How are vegetable growth regulators used correctly?

Currently, the hormones (plant growth regulators) used in vegetable production mainly include 2,4-D, naphthalene acetic acid, indoleacetic acid, gibberellin, chlormequat, methyl naphthalene acetate, maleic hydrazide, ethephon, paclobutrazol, B9, etc. The application effects and methods of use of various hormones are briefly introduced as follows:

1. Hormones that can be selected to promote growth and improve vegetable quality: spraying gibberellin on leafy vegetables gives the best effect. For example, spraying 100 ml/kg of gibberellin once each 20 days and 30 days before harvesting celery can increase yield by 30%-50%.

2. Hormones that can be selected to promote fruit set and prevent flower and fruit drop: in early spring or late autumn, tomatoes can be treated with a 10 ml/kg to 25 ml/kg 2,4-D solution, dipping the flower pistil when the flowers have just opened. This not only prevents flower and fruit drop, but can also advance ripening by 10-15 days and increase the sugar content of the fruit.

3. Hormones that can be selected to break dormancy and promote germination: when spring potato tubers harvested in the same year are used as seed potatoes for autumn planting, they must go through a dormancy period. If the tubers are soaked in 0.5 ml/kg of gibberellin for 15-20 minutes, the dormancy period can be broken, promoting earlier germination and reducing seed potato rot.

4. Hormones that can be selected to promote rooting of cuttings: for growing and harvesting Chinese cabbage and cabbage, the leaf bud cutting method can be used to increase the propagation coefficient. The method is to quickly dip the leaf buds in a 1000-2000 ml/kg naphthalene acetic acid solution so that they take root and form independent plants. When propagating tomatoes by cuttings, dipping the base of the cuttings in 50 ml/kg naphthalene acetic acid or 100 ml/kg indoleacetic acid solution for 10 minutes can shorten the seedling raising time.

5. Hormones that can be selected to inhibit sprouting and extend the storage period of vegetables: for garlic and round onion, spraying the plants with 2500 ml/kg of maleic hydrazide 15 days before harvest allows them to be stored for 8 months without sprouting; for radish and carrot, spraying the plants with 100 ml/kg of 2,4-D 21 days before harvest can prevent bolting and extend the storage period; during storage of potatoes, spraying methyl naphthalene acetate can effectively inhibit sprouting.

6. Hormones that can be selected to prevent excessive vegetative growth and cultivate strong seedlings: when raising vegetable seedlings in early spring, applying 250-500 ml/kg of chlormequat to the soil can inhibit excessive seedling growth; when raising solanaceous vegetables in early spring, spraying 1000-2000 ml/kg of B9 on the leaves can make the seedlings shorter and sturdier and prevent excessive growth; at the early flowering stage of potatoes, spraying the plants with 250 ml/kg of paclobutrazol can promote lateral growth of the plants, prevent excessive growth, make the plants shorter and more compact, and make the leaves dark green.

7. Hormones that can be selected to control sex and promote more female ears: when zucchini seedlings have grown 3 true leaves, spray the plants with 150 ml/kg of ethephon, then spray once more every 10-15 days, for 3 times in total. This can increase the number of female flowers and advance maturity by 7-10 days. When cucumber seedlings have 4 true leaves, spraying the plants with 150 ml/kg of ethephon can also significantly increase the number of female flowers and raise yield.

8. Hormones that can be selected to promote ripening of melons and fruits: after tomatoes and peppers are harvested when they have turned color from green ripening, soak the fruit in a 2000 ml/kg ethephon solution for 1 minute, take them out and drain them, and place them at room temperature of 20-25°C; they will quickly turn red.

9. Hormones that can be selected to control bolting and flowering: dropping 20-50 ml/kg of gibberellin on the growing point of carrot, Chinese cabbage and celery can promote bolting and flowering in the same year. Spraying 4000-8000 ml/kg of chlormequat on cabbage and celery can inhibit bolting and flowering. At present, the use of this type of hormone is not advocated in the Shanghai area, and it is especially prohibited in the production of safe, hygienic, high-quality vegetables.