Water use efficiency control for a maize field under mulched drip irrigation

Area of Science:

• Agricultural Science
• Ecology
• Climate Science

Background:

• Water use efficiency (WUE) is crucial for understanding carbon-water coupling in agricultural ecosystems.
• Mechanisms controlling WUE in managed fields, particularly under mulched drip irrigation, require further elucidation.

Purpose of the Study:

• To investigate the environmental and biological factors regulating WUE in a maize field under mulched drip irrigation over an 8-year period.
• To quantify the effects of various factors on WUE across different timescales, growth stages, and hydrothermal conditions.

Main Methods:

• Utilized 8-year continuous observational data from a maize field in Northwestern China.
• Employed structural equation modeling, relative importance analysis, and principal component analysis.
• Quantified regulation effects of environmental (air temperature, vapor pressure deficit, net radiation) and biological (leaf biomass, root biomass) factors.

Main Results:

• Annual WUE ranged from 2.18 to 3.60 g C Kg⁻¹ H₂O (mean 2.91 g C Kg⁻¹ H₂O).
• Air temperature had the largest total effect on daily WUE across most conditions (0.61–0.91).
• Leaf biomass was the primary regulator of daily and interannual WUE (up to 75% importance in the vegetative stage).

Conclusions:

• Leaf biomass and air temperature are critical drivers of WUE in mulched drip-irrigated maize systems.
• Findings suggest that elevated air temperatures may enhance WUE under future climate warming scenarios.
• Improved understanding of carbon-water coupling provides insights for adapting crop ecosystems to climate change.