Effective Water Use Required for Improving Crop Growth Rather Than Transpiration Efficiency

Area of Science:

• Agricultural Science
• Plant Physiology
• Crop Science

Background:

• Crop yield is linked to transpiration efficiency (TE).
• Previous research focused on improving the intrinsic leaf CO2/H2O exchange ratio for TE.
• This approach has shown limited success in increasing crop yields.

Purpose of the Study:

• To re-evaluate the mechanistic drivers of TE.
• To investigate the impact of daily vapor pressure deficit (VPD) on TE.
• To explore plant-driven water conservation strategies for yield enhancement.

Main Methods:

• Mechanistic derivation of TE based on Tanner and Sinclair's work.
• Analysis of the relationship between daily weighted VPD and TE.
• Review of experimental evidence and simulation studies on water use dynamics.

Main Results:

• Increasing the static, intrinsic TE ratio offers limited scope for improvement.
• Daily weighted VPD significantly impacts TE.
• Partial stomatal closure during midday reduces transpiration, conserving soil water.
• Conserved water supports late-season physiological activity and reproductive development.

Conclusions:

• Effective water use throughout the growing season is crucial for increasing crop yield.
• Plant-controlled water conservation strategies, rather than solely intrinsic TE improvements, are key.
• Shifting temporal water use dynamics can lead to substantial yield increases.