Stomatal conductance reduction tradeoffs in maize leaves: A theoretical study.

Abstract

As the leading global grain crop, maize significantly impacts agricultural water usage. Presently, photosynthesis ( ) in leaves of modern maize crops is saturated with , implying that reducing stomatal conductance ( ) would not affect but reduce transpiration ( ), thereby increasing water use efficiency (WUE). While reduction benefits upper canopy leaves under optimal conditions, the tradeoffs in low light and nitrogen-deficient leaves under nonoptimal microenvironments remain unexplored. Moreover, reduction increases leaf temperature ( ) and water vapor pressure deficit, partially counteracting transpiratory water savings. Therefore, the overall impact of reduction on water savings remains unclear. Here, we use a process-based leaf model to investigate the benefits of reduced in maize leaves under different microenvironments. Our findings show that increases in due to reduction can diminish WUE gains by up to 20%. However, reduction still results in beneficial WUE tradeoffs, where a 29% decrease in in upper canopy leaves results in a 28% WUE gain without loss in . Lower canopy leaves exhibit superior tradeoffs in reduction with 178% gains in WUE without loss in . Our simulations show that these WUE benefits are resilient to climate change.