Abstract: Rapeseed（Brassica napus L.） inbred lines “20ZY0592”（V1）, “20ZY9389”（V2）, hybrid variety “Huayouza 62”（V3） and “Huayouza 9”（V4） were used as test materials. A split-plot experiment with three densities of 3×10⁵ plants/hm²（D1）, 6×10⁵ plants/hm²（D2）, and 9×10⁵ plants/hm²（D3） was set up. The index of extinction, number of green leaves per plant, leaf area index, photosynthetic rate, agronomic characters and yield were measured at the overwintering period, budding period, full flowering period and silique period. The results showed that during the whole growth period of rapeseed, dense planting resulted in the increase of extinction index and leaf area index, the decrease of the number of green leaves per plant and photosynthetic rate. Under different density conditions, the extinction index and leaf area index, the number of green leaves per plant and photosynthetic rate were grouped in pairs, with positive correlation within groups and negative correlation between groups. Dense planting led to the decrease of root-stem diameter, effective branch number, effective length of main inflorescence, effective silique number per plant and the increase of effective branch position. Dense planting was beneficial to increase yield within a certain range, but led to decreased yield beyond the range. Reasonable dense planting was beneficial to increase the yield of rapeseed, but while dense planting increased the leaf area index, it would also lead to the increase of the extinction index, the decrease of the number of green leaves and photosynthetic rate of a single plant, and caused the individual plant to be thinner and center of gravity to rise, thereby increasing the risk of lodging, which needed to be paid attention to in the process of dense planting of rapeseed.

Key words: rapeseed（Brassica napus L.）, dense planting, growth, agronomic traits, yield