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Application of plant growth regulators on fruit trees - Litchi

Date: 2023-08-22 14:16:58
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Section 1:Technical measures to control shoots and promote flowers.

The principle of lychee shoot control and flower bud promotion is that according to the requirements of the flower bud differentiation period of different varieties, the shoots should be pumped 2 to 3 times at the right time after harvest, and the winter shoots can be controlle to promote flower buds after the last autumn shoots turn green or mature.
differentiated management measures.     

 The use of plant growth regulators can successfully control the germination of litchi winter shoots, promote flowering, increase the flowering rate and the proportion of female flowers, cultivate strong flower spikes, and lay a good material foundation for flowering and fruiting in the following year.      ​

1.Naphthalene acetic acid(NAA)

(1)Naphthalene acetic acid(NAA)
When lychee grows too vigorously and does not differentiate into flower buds, use 200 to 400 mg/L Naphthalene acetic acid (NAA) solution to spray on the whole tree to inhibit the growth of new shoots, increase the number of flower branches and increase fruit yield.      ​

(2) Paclobutrazol (Paclo)
Use 5000mg/L Paclobutrazol (Paclo) wettable powder to spray the newly drawn winter shoots, or apply paclobutrazol to the soil 20 days before the winter shoots germinate, 4g per plant, to inhibit the growth of winter shoots and reduce the number of leaves. making the crown compact, promoting heading and flowering, and increasing the proportion of female flowers.

Section 2: Prevent tip rush
After the flower spike "shoots", the formed flower buds will shrink and fall off, the spike rate will be reduce, and they may even completely turn into vegetative branches.     
Litchi "shooting" will cause yield reduction to varying degrees, or even no harvest, and has become one of the important reasons for lychee harvest failure.

1. Ethephon 2.Paclobutrazol(Paclo)

For lychee trees with severe flower spikes and leaves, you can spray 40% ethephon 10 to 13 mL and 50 kg of water until the leaf surface is moist without dripping liquid to kill the leaflets and promote flower bud development.     

When using ethephon to kill small leaves, the concentration must be controlled.If it is too high, it will easily damage the flower spikes.      
If it is too low, the effect will not be good. Use low concentration when the temperature is high.

(2)Paclobutrazol(Paclo) and Ethephon
Treat 6-year-old litchi tree with 1000 mg/L Paclobutrazol (Paclo) and 800 mg/L Ethephon in mid-November, and then treat it again 10 days later, which significantly improves the flowering rate of the plants.

Section 3 :Preserving Flowers and Fruits
Lychee buds fall off before they bloom.  The female flowers of lychees may fall partly due to lack of fertilization or poor pollination and fertilization, and partly due to insufficient nutrient supply.  Only female flowers with good pollination and fertilization and sufficient nutrition can develop into fruits.

Technical Measures for Preserving Flowers and Fruits
(1)Gibberellic acid(GA3) or Naphthalene acetic acid(NAA)

Use gibberellin at a concentration of 20 mg/L or Naphthalene acetic acid (NAA) at a concentration of 40 to 100 mg/L 30 days after the lychee flowers fade.
Solution spraying can also reduce fruit drop, increase fruit setting rate, increase fruit size, and increase yield.   30-50mg/L Gibberellic acid (GA3) can reduce mid-term physiological fruit drop, while 30-40mg/L Naphthalene acetic acid (NAA) has a certain effect on reducing pre-harvest fruit drop.

Use 200~400mg/L Ethephon during the budding period (i.e. early to mid-March)
The solution can be spray on the whole tree, which has a good effect of thinning flower buds, doubling the number of fruits, increasing the yield by more than 40%, and changing the situation of more lychee flowers and less fruits.
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