(2) Main principles: increase RNA and DNA content, improve RNA polymerase activity, increase ATPase activity, strengthen the role of auxin and promote growth.

(3) Main products: 0.0075%, 0.004% brassinolide aqueous solution, 0.0 1% brassinolide emulsifiable concentrate and 0.0 1% brassinolide soluble solution.

(4) Key application techniques ① Application period: two-leaf one-heart period to three-leaf one-heart period after transplanting or direct seeding of Chinese cabbage.

② Dose A: 0.0 1% brassinolide EC 2500 ~ 5000 times.

B: 0.0075% brassinolide aqueous solution 1000 ~ 1500 times.

③ Application method: spray the whole plant evenly 1 ~ 3 times, and the interval of each application is 10 ~ 15 days.

(5) Precautions ① Strictly follow the label and instructions, and do not increase the dosage at will.

② Spraying in the morning and evening. 6 hours after spraying, if it rains, it needs to be sprayed again.

③ It can be mixed and sprayed with pesticides such as pesticides and fungicides.

④ Fertilizer and water management of crops should be strengthened after pesticide application to give full play to the potential of increasing production.

⑤ Used containers should be properly disposed of, and cannot be used for other purposes or discarded at will.