Row configuration affects plant growth and grain yield of drip-irrigated maize-soybean strip intercropping system by regulating photosynthetic capacity and grain filling process

Intercropping can establish multi-level, multi-crop, and multi-functional composite communities, making full use of limited resources. Reasonable row configuration helps reduce individual competition and improve resources utilization. However, the responses of photosynthetic capacity and grain filling process of intercropping maize and soybean to various row configurations under film-mulched drip fertigation remain poorly understood. A two-year field experiment (2022 and 2023) was conducted on drip-irrigated maize and soybean in the Hexi Region of China with eight maize-soybean intercropping patterns and two monocropping maize/soybean controls, so as to explore the photosynthesis, fluorescence, chlorophyll formation, dry matter accumulation, nitrogen uptake, grain filling, grain water content, and grain yield of maize-soybean intercropping systems. The results showed that intercropping reduced net photosynthetic rate, stomatal conductance, transpiration rate, effective quantum yield of PSII photochemistry of maize and soybean, resulting in reduced dry matter, grain filling rate, 100-grain weight and ultimately reduced grain yield (by 13.08 % for maize and 48.73 % for soybean compared to monocropping). Among the row configurations, two rows of maize with four rows of soybean (M2S4) achieved the maximum population yield, where the net photosynthetic rate of maize and soybean in M2S4 was highest, 12.44 % and 18.14 % lower than that of monocropping maize and soybean, respectively. In addition, the PSII photochemically effective quantum yield, dry matter, grain filling ratio, 100-grain weight, and nitrogen uptake of maize in M2S4 were second only to those of two rows of maize with two rows of soybean. In conclusion, the M2S4 maize-soybean strip intercropping system can maximize resources utilization and obtain the maximum benefit of maize under film-mulched drip fertigation in the Hexi Region of China. This study deepens our understanding of how row configuration affect crop yields from physiological perspectives, and provides new ideas and methods for optimizing row configuration to increase population yield of drip-irrigated maize-soybean strip intercropping systems. • Row configuration significantly affected leaf physiological characteristics and grain filling parameters. • Leaf photosynthetic capacity of intercropped maize and soybean was significantly reduced. • Intercropping reduced the grain filling rate and dehydration rate in both maize and soybean. • Intercropping significantly reduced N uptake in maize and soybean and increased maize N use efficiency. • Intercropping increased maize harvest index, but decreased soybean harvest index.