Appropriate Bandwidth Achieved High Yield Via Shrinking Maize Intraspecific Competition in an Additive Maize-Soybean Strip Intercropping

Maize-soybean strip intercropping has the advantages of alleviating the contradiction of arable land in China, improving the utilization rate of resources, high yield and sustainability. The key to exert these advantages is to stabilize the maize yield. However, interspecific interactions (improvement of root nutrient availability) was the primary focus of studies on maize-soybean strip intercropping. Suitable narrow row spacing could maximize the benefit of maize-soybean strip intercropping, and fixed narrow row spacing, bandwidth increase can achieve high yield and mechanization of soybean. In practice, in order to ensure maize yield in intercropping, plant spacing decreased and intraspecific competition intensified as bandwidth increased. On this basis, it is particularly urgent to identify the status of intraspecific competition and the regulation effect on maize yield under the optimal narrow row spacing (40 cm) and the spacing between maize and soybean (60 cm). Field experiments was conducted from 2017 to 2020 to analyze intraspecific competition intensity of maize and the main limiting factors of yield exertion under different bandwidths. The results revealed that intraspecific competition rather than interspecific interactions contributed the most to maize yield in intercropping. Maize adapted to intraspecific competition by fine-tuning the ear-leaf angle, stem diameter and leaf area. With the increase of bandwidth, maize biomass at mature stage decreased by 8.03, 20.45, 28.67% and yield lost by 6.40, 19.37, 44.09% respectively, but the biomass proportion to ear here was no significant difference. Moreover, although the appropriate competition facilitated the transport of photosynthetic products to the maize root, allowing the root to flourish at 2.4 m, it was difficult to offset the loss of shoot photosynthetic biomass in maize intercropping. We concluded that the aboveground part contributed more to the intercropping than the underground part. 2 m were better bandwidth to ensure maize yield via reducing the maize intraspecific competition by fine-tuning canopy morphology while the shriveling canopy at 2.4 m and 2.8 m limited the extensive promotion of the maize-soybean intercropping system