Light Distribution, Interception and Use Efficiency of Drip-Fertigated Maize-Soybean Strip Intercropping Systems...

Intercropping greatly affects canopy structure compared to monocropping, which in turn leads to changes in light distribution and subsequently crop yields. However, the light distribution, interception and use efficiency of maize-soybean strip intercropping systems with various row configurations, and especially the relationships between border row proportion or band width proportion and light utilisation and grain yield are still poorly understood. A two-season (2022 and 2023) field experiment was performed on maize and soybean under drip fertigation in the arid northwest China, with eight intercropping patterns and two controls of monocropping maize and soybean. Plant growth, grain yield and canopy photosynthetically active radiation were measured, and light interception fraction was simulated using a strip crop structure model. The results showed that intercropping reduced cumulative light interception of maize and soybean by 11.2% and 81.0% on average, respectively. The cumulative light interception of intercropping system was 13.0% smaller than that of monocropping soybean, but 13.7% greater than that of monocropping maize. Intercropping decreased light use efficiency of maize by 10.2%, but increased light use efficiency of soybean by 138.8% compared to monocropping. The spatial light distribution in intercropping varied greatly in the morning, midday, and afternoon compared to that of monocropping, especially for soybean. The band width proportion was significantly correlated with cumulative light interception of both maize and soybean as well as light use efficiency and grain yield of soybean. The border row proportion was significantly correlated with aboveground biomass and grain yield of both maize and soybean as well as light use efficiency of maize. When the border row proportion of maize was high and border row proportion of soybean was moderate (i.e., two rows of maize alternating with four rows of soybean), the grain yield of intercropping system was maximised. This study provides important information for improving intercropping models and optimising light distribution in maize-soybean strip intercropping systems.