Light interception and use efficiency differ with maize plant density in maize-peanut intercropping

• Intercropping intercepted more light than sole peanut but less than sole maize. • Maize light use efficiency (LUE) increased with plant density in the intercropping. • Intercropping did not affect LUE of maize but increased peanut LUE. Intercropping increases crop yields by optimizing light interception and/or use efficiency. Although intercropping combinations and metrics have been reported, the effects of plant density on light use are not well documented. Here, we examined the light interception and use efficiency in maize-peanut intercropping with different maize plant densities in two row configurations in semiarid dryland agriculture over a two-year period. The field experiment comprised four cropping systems, i.e. monocropped maize, monocropped peanut, maize-peanut intercropping with two rows of maize and four rows of peanut, intercropping with four rows of maize and four rows of peanut, and three maize plant densities (3.0, 4.5 and 6.0 plants m−1 row) in both monocropped and intercropping maize. The mean total light interception in intercropping across years and densities was 779 MJ·m−2, 5.5% higher than in monocropped peanut (737 MJ·m−2) and 7.6% lower than in monocropped maize (843 MJ·m−2). Increasing maize density increased light interception in monocropped maize but did not affect the total light interception in the intercrops. Across years the LUE of maize was 2.9 g·MJ−1 and was not affected by cropping system but increased with maize plant density. The LUE of peanut was enhanced in intercropping, especially in a wetter year. The yield advantage of maize-peanut intercropping resulted mainly from the LUE of peanut. These results will help to optimize agronomic management and system design and provide evidence for system level light use efficiency in intercropping.