Abstract Background Due to decreasing production and high input costs, there has been an increased focus on optimizing planting density. Maintaining a consistent yield across multiple plant populations is a desirable way to cut costs. A two-year field experiment was conducted in Anyang, Henan, China (36°06′ N, 114°21′ E) at the Institute of Cotton Research, Chinese Academy of Agricultural Sciences, on clay loam soil, to evaluate the photosynthetic efficiency and light interception (bottom, middle, and upper canopy layers) response to different planting densities (D1, 15 000; D2, 33 000; D3, 51 000; D4, 69 000; D5, 87 000, and D6, 105 000 plants‧hm −2 ) for higher cotton yield. The study was conducted under the environmental conditions of average temperatures of 22.2 °C in 2019 and 21.5 °C in 2020, and rainfall of 318 mm and 392 mm in the respective years. Results The highest planting density (D6) produced the maximum leaf area index (LAI) and overall light interception in both years; however, excessive canopy density led to increased inter-plant competition and reduced yield efficiency. Although D6 had the highest LAI and light interception, the highest yield was observed at D5. This result is attributed to a more balanced canopy structure at D5, which optimized light distribution and photosynthetic efficiency, particularly in the middle and lower canopy layers, leading to better biomass accumulation and higher yield. Yield decreased at D6 due to reduced boll weight and lower reproductive efficiency. In contrast, D5 maintained a well-structured canopy with high and efficiently distributed light interception and improved photosynthetic performance, particularly in the middle and lower canopy layers. This optimized canopy architecture enhanced biomass accumulation in reproductive organs, resulting in 33% and 30% higher lint yield compared with the lowest density (D1) during the two experimental years, respectively. More seed cotton yield (4 449 kg‧hm −2 ) and lint yield (1 695 kg‧hm −2 ) resulted from D5, which is attributed to increased biomass accumulation in the reproductive organs. Conversely, the yield dropped as planting density (D6) continued to grow. Conclusion Therefore, the results showed that the cotton yield can be increased through high light interception rate and photosynthetic efficiency by adjusting planting density and the structure of the canopy.
Khan et al. (Fri,) studied this question.