Optimizing row spacing to boost maize yield via enhanced photosynthesis and post-silking biomass allocation

Optimizing canopy architecture enhances photosynthetic productivity. Allocation of assimilates to the grains is promoted by optimizing canopy architecture. Balancing source-sink relationships and increasing yield require optimizing canopy architecture. High-density planting can better utilize the yield potential of modern varieties. However, under traditional row spacing conditions, increasing planting density brings about poor light distribution and limited yield improvement, highlighting the need for further exploration of optimal row spacing in relation to planting density. To assess the effect of delaying leaf senescence in the lower canopy by changing row spacing on the photosynthetic performance of the canopy and its regulatory impact on yield. A two-year field trial (2019-2020) was conducted on Zhengdan 958 for this study. Four treatments were set up: LR60 (6.75 plants m −2 , 60 cm row spacing, conventional planting); HR60, HR80, and HR100 (8.25 plants m −2 , with row spacings of 60, 80, and 100 cm, respectively). Quantitative analysis was conducted on canopy structure, population photosynthesis, and grain yield. Maize canopy leaf area index (LAI), photosynthetically active radiation (PAR), canopy apparent photosynthesis (CAP), biomass distribution, yield were measured. The results showed that the high-density treatments significantly increased the yield compared to LR60. Among the high-density treatments, HR80 exhibited an average yield increase of 8.47% compared to HR60 over two years. This was primarily attributed to HR80 enhancing the utilization of photosynthetically active radiation in the lower canopy after silking, delaying the decrease of LAI in the layers below the ear, and increasing CAP, resulting in a significant increase in biomass. HR80 increased yield by an average of 8.17% over HR100, due to significant increase in RUE during the grain-filling period. Furthermore, HR80 showed a significant increase in source-sink ratio compared to both HR60 and HR100, as well as an increase in 13 C-photosynthetic products partitioning to the grains, and a significant increase in kernel number. Thus, row spacing configuration should be adapted to the planting density for optimal yield. Specifically, appropriate row spacing can optimize the population structure, enhancing light distribution within the middle and lower canopy layers, and improving the canopy apparent photosynthesis and light utilization, which will support higher yields in maize.