Figure 1.

The net photosynthetic rate (Pn) of the two maize hybrids under different planting densities in (A) 2019 and (B) 2020. 958 denotes Zhengdan958 and 335 denotes Xianyu335. D1: 45,000 plants ha⁻¹; D2: 67,500 plants ha⁻¹; D3: 90,000 plants ha⁻¹; D4: 112,500 plants ha⁻¹. Values were presented as the means of two replicates ± standard error (SE). Different letters above the bars indicate significant differences between different densities at the 0.05 level. ** indicate significant differences at the 0.05 and 0.01 levels, respectively.