1. Understanding Plant Growth Regulators

2. What is a Plant Growth Regulator?
Chemicals which affect the plant in many complex ways
Cell division and differentiation, root and shoot growth, flowering and ripening

3. 2 Types of Plant Growth Regulators
Man-made/Synthetic
Natural
Applied to plants to obtain a wide variety of changes
Makes the plant better or more saleable!
Made inside the plant
Low concentrations
Five groups
Auxins, cytokinins, ethylene, gibberellins and abscisic acid

4. Which grapes would you rather eat?
The ones on the right were treated with gibberellic acid to make them larger.

5. Naturally Made Plant Hormones

6. Auxins Produced by the tip, or apical meristem
Stem cells elongate and divide
They also flow down from the tip of the stem, preventing lateral buds blooming early

7. 3 Effects of Auxin on Plants
This trunk should be a single stem; however, the terminal bud was removed forcing it to branch.
1. Auxin causes the tip of the middle stem to grow at a faster rate

8. 2. Auxins are responsible for allowing a plant stem to grow toward the sun
The left side of the plant was exposed to the sun. The right side had shade and grew faster.

9. 3. Auxins allow a plant to respond to the touch of a person or other object

10. Cytokinins Effect is Apical Dominance
Responsible for cell division and differentiation
Produced in the root tips
They tend to travel up the stem
Effect is Apical Dominance

11. Ethylene This is a gas that affects the plant like a hormone
It is produced in ripening fruit and dying plant material
It stimulates flowering in some plants and causes other fruits and flowers to ripen more quickly and evenly

12. Effects of Ethylene
Ripen fruits faster in a paper bag, than on the counter
On cut flowers & foliage will die
In this experiment, two holly twigs were placed under separate jars for a week. At the same time, an apple was placed in the second jar. The ethylene given off by the apple caused the holly to lose its leaves and die.

13. Gibberellins Helps promotes growth and stem elongation for trees
Produced in the stems, roots and young leaves
Effects are flowering of plants early and breaking seed dormancy too soon

14. Abscisic Acid (ABS Acid)
Found in dormant seeds and in dying leaves
Effects are inhibiting growth and induced bud dormancy
Helps a plant prepare its buds for winter
The dormant bud on the left has a high concentration of abscisic acid. As spring nears, the acid level drops and the bud begins to develop a new shoot.

15. Synthetic Plant Growth Regulators
Useful for commercial plant crops
They can save money, time, and can lead to a better crop
Help reduce size and make plant look shorter
Root more completely
Help ripen faster

16. Assignment
You and a partner will make up a poem/ song/riddle/ect about natural and synthetic plant growth regulators.
You must have the following:
Auxins, cytokinins, ethylene, ABS acid, and Gibberlines
What they do to the plant
Be creative and appropriate
You will present to the class your poem/song/riddle