The acclimation of leaf photosynthesis of wheat and rice to seasonal temperature changes in T‐FACE environments

Abstract

Crops show considerable capacity to adjust their photosynthetic characteristics to seasonal changes in temperature. However, how photosynthesis acclimates to changes in seasonal temperature under future climate conditions has not been revealed. We measured leaf photosynthesis (An) of wheat (Triticum aestivum L.) and rice (Oryza sativa L.) grown under four combinations of two levels of CO2 (ambient and enriched up to 500 µmol/mol) and two levels of canopy temperature (ambient and increased by 1.5–2.0°C) in temperature by free‐air CO2 enrichment (T‐FACE) systems. Parameters of a biochemical C3‐photosynthesis model and of a stomatal conductance (gs) model were estimated for the four conditions and for several crop stages. Some biochemical parameters related to electron transport and most gs parameters showed acclimation to seasonal growth temperature in both crops. The acclimation response did not differ much between wheat and rice, nor among the four treatments of the T‐FACE systems, when the difference in the seasonal growth temperature was accounted for. The relationships between biochemical parameters and leaf nitrogen content were consistent across leaf ranks, developmental stages, and treatment conditions. The acclimation had a strong impact on gs model parameters: when parameter values of a particular stage were used, the model failed to correctly estimate gs values of other stages. Further analysis using the coupled gs–biochemical photosynthesis model showed that ignoring the acclimation effect did not result in critical errors in estimating leaf photosynthesis under future climate, as long as parameter values were measured or derived from data obtained before flowering.

Acclimation of leaf photosynthesis and respiration to warming in field‐grown wheat

“…In support of this finding, leaf CO 2 exchange also did not acclimate to night‐time warming in field‐grown wheat (Impa et al, 2019). By contrast, previous studies had reported lower rates of temperature‐normalized CO 2 exchange in warm versus cold acclimated plants across a range of species (Atkin & Tjoelker, 2003; Berry & Bjorkman, 1980; Way & Yamori, 2014); but, more widely, the leaf physiology responses of crop plants to elevated temperatures in field experiments have been inconsistent (Cai et al, 2018, 2020; Zheng et al, 2018; Zhou et al, 2018), suggesting that crops do not always exhibit classical thermal acclimation responses in the field. While the reason(s) for the disparity in acclimation responses of crop plants is unclear, it is likely that differences in the warming techniques, degree and duration of warming used in the field might be factors.…”

Alternative Crassulacean Acid Metabolism Modes Provide Environment-Specific Water-Saving Benefits in a Leaf Metabolic Model

“…The uptake rate for CO2 was limited to a value of 15 μmol m -2 s -1 based on values for different C3 and CAM species (Nobel, 2012). We assumed an average ci:c, ratio of 0.7 (Tan et al, 2017;Kumarathunge et al, 2019;Cai et al, 2020;Busch, 2020) (see Supplemental Methods, Section 1.2.5 and Supplemental Results, Section 2.5 for more information and a sensitivity analysis of the predicted water loss in dependence of the internal CO2 concentration). All other fluxes were unconstrained.…”

Wheat morpho‐physiological traits and radiation use efficiency under interactive effects of warming and tillage management

“…The interactive effects between warming and tillage on A max and SPAD were significant in the two years (Table 1), which might be ascribed to the increase of optimum temperature for photosynthesis under different tillage managements. This also suggests that photosynthetic characteristics of a crop could have an increased maximum capacity under future (Cai et al, 2020). In contrast to the normal season (2018/19), in the warmer season (2019/20), warming had negative effects on LW, k , A max , aboveground stems and spike biomass, RUE from anthesis to maturity, and consequently GY under CT.…”

“…The plant morphological plasticity could be affected by the interactions of genotype, environment and agronomic management (Bustos et al, 2013; Cartelle, Pedró, Savin, & Slafer, 2006; Hikosaka et al, 2016; Parry et al, 2011). Crops also have considerable capacity to adjust and acclimate their photosynthetic characteristics to changes in seasonal temperature under future climate conditions (Cai et al, 2016; Cai, Li, Di, Ding, & Yin, 2020). However, the changes in crop morphological and physiological traits, and their impacts on canopy light distribution and RUE, have rarely been investigated, especially under high temperature conditions and different tillage managements.…”