Stomatal conductance reduction tradeoffs in maize leaves: A theoretical study

Area of Science:

• Agricultural science
• Plant physiology
• Crop modeling

Background:

• Maize is a vital global grain crop heavily influencing agricultural water consumption.
• Modern maize photosynthesis is saturated with CO2, suggesting reduced stomatal conductance could save water without harming photosynthesis.

Purpose of the Study:

• To investigate the impact of reduced stomatal conductance on water use efficiency (WUE) in maize leaves across diverse microenvironments.
• To explore potential tradeoffs associated with reduced stomatal conductance, such as increased leaf temperature and its effect on WUE.
• To assess the resilience of these WUE benefits under projected climate change scenarios.

Main Methods:

• Utilized a process-based leaf model to simulate maize leaf responses.
• Analyzed the effects of reduced stomatal conductance under varying microenvironmental conditions (light, nitrogen availability).
• Quantified changes in photosynthesis, transpiration, leaf temperature, and water use efficiency.

Main Results:

• Reduced stomatal conductance can diminish WUE gains by up to 20% due to increased leaf temperature.
• A 29% reduction in stomatal conductance in upper canopy leaves yielded a 28% WUE gain without compromising photosynthesis.
• Lower canopy leaves showed superior WUE gains of 178% with reduced stomatal conductance, maintaining photosynthetic rates.

Conclusions:

• Reducing stomatal conductance in maize offers significant water use efficiency benefits, particularly in lower canopy leaves.
• The strategy provides substantial WUE gains without negatively impacting photosynthesis, even under non-optimal conditions.
• Simulated WUE improvements are robust and resilient to the impacts of climate change.