Effect of planting density on production performance and photosynthetic characteristics of Avena sativa ‘Baiyan No.7’ in Western Songnen Plain

A theoretical basis was provided to determine the suitable planting density for high yield cultivation of Avena sativa ‘Baiyan No.7’ in the Western Songnen Plain. Baiyan No.7 was chosen as the material to explore the effects of six density levels (D₁: 3 million plant·ha^–1, D₂: 4.5 million plant·ha^–1, D₃: 6 million plant·ha^–1, D₄: 7.5 million plant·ha^–1, D₅: 9 million plant·ha^–1, and D₆: 10.5 million plant·ha^–1) on production performance and photosynthetic characteristics. The results showed that with the increase in planting density, the phenological characteristics of Baiyan No.7 were enhanced, and the growth duration was shortened. The plant height and stem diameter of latter stages decreased significantly with the increase in planting density (P < 0.05). The tiller number of each growth stage decreased significantly with the increase in planting density (P < 0.05). The effect of planting density on oat leaf area index (LAI) was significant (P < 0.05), and with increasing density, the LAI of oat increased from the tillering period to the anthesis period. The change from the anthesis period to the milk-ripening period first showed an increasing trend and then decreased. Planting density had a significant effect on photosynthetic potential at each growth stage and total photosynthetic potential (P < 0.05). With increasing density, the photosynthetic potential first increased before the booting period, and then decreased after the booting period, and the total photosynthetic potential first increased and then decreased. During the anthesis period, the photosynthetic performance of flag leaves decreased significantly with increasing density (P < 0.05). The planting density had a significant effect on the fresh yield and hay at each growth stage (P < 0.05). In most sampling periods, the yields of both fresh oat and hay showed a tendency to first increase and then decrease with the increase in planting density, and reached the highest yield in the D₅ treatment. In the different growth periods, the yield of fresh oat and hay was the highest at the milk-ripening period. In this study area, the suitable planting density of Avena sativa ‘Baiyan No.7’ was 9 million plant·ha^–1, and the best harvest was at the milk-ripening period.