1. Plant hormones regulate many growth and developmental processes in plants such as stem elongation, root growth, flower development, fruit ripening, and leaf senescence. 2. There are five major classes of plant hormones: auxins, gibberellins, cytokinins, ethylene, and abscisic acid. Each has different functions in promoting or inhibiting growth. 3. Horticulturists apply plant growth regulators, which are synthetic versions of plant hormones, to regulate aspects of plant growth like promoting rooting in cuttings or preventing stem elongation. Maintaining adequate carbon dioxide levels is also important for optimal plant growth.

1. HORMON PERTUMBUHAN

2. 1. pertumbuhan bunga
2. Kematangan tumbuhan
3. Pertumbuhan akar
4. Megubah bentuk dan mematikan daun, batang dan bahagian lain.
5. Menghalang dan menggalakkan pemanjangan batang.
6. Mempengaruhi warna tumbuhan dan pencegahan pengguguran
daun

3.  Hormones are naturally produced by plant.
 Plant growth regulators are chemicals applied by a
horticulturist to regulate plant growth.
 In plant propagation , cuttings are dipped in a rottinh
hormone to stimulate root development. In house
production many potten flowering plant ( poinsettias,
easter lilies) maybe treated with plant growth regulator
to keep them short. Seedless grape are treated with
plant growth regulator to increase the size of fruit
• Regulators may be synthetic compound or may be
natural hormone that were accepted from plant tissue.

4.  Five group of plant growth-regulating compounds :
1. Auxin
2. Gibberelin (GA)
3. Cytokinin
4. Ethylene
5. Abscisca (ABA)
 They contain both naturally occuring hormone and
synthetic substances

5. AUXIN
 Bending towards light (phototropism)
 Downward root growth in response to gravity
(geotropism)
 Promotion of apical dominance
 Flower formation
 Fruit set and growth
 Formation of adventitious root
 Major site of auxin synthesis is apical meristem

6. GIBBERELLINS (GA)
 Cell division and elongation
 Break seed dormancy
 Speed germination
 Produced in the root growing tips stimulate shoot
growth
 If any seed that hard to germinate, just soaked them in
GA solution

7. CYTOKININ
 Founds both in plants and animals
 Stimulate cell division
 Produce by actively growing tissues, particularly roots,
embryos, and fruits
 Produced in roots and transported by xylem sap
 Use frequently in tissue culture

8. ETHYLENE
 Founds in gaseous form
 Induces ripening
 Causes leaves to drop
 Plant often increases in ethylene production in
response to stress
 Often found in high concentration within cells at the
end of plants life
 Leaf falls because of high ethylene

9. ABSCISIC ACID (ABA)
 General plant growth inhibitor
 Introduce dormancy and prevents seed
germination
 Causes abscission of leaves, fruits and
flowers
 Causes stomata to close

10. OTHER FACTORS
 FERTILIZATION
 The need to fertilize houseplant varies with rate of growth, ages
of the plant, desire for growth and growing season. Frequency of
feeding can vary from every 2 weeks to every several month
during the growing season. A general rule for application
frequency is fertilizing at half recommended strength, every 2
week from March to September. Do not fertilize most plant
during winter month. Winter reduce light and temperature
result in little or no growth. Most houseplants are dormant
during winter
 Houseplants fertilizers come in several form : granular,
crystalline, liquid, and tablet. Most are houseplants fertilizers are
fairly concentrated. Never exceed the recommended application
amount. Oftentimes, application should be even more dilute
than recommended. Label recommendation are based on the
ideal condition in greenhouse.

11. CARBON DIOXIDE(CO2) AND PLANT
GROWTH
 Carbon dioxide and water are combined with the aid of
light energy to form sugar. Some of these sugars are
converted into complex compounds that increase dry
solid plants substances for continued growth to final
maturity.
 However, when the supply of carbon dioxide is cut off,
or reduced, the complex plant cell structure cannot
utilize the sun’s energy fully and growth or
development is curtailed.

12.  The amount of CO2 in the air is only 0.03%
 This compare to 78% nitrogen, 21% oxygen and 0.97%
trace gases in normal air.
 The amount of CO2 are a plant requires to grow may
vary from plant to plant but test show that most plants
will stop growing when the CO2 level decrease below
150ppm
 Even at 220ppm, a slow down in plant growth is
significantly noticeable
 The lack of adequate CO2 lowers the average plant
yield quality and market value.

13. THE END