Abstract: In this paper, a split-plot experiment was designed to study the effects of different planting densities and row spacing modes on filling rate and grain quality of a summer maize variety ZD958. Four planting densities were 93 000, 81 000, 69 000 and 57 000 plants/hm², respectively. Three row spacing modes were one plant per spot with equal row, three plants per spot with equal row and three plants per spot with wide and narrow row, respectively. The results indicate that grain filling process did not significantly change with planting density increase while row spacing mode probably affected grain filling under the same planting density. Neither planting density nor row spacing significantly influenced crude protein and fat content, while higher planting density, such as 93 000 plants/hm², could significantly decrease soluble sugar content and sucrose content. The cropping pattern of three plants per spot with wide and narrow row could significantly decrease sucrose content. Therefore, it was concluded that in order to increase the economic benefits of maize production, the planting density and row spacing mode should be adjusted in accordance with the requirement for yield or quality in practice.

Key words: summer maize, filling process, grain quality, planting density, row spacing