Download Lesson Plan - Colorado FFA

Colorado Agriscience Curriculum
Section:
Plant Reproduction
Unit 4:
Plant Reproduction
Lesson Number 4:
Asexual Propagation I
Colorado Agricultural Education Standards:
AS 11/12.4 The student will demonstrate an understanding of physiological processes in
agriculturally important plants
HRT 11/12.2 The learner will understand and describe the anatomy of horticulture plants.
Colorado Science Standards:
SCI 1.1
Asking questions and stating hypotheses, using prior scientific knowledge to help
guide their development
SCI 3.1
Students know and understand the characteristics of living things, the diversity of
life, and how living things interact with each other and with the environment.
SCI 3.3.5
Using examples to explain the relationship of structure and function in organisms.
SCI 3.3.6
Describing the pattern and process of reproduction and development in several
organisms.
Student Learning Objectives (Enablers)
As a result of this lesson, the student will …
Objective 1: Understand the types of stem cuttings and how to perform them.
Objective 2: Understand the types of leaf cuttings and how to perform them.
Objective 3: Understand root cuttings and how to perform them.
Time: Instruction time for this lesson: 55 minutes.
Tools, Equipment, and Supplies
Power Point or Colored Overheads
Introduction to Plant and Soils Science and Technology Text (page 60)
Agriscience: Fundamentals and Application Text
Key Terms
Cuttings
Stem Tip Cuttings
Heel Cuttings
Leaf Cutting
Split-vein Cuttings
Fungicide
Stem Section Cuttings
Single-eye Cuttings
Leaf Petiole Cutting
Root Cuttings
Rooting Hormone
Cane Cuttings
Double-eye Cuttings
Leaf Section Cuttings
Interest Approach
Much of the seed stock that is used to produce potatoes is replaced with better cultivars or
varieties over a period of a few years. Farmers who produce “seed potatoes” are constantly
seeking plants that are resistant to diseases and pests. Individual potato plants that are identified
in the field as being superior to other potato plants are often selected as parent stock. From the
plant materials obtained from these plants, many new potato plants are cloned. These valuable
young plants are initially raised in a greenhouse environment, and the supply of “seed potatoes”
is expanded in the field until and adequate supply is available for commercial plantings. The
“seed potatoes” are then cut into pieces for planting. A field of potatoes is a perfect example of
massive cloning efforts that have been advanced to a commercial scale of operation. We will
take the next couple of days to explore the fascinating field of asexual propagation in plants and
how these practices are utilized in the agricultural industry.
Summary of Content and Teaching Strategies
Objective 1. Understand the types of stem cuttings and how to perform them.
Slides 1 – 11
Slide 2: As stated previously, asexual propagation is using the vegetative parts of the plant to
increase the number of plants. Its primary advantages are economy, time, ad plants that are
identical to the parents. The primary methods of asexual propagation are cuttings, layering,
division, grafting, and tissue culture.
Slides 3: Herbaceous and woody plants are often propagated by cuttings. Types of cuttings are
named for the parts of the plant from which they come. There are stem tip cuttings, stem
cuttings, cane cuttings, leaf cuttings, leaf petiole cuttings, and root cuttings. The procedure for
taking cuttings is relatively simple. The equipment needed is a sharp knife or a single-edge razor
blade. Sharp equipment will make the job easier and will reduce injury to the parent plant. To
prevent the possibility of disease spreading, it is best to dip the cutting tool in bleach water made
with one part bleach to nine parts water. The tool can also be dipped in rubbing alcohol.
Slide 4: Show slide four and have the students to a quick drawing to illustrate the anatomy of
the plant. This is needed to give them the proper terminology for the remainder of the lesson.
When performing cuttings the lowers and flower buds should be removed from all cuttings. This
allows the cutting to use its energy and food storage for root formation instead of flower and fruit
development. A rooting hormone containing a fungicide is used to stimulate root development.
A fungicide is a pesticide that helps to prevent disease.
Rooting hormone is a chemical that will react with the newly formed cells and encourage the
plant to develop roots faster. The proper way to use a rooting hormone is to put a small amount
in a separate container and work from that container. This procedure will ensure that the rooting
hormone does not become contaminated with disease organisms. Do not put the unused
hormone back in the original container.
Cuttings are normally placed in a medium consisting of coarse sand, perlite, soil, a mixture of
peat and perlite, or vermiculite. It is best to use the correct medium for a specific plant to obtain
the most efficient production in the shortest possible time. The rooting medium should always
be sterile and well drained, with moisture retention ability to prevent the medium from drying
out. The medium should be moistened before inserting the cuttings. It should then be kept
continuously and evenly moist while the cuttings are forming roots and new shoots.
Stem and leaf cuttings do best in bright, but indirect, light. However, root cuttings are often kept
in the dark until new shoots are formed and start to grow. For most plants, the most popular
method of making cuttings is by stem cuttings. On herbaceous plants, stem cuttings may be
made almost any time of year. However, stem cuttings of many woody plants are normally taken
in the fall or the dormant season or both.
Slide 5: Stem tip cuttings normally include the terminal bud. They are taken from the end of the
stem or branch. A piece of stem between two and four inches long is selected, and the cut is
made just below the node. The lower leaves that would be in contact with the medium are
removed. The stem is dipped in the rooting hormone and is gently tapped to remove excess
rooting hormone. The cutting is then inserted into the rooting medium. The cutting should be
inserted deep enough so the plant material will support itself. It is important that at least one
node be below the surface of the medium because new roots will grow from it.
