| To investigate the effects of different row spacing configurations, planting densities, and their interactions on post\|flowering photosynthetic characteristics and yield of sorghum, a field experiment with a split\|plot design was conducted from 2023 to 2024. The main plots included three row spacing configurations: uniform spacing (60 cm, S1), wide\|narrow rows (80 cm + 40 cm, S2), and wide\|narrow rows (90 cm + 30 cm, S3), while subplots comprised three planting densities: 75 000 plants·hm-2 (D1), 105 000 plants·hm-2 (D2), and 135 000 plants·hm-2 (D3). A total of nine treatments were established. Parameters included stem\|leaf angles at different canopy positions, single\|plant leaf area, leaf area index, leaf area decay rate, canopy photosynthetic potential, photosynthetic parameters (net photosynthetic rate Pn, transpiration rate Tr, intercellular CO2 concentration Ci, and stomatal conductance Gs), and yield components were analyzed. The results showed that row spacing configurations and planting densities significantly influenced the stem\|leaf angles of middle and lower leaves, net photosynthetic rate, transpiration rate, stomatal conductance, 1 000\|grain weight, and yield of sorghum. Their interaction exhibited significant positive regulatory effects on the stem\|leaf angles of middle leaves, 1 000\|grain weight and yield. Yearly variations significantly affected grains per panicle, 1 000\|grain weight, and yield. At the same row spacing comfiguration, when S2 configuration was combined with D2 density, the stem\|leaf angle of the middle leaves was significantly reduced by 3.68%, and canopy photosynthetic potential and grain yield were significantly increased by 36.58% and 12.23%, respectively, compared to D1. Relative to D3, D2 decreased leaf area decay rate (14-49 days post\|flowering) and flowering\|stage Ci by 16.92% and 32.79%, while enhancing single\|plant leaf area (0-49 days post\|flowering), Pn, Tr, Gs, 1 000-grain weight, and yield by 23.07%, 13.73%, 13.54%, 18.70%, 6.71%, and 4.91%, respectively. At the same planting density, when D2 density was combined with S2 configuration, the single\|plant leaf area (0-49 days post\|flowering), canopy photosynthetic potential (28-35 days post\|flowering), 1 000-grain weight, and yield was increased by 6.70%, 7.19%, 3.73%, and 5.85% compared to S1, while leaf area decay rate was reduced by 10.46% versus S3. Mid\|leaf stem\|leaf angles, leaf area index (49 days post\|flowering), Pn, and Tr at flowering stage were elevated by 24.19%, 9.94%, 7.17%, and 12.75% over S1 and by 10.12%, 7.28%, 6.18%, and 11.20% over S3. In conclusion, the planting combination of wide\|narrow row spacing (80 cm + 40 cm) with a planting density of 105 000 plants·hm-2 can achieve high and stable yield by optimizing canopy structure, enhancing photosynthetic performance, and delaying leaf senescence,with yield increased by 3.18% to 16.19% compared with other combinations. Thus, it is recommended as an optimal sorghum cultivation model for popularization in dry farming areas in eastern Inner Mongolia and similar ecological regions. |