Anatomical drivers of stomatal conductance in sorghum lines with different leaf widths grown under different temperatures

Abstract

SummaryImprovements in leaf water use efficiency (iWUE) can maintain crop productivity in water limited environments under rising temperatures. We investigated the leaf anatomical traits which underpin our recently identified link between leaf width (LW) andiWUE.Ten sorghum lines with varyingLWwere grown under three temperatures to expand the range of variation of bothLWand gas exchange rates. Leaf gas exchange, surface morphology and cross-sectional anatomy were measured and analysed using structural equations modelling.Narrower leaves had lower stomatal conductance (gs) and higheriWUEacross growth temperatures. They also had smaller intercellular airspaces, stomatal size, percentage of open stomatal aperture relative to maximum, hydraulic pathway, mesophyll thickness, and leaf mass per area. Structural modelling revealed a developmental association among leaf anatomical traits that underpinnedgsvariation in sorghum.Growing temperature andLWboth impacted leaf gas exchange rates, but onlyLWdirectly impacted leaf anatomy. Wider leaves may be more productive under well-watered conditions, but consume more water for growth and development, which is detrimental under water stress.HighlightCoordination between leaf width and leaf anatomy underpins stomatal conductance variation in sorghum grown under different temperatures.