Optimizing water-nitrogen coupling for quinoa yield, quality, and resource use efficiency in arid regions

Area of Science:

• Agricultural Science
• Agronomy
• Soil Science

Background:

• Water and nitrogen are critical inputs for crop production.
• Drip irrigation offers efficient water delivery, but its interaction with nitrogen fertilization requires optimization.
• Quinoa is a nutrient-dense crop with growing global importance.

Purpose of the Study:

• To determine the optimal water-nitrogen management strategy for quinoa under drip irrigation in Xinjiang.
• To investigate the effects of varying irrigation and nitrogen levels on quinoa yield, grain quality, and resource use efficiency.
• To establish a yield response model and identify critical thresholds for nitrogen application.

Main Methods:

• A microplot experiment utilized a two-factor factorial design with three irrigation levels (2,100–3,300 m³/ha) and five nitrogen rates (0–175 kg/ha).
• Dry matter accumulation, yield, grain quality parameters (fat, protein, starch content), and water-nitrogen use efficiencies were measured.
• Statistical analyses and regression modeling were employed to analyze the data and predict optimal conditions.

Main Results:

• Increasing nitrogen enhanced dry matter under lower irrigation, but a threshold effect was observed under higher irrigation, with dry matter declining above 150 kg/ha.
• A yield response model predicted maximum yield at 2,931.59 m³/ha irrigation and 149.24 kg/ha nitrogen.
• Optimal grain quality was achieved with moderate irrigation (2,700–3,300 m³/ha) and nitrogen (125–150 kg/ha), while peak water use efficiency (WUE), nitrogen agronomic efficiency (NAE), and nitrogen partial factor productivity (NPFP) were identified.

Conclusions:

• A recommended water-nitrogen management strategy for quinoa in southern Xinjiang is 2,700 m³/ha drip irrigation combined with 150 kg/ha nitrogen fertilizer.
• This strategy balances high yield, superior grain quality, and efficient resource utilization.
• The findings contribute to sustainable agricultural practices in arid and semi-arid regions.