Uses of Plant Growth Regulators (Gibberellins) in fruit orchards

1. Plant Growth Regulators
(Gibberellins)
Prof. Dr./ Galal Ismail Eliwa
Head Of Pomology Department
Faculty Of Agriculture
Damietta University
E. mail/ geliwa2002@du.edu.eg

2. Gibberellins
 Gibberellins are plant hormones that promote
growth, seed germination and leaf expansion.
They occur at low concentrations in vegetative
tissues but at higher concentration in
germinating seeds.
Induce cell elongation and cell division.
Important for plant growth and development
through flowering and/ or seed germination.
3/1/2020 Galal Eliwa 2

3. Gibberellins
3/1/2020 Galal Eliwa 3
 Discovered by Kurosawa, a Japanese Plant
Pathologist in 1928.
 Rice plants infected by the fungus Gibberella
fujikuroi showed excessive stem elongation.
 Symptom is called “Bakane” diseases “foolish
seedling” .
 Chemical was extracted & purified and names as
Gibberellic Acid (GA)
 Now 84 different Gibberellins are available – GA1
to GA84.
 The most commonly occurring gibberllinis is GA3

4. 3/1/2020 Galal Eliwa 4

5. Gibberellins
3/1/2020 Galal Eliwa 5

6. Gibberellins
3/1/2020 Galal Eliwa 6

7. Gibberellins
• Site:
 Are produced in the shoot apex primarily in the leaf
primordial (young leaves), roots, and developing
seeds (developing endosperm) and fruits.
Transport:
Made in the tissue in which it is used.
Transport occurs through Xylem, Phloem, or cell to
cell.
Phloem seems to be most important route.
 Transport is not polar, as it is for Auxin.
3/1/2020 Galal Eliwa 7

8. Gibberellins Actions
Promotes stem elongation:
 Stimulates cell division, cell elongation (or both) and
controls enzyme secretions.
 EX: dwarf cultivars can be treated with GA and grow to
normal heights – indicates dwarf species lack normal
levels of GA.
dwarf = short.,
wild type = tall;
dwarf + GA = tall
 Thus, GA application:
1. stimulates elongation; and
2. acts on intact plants.
3/1/2020 Galal Eliwa 8

9. Gibberellins Actions
3/1/2020 Galal Eliwa 9
1- Promotes stem elongation:

10. 3/1/2020 Galal Eliwa 10
Gibberellins Actions: in Tissue culture

11. 3/1/2020 Galal Eliwa 11
Gibberellins Actions in Tissue culture

12. Gibberellins Actions
2- Overcomes dormancy in seeds:
 Gibberellins also have a fundamental role in breaking
seed dormancy and stimulating germination.
 The endosperm of many seeds contains protein and
carbohydrate reserves upon which a developing
embryo relies for energy and nutrition.
 These reserves must be mobilized and transported to
the embryo.
 A range of hydrolytic and proteolysis enzymes break
down endosperm starches and proteins into smaller,
more easily transported molecules, such as sugars and
amino acids.
3/1/2020 Galal Eliwa 12

13. Gibberellins Actions
Overcomes dormancy in seeds:
• Seed germination may require gibberellins for the
activation of vegetative growth of the embryo.
Gibberellin application also activates the alpha
amylase synthesis in the aleurone layer where it
converts starch to sugar which translocated to
growing embryo to provide energy source.
3/1/2020 Galal Eliwa 13

14. 3/1/2020 Galal Eliwa 14
Gibberellins Actions: improving germination
‫البذور‬ ‫سكون‬ ‫كسر‬ ‫فى‬ ‫الجبريللين‬ ‫استخدام‬
‫االنبات‬ ‫ونسبة‬ ‫سرعة‬ ‫لتحسين‬

15. 3/1/2020 Galal Eliwa 15
Gibberellins Actions: improving seeds germination

16. Gibberellins Actions
Involved in parthenocarpic fruit development:
3/1/2020 Galal Eliwa 16

17. Gibberellins Actions
 Gibberellins stimulate the stalk length of seedless grapes
to grow longer, thereby alleviating compaction and it
promotes elongation of the fruit.
3/1/2020 Galal Eliwa 17
GA can induce fruit enlargment:

18. )‫(الجبريللين‬ ‫النباتية‬ ‫النمو‬ ‫منظمات‬ ‫استخدام‬
‫العنب‬ ‫مزارع‬ ‫فى‬
3/1/2020 Galal Eliwa 18

19. 3/1/2020 Galal Eliwa 19
Gibberellins stimulate the stalk length of seedless grapes
to grow longer, thereby alleviating compaction and it
promotes elongation of the fruit.

