Understanding Plant Growth Regulators. What is a Plant Growth Regulator? Chemicals which affect the...
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Understanding Plant Growth Regulators. What is a Plant Growth Regulator? Chemicals which affect the plant in many complex ways Cell division and differentiation,
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
Slide 3
2 Types of Plant Growth Regulators Natural Made inside the
plant Low concentrations Five groups Auxins, cytokinins, ethylene,
gibberellins and abscisic acid Man-made/Synthetic Applied to plants
to obtain a wide variety of changes Makes the plant better or more
saleable!
Slide 4
Which grapes would you rather eat? The ones on the right were
treated with gibberellic acid to make them larger.
Slide 5
Naturally Made Plant Hormones
Slide 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
Slide 7
3 Effects of Auxin on Plants 1. Auxin causes the tip of the
middle stem to grow at a faster rate This trunk should be a single
stem; however, the terminal bud was removed forcing it to
branch.
Slide 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.
Slide 9
3. Auxins allow a plant to respond to the touch of a person or
other object
Slide 10
Cytokinins Responsible for cell division and differentiation
Produced in the root tips They tend to travel up the stem Effect is
Apical Dominance
Slide 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
Slide 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.
Slide 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
Slide 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.
Slide 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
Slide 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