Gibberellin, also known as gibberellic acid, is a broad-spectrum plant growth regulator. It is widely used in fruit trees. It has the effect of accelerating plant growth and development and promoting cell elongation. It is often used to induce parthenocarpy and flower preservation. Fruit preservation and fruit preservation, etc.
Gibberellin can promote the transportation of nutrients to flowers and fruits, thereby promoting fruit setting, fruit development, and increasing fruit setting rate, so it can be used as a fruit-preserving agent.
Gibberellin is used as a fruit-preserving agent, and the application time is generally from the flowering period to the young fruit period of the fruit tree, and it is sprayed. The dosage and concentration depend on the number of fruit tree species.
(1) Pome fruit (pear, apple, hawthorn) and stone fruit (plum, peach, plum, apricot, jujube, cherry, loquat, bayberry): the concentration used is 10-50 mg/L.
(2) Persimmon and pomegranate: use a slightly higher concentration, generally 50-100 mg/L.
(3) Citrus: The concentration of citrus fruit trees is relatively wide, and 10-100 mg/L has a fruit-preserving effect, but the higher the concentration, the easier it is to induce coarse-skinned, large-sized fruits and the worse the quality. The maximum concentration should not exceed 100 mg/L. If the concentration exceeds this concentration, the fruit setting rate will be reduced, and there may be a slight drop of leaves.
The usual concentration is 30-50 mg/L in two sprays. Spray once when 2/3 of the flowers fade and before the second physiological fruit drop.
(1) The transfer of gibberellin in plants is slow, and it is easy to cause leggy shoots. Therefore, when using medicine, we must pay attention to the spraying position, aiming at the flower and fruit, spray more on the fruit, spray less on the less fruit, and do not spray on the fruitless place.
(2) It is better to add an appropriate amount of foliar fertilizer when spraying gibberellic acid, but alkaline foliar fertilizer cannot be used. The recommended mixed foliar fertilizers are: 0.3% to 0.5% urea or 0.2% ~0.3% potassium dihydrogen phosphate.
2. Flower control
The flower bud differentiation of fruit trees is related to the content of gibberellin in the tree. Spraying gibberellin to the crown during the physiological differentiation period of flower buds can inhibit flower bud differentiation and reduce the amount of flowers in the following year.
In citrus production, gibberellin can be used to control flower volume for plants with weak tree vigor and plants with few fruits in the current year and expected to be a big year in the following year.
The physiological differentiation period of citrus flower buds is from September to November. During this period, gibberellin is sprayed on the canopy at a concentration of 10-200 mg/L. The higher the concentration, the stronger the flower-inhibiting effect. If the flower bud differentiation period is missed, spraying from December to February of the following year can also play an inhibitory role. The commonly used concentration is 50 to 100 mg/L, spray 1 to 3 times, with an interval of 20 to 30 days.
(2) Bayberry and peach: The flower bud differentiation period is from June to August, the concentration of gibberellin used is 20-50 mg/L, and the spraying is performed 3 to 4 times with an interval of 10 days.
3. Anti-cracking fruit
Citrus and pomegranate are prone to cracking before picking, or prolonged drought and rain can also cause peels to crack.
In addition to some methods such as water and fertilizer management, the use of gibberellin can also prevent fruit cracking.
Spraying fruit with gibberellin before or during fruit splitting can stimulate the growth of the peel, thicken the peel, and enhance toughness, thereby reducing fruit splitting. Use the concentration of 20-30 mg / liter, spray on the fruit surface.
(1) Pre-harvest treatment: spraying gibberellin before fruit picking can delay fruit coloring and senescence, enhance disease resistance and storability, delay ripening, and prolong tree hanging period, thereby adjusting the market supply period.
①Citrus: Before harvesting, when the peel begins to turn from green to yellow, gibberellin can be sprayed on the crown of the tree in combination with disease prevention at a concentration of 10-20 mg/L, sprayed twice with an interval of 20-30 days.
②Persimmons: Before harvesting, when the green turns to yellow at the beginning, the spraying concentration is 25-50 mg/L, which can also slow down softening and prevent rot.
③Plum and plum: 15 to 25 days before fruit picking, the spraying concentration is 50 mg/L.
(2) Post-harvest treatment: Mycin can delay fruit senescence, and soaking the fruit or ear of gibberellin after fruit picking can maintain the hardness of the peel, improve the storage effect and prolong the storage time.
①Citrus: 15-100 mg/L of gibberellin is used as an auxiliary agent, and it is mixed with antiseptic and fresh-keeping agent for fruit soaking treatment.
②Persimmon: Use 15-100 mg/L gibberellin to soak the fruit for 3-12 hours.
③Jujube: Use 30-50 mg/L gibberellin to soak the fruit for 1-2 minutes.
④Banana: soak the ear with 100 mg/L gibberellin.
5. Promote root growth
(1) Citrus: foliar spraying of gibberellin in the growing season of citrus seedlings can promote vegetative growth and strengthen the seedlings. The concentration is 50-100 mg/L, and the effect is better when mixed with 0.5% urea solution. This method can also play a role as a strong tree for the result tree with weak vigor.
(2) Strawberry: When 2 to 3 new leaves of strawberry are pumped, spray 100 mg/L gibberellin, which can advance the occurrence time of stolons, increase the occurrence number, increase leaf area, and enhance growth. Traditional Chinese are more commonly used.
(3) Grapes: Spray 5-10 mg/L gibberellin during the budding stage of grapes, which can speed up the growth of new shoots and inflorescences. Varieties with tighter ears can also be used to lengthen the rachis and loosen the ears.
6. Induce parthenocarpus in grapes
Gibberella can make seedless varieties seedless and promote fruit enlargement of seedless grape varieties.
The use of gibberellin to induce parthenocarpus in grape production generally requires two treatments:
(1) The first treatment: 10-20 mg/L of gibberellin is sprayed or dipped in the ear from about 3 days before the grape flowers to the full flowering period, which can make the pollen and ovule of the nucleated variety abnormally develop, and make them free from damage. nucleus, induces parthenocarpy.
(2) The second treatment: about half a month after the grapes are in full bloom, use 20-50 mg/L gibberellin to spray or dip the fruit ears. For seedless varieties, the concentration should be increased to 100 mg/L, and 5-8 leaves should be left above the inflorescence for topping treatment to promote fruit size.
7. Prevent falling leaves
In the growing season of fruit trees, in addition to the control of diseases and insects, gibberellin can be sprayed with 10-50 mg/L of gibberellin in combination with the top dressing outside the roots to enhance the function of leaves and reduce the loss of leaves.
Matters needing attention: In case of flower bud differentiation of fruit trees, try not to use this method. If it is used, the concentration of gibberellin should be reduced to less than 10 mg/L, so as not to inhibit flower bud differentiation and reduce flowers and yield.