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

Abstract

Climate change and future warming will significantly affect crop yield. The capacity of crops to dynamically adjust physiological processes (i.e., acclimate) to warming might improve overall performance. Understanding and quantifying the degree of acclimation in field crops could ensure better parameterization of crop and Earth System models and predictions of crop performance. We hypothesized that for field‐grown wheat, when measured at a common temperature (25°C), crops grown under warmer conditions would exhibit acclimation, leading to enhanced crop performance and yield. Acclimation was defined as (a) decreased rates of net photosynthesis at 25°C (A25) coupled with lower maximum carboxylation capacity (Vcmax25), (b) reduced leaf dark respiration at 25°C (both in terms of O2 consumption Rdark_O225 and CO2 efflux Rdark_CO225) and (c) lower Rdark_CO225 to Vcmax25 ratio. Field experiments were conducted over two seasons with 20 wheat genotypes, sown at three different planting dates, to test these hypotheses. Leaf‐level CO2‐based traits (A25, Rdark_CO225 and Vcmax25) did not show the classic acclimation responses that we hypothesized; by contrast, the hypothesized changes in Rdark_O2 were observed. These findings have implications for predictive crop models that assume similar temperature response among these physiological processes and for predictions of crop performance in a future warmer world.

The potential of resilient carbon dynamics for stabilizing crop reproductive development and productivity during heat stress

“…Plants acclimate respiration according to the demand for respiratory substrates as determined by the prevailing temperature (Coast et al, 2020; Dusenge et al, 2019; O'Leary et al, 2017). Genotypes from warm environments demonstrate reduced respiration than those from colder environments when grown at commonly high temperatures (Atkin & Tjoelker, 2003).…”

Photosynthetic heat tolerance in wheat: Evidence for genotype-by-environment interactions

“…The field trials were primarily rainfed, with supplemental watering provided by an overhead centre pivot (Dingwall) or overhead lateral move (Barraport West and Narrabri) irrigator. While the total amount of water supplied at Dingwall was lower than Barraport West, both sites received adequate irrigation, and yield of the Dingwall trial was consistently higher than Barraport West (Coast et al, 2021).…”

“…For greater impact, T crit GEI should be considered alongside other relevant energy-related physiological traits. For example, our recent works showed stronger response of wheat mitochondrial respiration in the dark (O 2 consumption basis, R dark O 2 ) to high temperature stress than photosynthesis, and greaterR dark O 2 response to night than day warming (Coast et al, 2021;Posch et al, 2021). Under warm nights wheat biomass fell in association with decline inR dark O 2 and increased alternative oxidase pathway capacity, suggesting a reduction in plant energy demand under warm nights.…”

Scaling plant responses to high temperature from cell to ecosystem

“…Scafaro et al (2021) synthesize current knowledge on how mitochondrial respiration responds to heat, including changes to respiratory metabolism under moderate heat and the inactivation of respiratory enzymes under excessive temperatures. This push‐pull mechanism is further examined by Coast et al (2021), who evaluated the acclimation of both photosynthesis and respiration to higher growth temperatures in wheat and found temperature‐dependent shifts in source‐sink dynamics. Continuing the theme of carbon balance, Ferguson, Tidy, Murchie, and Wilson (2021) highlight the need to sustain carbon supply to ensure the viability of reproductive organs for maintaining productivity under heat stress.…”