Plasticity in stomatal behavior across a gradient of water supply is consistent among field-grown maize inbred lines with varying stomatal patterning

Abstract

Stomata regulate leaf CO2 assimilation (A) and water loss. The Ball–Berry and Medlyn models predict stomatal conductance (gs) with a slope parameter (m or g1) that reflects sensitivity of gs to A, atmospheric CO2 and humidity, and is inversely related to water use efficiency (WUE). This study addressed knowledge gaps about what the values of m and g1 are in C4 crops under field conditions, as well as how they vary among genotypes and with drought stress. m and g1 were unexpectedly consistent in four inbred maize genotypes across a gradient of water supply. This was despite genotypic variation in stomatal patterning, A and gs. m and g1 were strongly correlated with soil water content, moderately correlated with pre-dawn leaf water potential (Ψpd), and weakly correlated with midday leaf water potential (Ψmd). This implied that m and g1 respond to long-term water supply more than short-term drought stress. The conserved nature of m and g1 across anatomically diverse genotypes and water supplies suggests there is flexibility in structure-function relationships underpinning WUE. This evidence can guide simulation of maize gs across a range of water supply in the primary maize growing region and inform efforts to improve WUE.Summary statementParameter values for models simulating stomatal conductance were unexpectedly consistent for anatomically and physiologically diverse genotypes of the model C4 crop maize when they were grown across a range of water supplies in the field.

Physiological trait networks enhance understanding of crop growth and water use in contrasting environments

“…However, two important caveats need to to be considered. Firstly, roots, stomata, and photochemistry are known to be significantly plastic in field grown maize (Ding et al, 2022; Gleason et al, 2017b; Schneider et al, 2020)⁠⁠. Although we do not address trait plasticity here, we should almost certainly expect attenuation of adverse intrinsic trait effects via a coordinated plastic response.…”

Physiological trait networks enhance understanding of crop growth and water use in contrasting environments

“…As such, superior genotypes tailored for the wet scenario would be ill-designed for dry scenarios (and vice versa), and especially dry scenarios where late season growth requires stored soil water . However, roots, stomata, and photochemistry are known to be significantly plastic in field grown maize (Gleason et al 2017b; Schneider et al 2020; Ding et al 2021). Although we do not address trait plasticity here, we should almost certainly expect attenuation of adverse intrinsic trait effects via a coordinated plastic response.…”