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Georgia Agriculture Education Curriculum
Course:
Unit 8:
01.461
General Horticulture
Plant Growth Regulators
Lesson 1: Growth Regulators
QCC: ................................................................................................................................. 430, 440
Objectives:
1. Name the major groups of plant growth regulators.
2. Describe the control of apical dominance by plant
hormones.
3. Describe the benefits of using plant growth regulators.
4. List the different types of rooting compounds.
5. Discuss using plant growth regulators to control the size of
flowering plants.
6. Explain the impact of growth regulators on lawn
maintenance companies.
7. Discuss timing of growth regulator application.
8. Explain gibberellins.
Teaching Time:
1 hour
References:
Schroeder, Charles B. Introduction to Horticulture: Science and Technology.
Interstate Publishers, Inc. Danville, IL.
Web Links:
http://extension.oregonstate.edu/mg/botany/hormones.html
http://www.ext.vt.edu/pubs/greenhouse/430-102/430-102.html
Materials and Equipment:
samples of growth regulators
growth regulator table
plants
Power Points:
Horticulture Unit 5 – Rebecca Johnson
Course: 01.461
General Horticulture
Revised August 1999
Unit 8, Lesson 1
1
Georgia Agriculture Education Curriculum
TEACHING PROCEDURE
Introduction and Mental Set
Introduce unit by showing students examples of plants grown with regulators
(Poinsettias, Easter lilies) and without regulators.
Discussion
1.
What are growth regulators?
Regulate or influence cell dimension, cell differentiation, root and
shoot growth, flowering, and senescence (plant aging)
2.
What are the 2 types of growth regulators?
A.
Promoters. Examples: auxins, hormones, gibberelli, cytokin,
ethylese
B.
Inhibitors. Examples: hormones, abscission acid
3.
What are gibberellin?
Simultaneous growth over more than auxin. Promotes cell elongation,
stimulate cell division and control enzyme release.
4.
Plant growth regulating compounds are divided into two groups.
A. Natural (hormone) - made by the plant and may inhibit or
promote growth.
B.
Synthetic (human made)
5.
What is Apical Domain?
Naturally occurring auxins. Terminal bud inhibits the development of
lower lateral buds.
6.
What are some benefits of using plant growth regulators?
A.
promote and accelerate root formation
B.
shorter stem length
C.
promote branching
D.
increase flower set
E.
increase maturing while left on tree
F.
prevents seed germination
G.
promotes or inhibits ripening after harvesting
7.
Complete growth regulator chart 8.1.1. Review each regulator, its
effects, and what crops to be used on.
Course: 01.461 General Horticulture
Revised August 1998
Unit 8, Lesson 1
2
Georgia Agriculture Education Curriculum
8.
What are some benefits of using growth regulators?
A.
accelerates root formation on cutting
B.
prevents plants from being >leggy= and becoming
unmarketable; i.e., chrysanthemum, Poinsettia, Easter lily
C.
improves the longevity and quality of cut flowers
D.
helps maintain cut flower quality and vase life
E.
turf industry uses to control vegetative growth and reduce
mowing
F.
eliminates unwanted sprouts and suckers in nursery/landscape
industry
G.
regulates size of trees ans shrubs
H.
reduces pollen production in landscape
9.
When should growth regulators be applied?
A.
identify crops
B.
requirement for crops
C.
Is the crop going to be marketed?
D.
follow crop recommendations
10.
Laboratory Activity: Each group of students are given specific
plants and apply growth regulator to plant. Over the next three
weeks, students will record the effects of growth regulators. Students
should recognize some effects on these plants.
A.
leaves are a darker green color
B.
internodes are shorter
C.
reduce leaf and flower size but not flowering time
D.
leaves become thinner but feel thinner
SUMMARY
Plant growth regulators, when used properly, will regulate and control
many different plant growth patterns. Always read and follow all label
directions when using any plant growth regulators.
Evaluation
Quiz of plant growth regulators (type and uses)
Lab activity and records
Course: 01.461 General Horticulture
Revised August 1998
Unit 8, Lesson 1
3
Georgia Agriculture Education Curriculum
8.1.1
GROWTH REGULATOR TABLE
REGULATOR
EFFECT ON PLANT GROWTH
USE ON WHAT PLANTS
auxin
promotes growth through cell
division, phototropism, root
formation, apical domain
apple, pear, citrus (keeps fruit
ripe on trees)
gibberellin (GA)
promotes stem elongation
through cell division; young
developing tissue and seeds
apply to dwarf plants, berries,
celery
cytokinin
promotes cell division, delays
leaf aging, prevents
breakdown of chlorophyll
seeds, fruits, roots
abscission acid
inhibitor of growth; counteracts the effects of auxin and
gibberellins
prevents seed germination
ethylene
important in fruit ripening
process and early petal drop
of flowers
Course: 01.461 General Horticulture
Revised August 1998
Unit 8, Lesson 1
4