and changes in canopy architecture contributed to the large increase in GPP while acclimation in photosynthetic physiological parameters to elevated [CO2] and altered leaf temperature played only a minor role in the changes in GPP. Furthermore, at early developmental stages, elevated CO2 increased leaf area index (LAI) which led to increased canopy light absorption and canopy photosynthesis. At later developmental stages, on days with high ambient light levels, the proportion of leaves in a canopy limited by Rubisco carboxylation increased from 12.2% to 35.6%, which led to a greater enhancement of elevated [CO2] to GPP. CONCLUSIONS: This study develops a new method to dissect comtribution of different factors to responses of crops under climate change. We showed that there is a synergestic effect of CO2 and light on crop growth under elevated CO2 conditions.