20. 3/1/2020 Galal Eliwa 20

21. 3/1/2020 Galal Eliwa 21

22. 3/1/2020 Galal Eliwa 22
Gibberellins Actions: improving pome fruit set
:
•‫أسد‬ ‫بالجبريلك‬ ‫الرش‬ ‫بإستخدام‬ ‫األنا‬ ‫تفاح‬ ‫أشجار‬ ‫على‬ ‫العقد‬ ‫نسبة‬ ‫زيادة‬ ‫يتم‬(
‫البريليكس‬)‫من‬ ‫بتركيز‬5-10‫المليون‬ ‫فى‬ ‫جزء‬(3-6‫قرص‬/600‫ماء‬ ‫لتر‬)‫على‬
‫حوالى‬ ‫الى‬ ‫التزهير‬ ‫نسبة‬ ‫تصل‬ ‫عندما‬ ‫الرش‬ ‫يتم‬ ‫ان‬50-75%
•‫شمسية‬ ‫شكل‬ ‫وعلى‬ ‫منخفض‬ ‫الموتور‬ ‫ضغط‬ ‫يكون‬ ‫أن‬ ‫مراعاه‬ ‫مع‬

23. Gibberellins Actions
3/1/2020 Galal Eliwa 23
• Promotes cell division & elongation
Red Delicious apples untreated (Left) and treated with a combination
of benzyladenine, a cytokinin, and GA4 + GA3 (Right).
Note: The elongated almost pointed shape.

24. Gibberellins
Among various growth regulators, the role of
gibberellins is definitely more important in the setting
of fruits because many experiment with gibberellins
spray on the flowers have shown enhancement in
fruit set.
The gibberellins have been used in improving fruit set
with greater promise as compared to auxins in pome
fruits. GAs induced fruit set either with mature or
immature embryo sacs and differences in fruit-set
were related to the stage of nucleus development at
the time of application.3/1/2020 Galal Eliwa 24

25. Gibberellins Actions: improving pome fruit set
‫تحسين‬‫فى‬ ‫العقد‬‫الجبريللين‬ ‫باستخدام‬ ‫الكمثرى‬
•‫الجبرالين‬ ‫رش‬‫بمعدل‬10‫عند‬ ‫المليون‬ ‫فى‬ ‫جزء‬30%
-40%‫تزهير‬.
•(1‫قرص‬/100‫العقد‬ ‫ثبات‬ ‫فى‬ ‫للمساعدة‬ ‫ماء‬ ‫لتر‬
‫بذرة‬ ‫بدون‬ ‫البكرى‬.)
3/1/2020 Galal Eliwa 25

26. 3/1/2020 Galal Eliwa 26

27. 3/1/2020 Galal Eliwa 27

28. 3/1/2020 Galal Eliwa 28

29. 3/1/2020 Galal Eliwa 29

30. 3/1/2020 Galal Eliwa 30

31. Gibberellins Actions
• Flowering:
 GA stimulates bolting in Long Day plants and can substitute for
long days or cold treatments that are necessary for flowering.
3/1/2020 Galal Eliwa 31

32. Gibberellins Actions
• Sex expression:
 In plants with separate male and female
flowers, GA application can determine sex.
For example, in cucumber and spinach, GA
treatment increases the proportion of male
flowers for seed production.
In maize, GA treatment causes female flower
development.
3/1/2020 Galal Eliwa 32

33. Gibberellins Actions
• High sugar yield:
 Growing of sugarcane
enhances the growth of
internodes and increase
the crop productivity &
sugar yield of crop.
3/1/2020 Galal Eliwa 33
In citrus fruits, gibberellins
delay senescence, GAs sprays
might have triggered auxin
level and nullified the action of
ABA

34. Effect of pre-sowing seed treatment
with bio-regulators (GA3)
3/1/2020 Galal Eliwa 34

35. Effect of Gibberellins on fruit set and
development
3/1/2020 Galal Eliwa 35