Abstract: With broccoli variety Tailu No.1 as materials, the growth status of broccoli seedlings was observed continuously. The growth dynamic processes of plant height, stem diameter, fresh weight and dry weight were fitted by Logistic equation, and the Logistic growth model, phenology and growth characteristic parameters were obtained. The results showed that the growth variation regularity of broccoli seedlings in different growth indicators are basically the same, in line with S-shaped growth curve, and the coefficient of determination (R²) was more than 0.981. Each index entered the fast growth period and the slow growth period on 8 d and 33 d after sowing, respectively. Linear growth of the fast growth period accounted for more than 60% of the total amount of growth. According to the Logistic curve, three phases of accelerating growth, fast growth and slow growth were accurately divided during broccoli seedling period. The correlation coefficient of the model validation indicated the reliability of broccoli seedling growth model. By using the Logistic equation, the dynamic growth of broccoli seedlings could be fitted. The fertilizer and water management should be strengthened in fast growth period of seedlings (20-33 d after sowing); and the transplantation should be carried out on 33 d with four leaves.

Key words: broccoli, Logistic regression, growth model, seedling period