Gibberellin (GA)

1. What is Gibberellin (Gibberellin)? Origin of Gibberellin (Gibberellin):

Gibberellin (Gibberellin) is a plant hormone that regulates plant growth and affects a variety of developmental processes such as proliferating, germinating, sleeping, flowering, gene expression , enzyme stimulation and senescence of leaves as well as fruit etc.

Gibebrelin (Gibberellin) is the second phytohormone discovered after auxin

+ In 1989, Hori found out that Bakanae was caused by the Fusarium genus.

+ In 1935, Yabuta isolated Gibberellin (Gibberellin) A.

+ In 1938, Yabuta and Sumiki successfully crystallized Gibberellin (Gibberellin) A and B.

The scientists then found many other GA derivatives, nowadays there are about 136 GAs found, which are often isolated and crystallized from Gibberella fugikuroi and some other flowering plants.

Gibberellin (Gibberellin) is the most commonly used GA3 and GA1 active forms.

2. Gibberellin (Gibberellin)

Very diverse, more than 70 types of gibberellins (Gibberellins) are present in plants, microorganisms. Gibberelin (Gibberellin) was named according to the chronological order of GA1 detection. GA2 …. GAn, the most important of which is GA3. Gibberellins (Gibberellins) are all derivatives of gibbons.

                                                               The texture of some typical Gibberellin (Gibberellin)

3. Physiological role of Gibberellin (Gibberellin)

– Gibberellin (Gibberellin) stimulates cell proliferation:

GA stimulates cell proliferation (not by acid-producing mechanisms such as auxin), but in practice GA always appears with auxin – which can be prolonged by GA-dependent auxin.

– Gibberellin (Gibberellin) stimulates the growth of body height, length of branches, roots,

(vertical stretch of the cell):

               Effect of GA3 on stem elongation of short-stemmed apricot (left) seedlings of tree control (right) 7 days after GA3 treatment

The most pronounced physiological effect of Gibberellin (Gibberellin) is the strong stimulation of the prolonged growth of the body, the elongation of the alveoli. This effect is due to the Gibberellin (Gibberellin) strongly stimulate the vertical stretch of the cell. Therefore, when the treatment of Gibberellin (Gibberellin) for plants has accelerated the growth of nutrients should increase the biomass of plants. Under the influence of Gibberellin (Gibberellin) make the trunk grow very high height (green beans, soybean vinegar, jute 2 – 3 times higher).

-> The dwarf mutation (defective GA synthetic gene) – GA treatment will be very effective

– Giberelin (Gibberellin) stimulates cell division:

GA not only stimulates growth but also promotes cell division. GA stimulates cell division by initiating a number of cyclin-dependent protein kinases (CDKs) that play a role in regulating the cell cycle (transmitting cells from the G1 phase to the S phase)

– Gibberellin (Gibberellin) stimulates the germination, budding of the sprouts, seeds and tubers:

Gibberellin (Gibberellin) stimulates the germination, the budding of the germ, the seeds and the bulb, so it is effective in breaking down their sleep state. Gibberellin (Gibberellin) content usually increases at the time of shoots, bulbs, and leaves of the germinated seeds. In this case Gibberellin stimulates the synthesis of amilase enzymes and other hydrolysis enzymes such as protease, phosphatase …, and increases the activity of these enzymes, thus promoting the decomposition process. Powder into sugar as well as decompose polymers into other monomers, facilitating raw materials and energy for germination. Based on that, exogenous Gibberelin (Gibberellin) treatment can break the sleep state of seeds, tubers, onions, and even deep-rooted states.

– Stimulating flower and flower sex differentiation:

In many cases Gibberellin (Gibberellin) stimulates distinct flowering. The specific effect of Gibberellin flowering is to stimulate the long and rapid growth of the flower cluster. Gibberellin (Gibberellin) stimulates flowering plants in short day conditions (Lang, 1956).

Gibberellin (Gibberellin) affects the sexual division of flowers, inhibits the growth of female flowers and promotes the development of male flowers. Gibberellin (Gibberellin) is an auxin-like effect that increases the size of the fruit and produces seedless seeds. This effect is more pronounced when combined with auxin.

