What question did this study set out to answer?

The study aims to investigate how intercropped maize can maintain yield under limited water supply by integrating photosynthetic performance with C4 enzyme regulation.

April 28, 2026Open Access

Coupling photosynthetic physiology and C4 enzyme regulation enhances grain yield in no-tillage intercropped maize in an irrigated oasis region

Key Points

The study aims to investigate how intercropped maize can maintain yield under limited water supply by integrating photosynthetic performance with C4 enzyme regulation.
Field experiment conducted from 2022 to 2024
Evaluated no-tillage and conventional tillage, intercropping and monocropping patterns, and three irrigation levels
Measured grain yields, photosynthetic physiology, and enzyme regulation
CT×IM×I2 and NT×SM×I2 groups had significant yield increases of 10.5% and 27.2%, respectively, compared to NT×IM×I2
During silking to grain filling, treatments maintained higher relative chlorophyll, net photosynthesis, and stomatal conductance
Enzyme activities increased by 6-14%, with corresponding gene expression upregulated by 30-80%.

Abstract

Introduction The Hexi Oasis irrigation area is endowed with abundant light and heat resources, making it suitable for intercropped maize systems. However, increasing water scarcity and the need for irrigation reduction have made the conventional full-irrigation, high-yield pathway difficult to sustain. Under reduced irrigation, yield penalties may occur because water limitation directly constrains stomatal opening and carbon assimilation during the critical silking–grain filling period. Whether intercropped maize can stabilize yield under limited water supply through coordinated maintenance of photosynthetic performance and regulation of key C 4 enzymes remains unclear. Methods To address this gap, a field experiment was conducted in 2022–2024 to systematically evaluate the coupled effects of tillage (no-tillage, NT; conventional tillage, CT), cropping pattern (intercropping, IM; monocropping, SM), and three irrigation regimes (low, I1; medium, I2; high, I3) on maize grain yield, photosynthetic physiology, and key enzyme regulation. Results The results showed that compared with the NT×IM×I2 group, the grain yields of the CT×IM×I2 and NT×SM×I2 groups increased significantly by 10.5% and 27.2% respectively. During the silking–grain filling stage, this treatment maintained the highest relative chlorophyll content, net photosynthetic rate, stomatal conductance and effective quantum yield of PSII photochemistry, along with the lowest intercellular CO 2 concentration and quantum yield of non-regulated energy dissipation. Enzyme activities of phosphoenolpyruvate carboxylase, ribulose-1,5-bisphosphate carboxylase/oxygenase, and pyruvate phosphate dikinase increased by 6–11%, 8–10%, and 9–14%, respectively, with corresponding gene expression upregulated by 30–80%. Conclusion In summary, NT combined with moderate irrigation enhanced intercropped maize yield stability under limited water supply through a dual mechanism of “photosynthetic performance maintenance + C 4 enzyme activity/transcription enhancement.”

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