Which plant growth regulators can promote fruit setting or thinning flowers and fruits?

1-Naphthyl Acetic Acid can stimulate cell division and tissue differentiation, increase fruit setting, prevent fruit drop, and increase yield.
During the flowering period of tomatoes, spray the flowers with 1-Naphthyl Acetic Acid aqueous solution at an effective concentration of 10-12.5 mg/kg;
Evenly spray the whole plant before cotton flowering and during the boll-setting period, which can play a good role in fruit and boll preservation.

Gibberellic Acid (GA3) accelerates the longitudinal growth of cells, promotes parthenocarpy and fruit growth, and sprays grapes before and after flowering, which has a good effect on reducing the shedding of grape flowers and fruits;
During the flowering period of cotton, spraying, spot coating or evenly spraying Gibberellic Acid (GA3) at an effective concentration of 10-20 mg/kg can also play a role in cotton boll preservation.

Forchlorfenuron (CPPU / KT-30) has cytokinin activity. When applied to melons and fruits, it can promote flower bud differentiation, preserve flowers and fruits, increase fruit setting rate, and promote fruit enlargement.
During the flowering period of cucumbers, use Forchlorfenuron (CPPU / KT-30) with an effective concentration of 5-15 mg/kg to soak melon embryos;
On the day of melon flowering or the day before, use Forchlorfenuron (CPPU / KT-30) with an effective concentration of 10-20 mg/kg to soak melon embryos;
On the day of watermelon flowering or the day before, use Forchlorfenuron (CPPU / KT-30) with an effective concentration of 7.5-10 mg/kg to apply to the fruit stalk, which has a fruit-preserving effect.

Thidiazuron (TDZ) can promote cell division, increase the number of cells, and enlarge the fruit.
After cucumbers bloom, use an effective concentration of 4-5 mg/kg to soak melon embryos;
On the day of melon flowering or the day before, use Thidiazuron with an effective concentration of 4-6 mg/kg to spray water evenly to improve the fruit setting rate.

Sodium Nitrophenolates (Atonik) is a fruit-preserving plant growth regulator that can promote cell protoplasm flow, improve cell vitality, accelerate plant growth and development, enhance stress resistance, and promote flowering and prevent falling flowers and fruits. For example, during the seedling, bud, and fruit-setting stages of tomatoes, use Sodium Nitrophenolates (Atonik) at an effective concentration of 6 to 9 mg/kg to spray evenly on stems and leaves with water. From the initial flowering stage of cucumbers, spray Sodium Nitrophenolates (Atonik) at an effective concentration of 2 to 2.8 mg/kg every 7 to 10 days for 3 consecutive sprays, which has the effect of preserving fruits and increasing yields. Triacontanol can enhance enzyme activity, photosynthetic intensity, and promote crop absorption of mineral elements, which can promote early maturity and preserve flowers and fruits. During the flowering stage of cotton and the 2nd to 3rd week thereafter, spraying the leaves with Triacontanol at an effective concentration of 0.5 to 0.8 mg/kg has the effect of preserving bolls and increasing yields. 

Some other mixed products also have the effect of preserving flowers and fruits. Such as Indole Acetic Acid (IAA), Brassinolide (BRs), etc., can activate plant cells, promote cell division and growth, and increase chlorophyll and protein content. After spraying, it can promote the growth and greening of fruit tree leaves, preserve flowers and fruits, increase fruit setting rate, and ultimately increase yield and improve quality. At the end of apple budding and after flowering, an effective dose of 75-105 g/hectare is used to spray water evenly on the front and back of the leaves, which can significantly preserve fruits and increase yield.

Naphthaleneacetic acid can interfere with the metabolism and transportation of hormones in plants, thereby promoting the formation of ethylene. It has the effect of thinning flowers and fruits when applied to apple, pear, tangerine, and persimmon trees; 6-benzylaminopurine, ethephon, etc. also have the effect of thinning flowers and fruits.
When using the above-mentioned plant growth regulators, it is necessary to strictly control the application period, concentration, and select suitable crops and varieties.