Application of plant growth regulators on fruit trees-Longan

1.Control shoots and promote flowering
In recent years, as the global temperature has increase, longan is prone to sprouting winter shoots, which is not conducive to flower bud differentiation, resulting in low and unstable yields. The treatment of longan shoot control and flower promotion has become an important measure for longan to achieve high and stable yields.

Paclobutrazol
During the physiological differentiation period of flower buds in late autumn and early winter, with the increase of concentration in the range of 500-2000 mg/L, the extraction rate and roasting rate of longan are both higher.

6-BA+Daminozide
During the physiological differentiation period of longan (November-December), 6-BA 200mg/L+Daminozide 2000mg/L was used for 2 treatments, which reduced winter shoot shoots and significantly improved the flower spike rate and flower spike quality. After chemical treatment The shoot shoot ratio of drawn inflorescences is also significantly reduce.

Ethephon
Ethephon is generally spray with 300 mg/L Ethephon when the winter shoots are about to be extract. The inhibitory effect can last for 20-30 days. If the suppression is still not possible, another 250-300 mg/L Ethephon can be spray.

2 .Prevent longan from top branches flushing
The shoot refers to the developing longan flower spike. Due to the influence of external conditions, branches and leaves grow on the flower basket, forming a flower spike with leaves. If not treat in time, it will turn into a vegetative branch.

Ethephon
Special care should be taken when using Ethephon on longan. Its reaction to Ethephon is more sensitive than that of lychee. When applying it, the concentration must be flexibly controlled according to the tree condition and climatic conditions. If the concentration is too high, it will cause a large number of old leaves and flower spikes to fall off. Generally, in the early stages of shoot flushing, 150-250 mg/L Ethephon can be used to inhibit the growth of red leaves on the flower spike and the elongation of the terminal buds. Every 5- Spray once every 7 days and spray 2 times continuously.

Paclobutrazol(Paclo)
Spraying with 300mg/LP Paclobutrazol (Paclo) can inhibit the growth of red leaves, prevent shoot shoots, and promote the normal development of flower baskets.

Cytokinin 
When the main axis of the longan flower stalk is 5-6cm long, spraying 300-400 mg/L of cytokinin can promote the rapid development of the flower stalk and reduce the chance of shoot flushing.

3 .Fruit setting and fruit preservation
Longan fruit drop is very serious due to poor pollination and fertilization, conflicts between shoots and fruits competing for nutrients, nutritional deficiencies in the later stages, fruit cracking, and diseases and insect pests. 
Application of plant growth regulators can reduce longan physiological fruit drop, increase fruit setting rate, and promote longan fruit development. , plays the role of increasing fruit.

DA-6
Spray 8 to 15 mg/L of DA-6 once each during the flowering stage, after fruit setting and during the fruit expansion stage, which can increase the fruit setting rate, make the pulp thicker and sweeter, make the core smaller, enlarge the fruit, and increase yield.

CPPU / KT-30 
10 days after full flowering, soak the fruit stems and young fruits with 5-20 mg/L KT-30, which can increase the fruit setting rate, enlarge the fruits, and increase yield by about 50%.

Compound sodium nitrophenolate (Atonik)
Before flowering and after fruit setting, use 3-6mg/L compound sodium nitrophenolate (Atonik) for foliar spraying. Spray once every 7 days for a total of 3-4 times to increase the fruit setting rate and expand the fruit ,aslo increase yield.

Gibberellic Acid
Experiments show that spray 5-40mg/L 6-BA 7 days after the female flowers fade, or spray Gibberellic Acid 50mg/L+2,4-D 5mg/L mixture 25-30 days after the female flowers fade; 50-70 days later, that is, the second physiological fruit drop period, spray 10mg/LGibberellic Acid+2,4-D 5mg/L, or 10-50mg/L Gibberellic Acid, which can protect and strengthen the fruit.

Brassinolide (BR)
Spraying 0.01-0.05mg/L Brassinolide (BR) once at the harvesting and late flowering stages can effectively increase the fruit setting rate, single fruit weight and edible rate.