Abstract: To clarify the regulatory effects of different cultivar-density combinations on root growth in summer maize, a field experiment was conducted in 2022 and 2023. We examined the interactive effects of cultivar and planting density on root morphology of two cultivars of summer maize, with different maturity periods, Zhengdan 958 and Dika 517. Three planting densities were set as low density (60000 plants·hm^-2), medium density (75000 plants·hm^-2), and high density (90000 plants·hm^-2). The results showed that root weight density, root length density, and average diameter of Dika 517 under different planting densities increased by 3.7%-39.5%, 2.1%-19.9% and 2.0%-24.5%, respectively, compared to Zhengdan 958. Compared with low density, root weight density and average diameter decreased by 4.2%-40.4% and 2.7%-25.8%, respectively, under medium and high density planting conditions, while root length density increased by 3.2%-15.2%. Cultivar, planting density, year, and the interaction between cultivar and density had significant effects on root weight density, root length density, and average diameter of summer maize. The changes of root architectural parameters (β values) indicated that the vertical distribution of roots for Zhengdan 958 and Dika 517 deepened with increasing planting density. These findings provide valuable insights for the selection of maize cultivars and the optimization of planting density.

Key words: maize, cultivar, plant density, root morphology, root architecture parameter