Optimum leaf excision increases the biomass accumulation and seed yield of maize plants under different planting patterns

Without developing new agronomic practices, present rates of improvement in seed yields of cereal crops globally are insufficient to fulfil the estimated increasing food demand for 2050 and beyond. Intercropping is one of the agricultural practices that can lead to greater crop yields. However, there exists leaf redundancy for maize in intercropping systems, and the top canopy leaves shade more competent leaves at middle strata of maize plants. Therefore, this work aimed to elucidate the effect of leaf excision treatments in maize to understand the optimum leaf area of maize plants under a maize–soybean relay‐intercropping system (MSR) and a sole cropping system (SM). The effects of four‐leaf excision treatments (T₁, 0; T₂, 2; T₃, 4; T₄, 6 leaves excised from the top of maize plants until 7 days after silking) on light interception, leaf area index (LAI), photosynthetic characteristics, total biomass accumulation at blistering stage (BS), dough stage (DS) and physiological maturity (PM), and seed yield of maize were investigated through field experiments for 2 years under MSR and SM. Results showed that, under MSR and SM, as compared to control (T₁), optimum excision of leaves (T₂) from the top of maize plants significantly improved the light interception (by 25, 18 and 16% at BS, DS and PM, respectively) to lower strata leaves and accelerated the biomass partitioning to maize seeds (by 13 and 12% at DS and PM, respectively). Importantly, plants under T₂ exhibited higher green leaf area than control, that is, excision the top two leaves led to an increase in LAI at PM by 10%, suggesting that leaf senescence under T₂ was delayed which enhanced the photosynthetic rate at PM by 7% in 2017 and 6% in 2018. Relative to T₁, maize under T₂ produced 19 and 13% higher maize yield under MSR and SM, respectively, and relay‐cropped maize had 90% of SM seed yield. These results suggest that by manipulating the canopy structure of maize plants we can enhance the biomass accumulation and seed yield of maize crops under MSR and SM.