Mixed Cropping of Different Hybrids of Maize Optimizes Canopy Structure and Promotes Higher Grain Yield

Abstract

Under high‐density planting, mixed cropping planting pattern can potentially optimize maize (Zea mays L.) canopy architecture and ultimately improve grain yield. The objectives of this study were to evaluate the effects of three plant patterns combined with three plant population densities (67,500, 82,500, and 97,500 plants·ha−1) on canopy architecture and grain yield. Zhengdan 958 (ZD958) and Denghai 605 (DH605) were used as experimental materials. Three different planting patterns were: mixture (M), random sowing after mixing seeds of the two hybrids in the same proportion; 1:1, one row of ZD958 and one row of DH605; and two monoculture systems, SZD958 and SDH605, as controls. A 3‐yr study demonstrated that the mixed cropping treatments (M and 1:1) at low density (LD) showed no significant difference on light transmission, leaf area index (LAI), canopy apparent photosynthesis (CAP), and canopy respiration (CR), compared with the two monocultures. However, at a medium and high density (MD and HD), mixed cropping was characterized with higher light transmission to the ear and lower layers of the canopy during grain filling than that of monoculture treatments, while no significant differences between M and 1:1 treatments. Moreover, mixed cropping treatments maintained a higher LAI, CAP, lower CR, and increased the whole and post‐silking dry matter accumulation. Grain yields were higher under mixed cropping at MD and high density (HD), while no significant differences between M and 1:1 treatments. Relative to SZD958 and SDH605, the grain yields in the M treatment were 10% and 8% higher at MD, and 7% and 5% higher at HD, respectively. Mixed cropping optimized the canopy structure, maintained higher LAI and CAP during the grain filling period, reduced respiration, and increased aboveground dry matter at maturity. These improvements also result in higher grain yield.Core Ideas Mixed cropping facilitated the formation of a high‐efficiency canopy structure. Mixed cropping delayed the rate of leaf senescence, maintained higher LAI and CAP during the grain filling period. Mixed cropping increased aboveground dry matter weight at physiological maturity, and ultimately led to higher grain yield, especially medium density.