– Gibberellin (Gibberellin) stimulates fruit formation and produces seedless seeds (similar to auxin)

GA treatment increases the rate of fruiting and non-nutting fruits, increases fruit size, increases fruit yield. Both Auxin and GA must be present in the fruit in order to have fruit. Some crops (grapes, cherries, etc.) have specific reactions to GA.

4. The relationship of Gibberellin (Gibberellin) to auxin:

In most cases, GA has additional activity for auxin:

– Auxin stimulates the floor, GA stimulates tissue synthesis.

– Auxin stimulates cell proliferation of cells derived from histiocytes (under the apex, prolonged regions); GA stimulates the proliferation of cells derived from fecal calcified tissue.

– Auxin bumps armpit; GA stimulates shoot growth and removes the sleep of shoots and embryos.

Auxin stimulates root formation; GA does not have this effect (sometimes with inverted effect).

CHICKEN

Auxin
Structure

synthetic

Physiological effect

Stimulate the prolonged growth of the plant

Stimulate cell growth in all directions
5. Some applications of Gibberellin (Gibberellin)

GA has been extensively used in agricultural production and has yielded great effects such as stimulating plant growth to increase yields (as with leafy vegetables), stimulate rapid flowering and more, limiting flower loss, dropping young fruit and increasing the size of fruit (with fruit trees), stimulating seed germination (with rice …) and many other applications. For each tree group, GA can be used according to purpose.

– For rice: GA is used to stimulate seed germination, stimulate tillering, stimulate cotton flow and restrict choking cotton.

– For sugarcane: Spraying in the beginning of the long and sluggish stage, can increase productivity by 20 – 30%. GA spray for jute can increase tree height by 2 times.

– For leaf vegetables: vegetables such as spinach, spinach, spinach … spray 2 – 3 times in the period of strong growth can increase productivity over 30%.

– For coffee, cashews and fruit trees: (label, cloth, mango, rambutan, apple, milk …) to stimulate flowering, rapid and simultaneous spraying of GA when flower buds begin to form , about 20 to 30 days before the main flowering or after the flowering treatments (for drought, barking or spraying, irrigation), GA also increases the rate of bean Fruit, limited fall flowers and young fruit.

A result of research of Nong Lam University. Ho Chi Minh City showed that when spraying GA for coffee at the beginning of the flower stage, 80% of the flower bloom is concentrated for a short time of 15 – 20 days.

– Spray GA when the fruit begins to grow large fruits, large fruits and less fall. In many countries, GA is very popular to increase the yield and quality of grapes, which can make seeds less grainy or seedless. Spray the grapes two times when new shoots sprout and when the new fruit forms.

– Spray GA on the leaves and fruits when the fruit is about to mature to anchor on the tree, slowing harvest time to expand or wait for high prices, with citrus, lemon can be harvested monthly.

The University of Agriculture of Hanoi has successfully investigated the break-up method for potato harvest winter harvest to seed the spring crop by spraying GA solution, germination rate reached over 90% in 5 – 7 days.

In addition to these common uses, GA is also used for a variety of purposes, including the creation of male flowers in seed production, salad dressing, cabbage, short time for flowering flowers (daisy, lilies, lay …). In brewing, GA is used to stimulate seed germination for wheat, rye, corn, reduce yeast production costs, increase yeast quality, and shorten yeast time. It is estimated that about 50% of the world’s GA production is used in the technology of brewing.

In addition to GA3 which has been in widespread use, GA4 and GA7 have recently been discovered and used for crops. GA4 and GA7 are full of features and uses like the GA3, but use in practice is more convenient and safe. GA3 treatment of tall trees but not horizontally increase so fragile, fragile, easily broken. Moderate GA4 and GA7 treatment with moderately balanced, firmly balanced GA4.

In our country, Gibberellin preparations are mostly GA3.

As with other plant growth regulators, GAs exhibit efficacy with plants at very low doses, and additive on the plant characteristics and timing of use. Do not increase the dose and use the correct technique to use high efficiency and not adversely affect the plant. Pay attention to the combination of water supply and nutrition as required. GTPs (LD₅₀> 15.000 mg / kg oral LD₅₀), although less toxic to humans, should be used in isolation.