Slide 6: Stem section cuttings are prepared by selecting a section of the stem located in the
middle or behind the tip cutting. This type of cutting is often used after the tip cuttings are
removed from the plant. The cuttings should be between two and four inches long, and the lower
leaves should be removed. The cutting should be made just above a node on both ends. It is
then handled as a tip cutting. Make sure that the cutting is positioned with the right end up. The
axial buds are always on the tops of the leaves.
Slide 7 - 8: Some plants, such as the dumbcane or bamboo have cane like stems. These stems
are cut into sections that have one or two eyes, or nodes, to make cane cuttings. The ends are
dusted with activated charcoal or a fungicide. It is best to allow the cane to dry in open air for
one to two hours. The cutting is then placed in a horizontal position with half of the cane above
the surface of the medium. The eyes, or nodes, should be facing upward. This type of cutting is
usually potted when the roots and new shoots appear.
Slide 9: Heel cuttings are used with woody-stem plants. A shield-shaped cut is made about
halfway through the wood around the leaf and axial bud. Rooting hormone may be used in the
same manner as in the other types of cuttings. The cutting is inserted horizontally into the
medium.
Slide 10: When the plant has alternate leaves, single-eye cuttings are used. The eye refers to the
node. The stem is cut about a half inch above and below the same node. The cutting may be
dipped in rooting hormone, and then placed either vertically or horizontally into the rooting
medium.
Slide 11: When plants have opposite leaves, double-eye cutting is the preferred type of cutting.
It is often used when the stock material is limited. A single node is selected, and the stem is cut
a half-inch above and below the node with a sharp tool. The cutting should be inserted vertically
in the soil medium.
Objective 2. Understand the types of leaf cuttings and how to perform them.
Slides 12 – 17
Slide 12: For many of the indoor herbaceous plants, a leaf-type cutting will produce plants
quickly and efficiently. This type of cutting will not normally work for woody plants, however.
A cutting made from a leaf with a petiole cut to less than a half inch is referred to as a leaf
cutting. To prepare a leaf cutting, detach the leaf from the plant with a clean cut and dip the leaf
into the rooting hormone. Place the leaf cutting vertically inot the medium. New plants will
form at the base of the leaf and may be removed when they have formed their own roots.
Slide 13: For leaf petiole cuttings, a leaf with a petiole about half to one and half inches long is
detached from the plant. The lower end of the petiole is dipped into the rooting hormone and
then placed in the medium. Several plants will form at the base of the petiole. These plants may
be removed when they have developed their own roots. The cuttings may be left in the medium
to continue to form new plants.
Slides 14 & 15: Fibrous-rooted begonias are frequently propagated using leaf section cuttings.
The begonia leaves are cut into wedges, each containing at least one vein. The sections are then
placed into the medium.
New plants will form at the vein that is in contact with the medium. A section-type leaf cutting
is made with the snake plant. The leaf is cut into sections two to three inches long. It is a good
practice to make the bottom of the cutting on a slant and the top cutting straight. This is done so
you can tell the top from the bottom. The sections are placed in the medium vertically. Roots
will form reasonably soon, and new plants start to appear. These are to be cut off from the
cutting as they develop roots. The original cuttings may be left in the medium for more plants to
develop.
Slides 16 & 17: Split-vein cuttings are often used with large leaf types, such as begonias and
other large leaf plants. With split-vein cuttings, the leaf is removed from the stock plant, and the
veins are slit on the lower surface of the leaf. The cutting is then placed on the rooting medium
with the lower side down. It might be necessary to secure the leaf to make it lie flat on the
surface. A good method is to use small pieces of wire, bending the wire like hairpins and
pushing them through the leaf to hold it in place. The new plants will form at each slit in the
leaf.
Objective 3. Understand root cuttings and how to perform them.
Slides 18 – 19: It is best to use plants that are two to three years old for making root cuttings.
The cuttings should be made in the dormant season when the roots have a large supply of
carbohydrates in reserve. In some species, the root cuttings will develop new shoots, which, in
turn, will develop root systems. In others, the root system will be produced beore new shoots
develop.
If the plant has large roots, the root section should be four to six inches long. To distinguish the
top from the bottom of the root, make the top cutting a straight cut and the bottom one a slanted
cut. This type of cutting should be stored for two to three weeks in moist peat moss or sand at a
temperature of about forty degrees Fahrenheit. When removed from storage area, the cutting is
inserted into the medium in a vertical position. The slanted cut should be down, and the top
straight cut just level with the top of the medium. If the plant typically has small roots, a section
one to two inches long is used. The cutting is placed horizontally a half inch below the surface
of the medium.
Review/Summary
Utilize a Hieroglyphic E-Moment for students to review and organize their notes.
Application
Extended classroom activity:
Acquire different types of plants and develop a lab to demonstrate the different methods of
asexual propagation covered in this lesson.
FFA activity:
Use Life Knowledge Lesson MS 35 to illustrate just as it is important to choose the correct
propagation method for certain types of plants, it is important to choose the appropriate use of
language and humor with certain groups of people.
SAE activity:
Use Life Knowledge Lesson AHS 51 for an upperclassman with a solid SAE program can, like a
plant cutting, help other members get a new SAE started by brainstorming ideas.