Week 3 Flashcards
Vegetative Propagation
An asexual method of plant reproduction that occurs in its leaves, roots
and stem. Can occur through fragmentation and regeneration of specific vegetative parts of plants.
Cutting
A cutting is a plant section, originating from the stem, leaf, or root, which is capable of
developing into a new plant. The cutting is usually placed in warm, moist sand.
E.g., crotons and hibiscus plants
How to grow a cutting
- trim a 4-5 inch stem from the mother plant and cut just below a leaf. Remove all but 2-3 leaves
- Dip the stem’s cut end into rooting hormone
- Fill a small container with a soil-sand mixture
- Add a little water to the container (dampen mixture)
- Insert cutting into the growing medium
- Carefully place the container into a plastic bag
- Seal the bag to retain moisture
- Place the bagged container into bright, indirect light
- Open the bag every other day (for air & prevent mould)
- Move cutting into the soil-filled container after 4-8 weeks
- Harden off newly established plants
- Plant rooted cutting into your garden or sell it
Advantages of using cuttings
- the new plant will be identical to the new parent plant
- avoids difficulties of propagating by seeds
- matures faster and flowers sooner
Grafting
- Grafting is the act of placing a portion of one plant (bud or scion) into or on
a stem, root, or branch of another (stock) in such a way that a union will be formed,
and the partners will continue to grow. - The part of the combination that provides the root is called the stock
- The added piece is called the scion.
- When more than two parts are involved, the middle piece is called the interstock.
- When the scion consists of a single bud, the process is called budding.
- Grafting and budding are the most widely used vegetative propagation methods.
Uses of Grafting
- To produce dwarf trees and shrubs
- To strengthen plants’ resistance to certain diseases
- To retain varietal characteristics
- To adapt varieties to adverse soil or climatic conditions
- To produce multi-fruited or multiflowered plants
- To propagate certain species (such as hybrid roses) that can
be propagated in no other way
Tissue Culture
culturing plant parts in an artificial
medium to regenerate into a new plant
Benefits of Tissue Culture
- It produces good quality mature plants very quickly.
- By using this technique we can produce multiple number of the plants
when there is absence of the seeds or the necessary pollinators
required to produce seeds. - We can produce whole plant from few cells and of modified one in
genetic makeup. - Since the plants in this technique are produced in sterile nutrient
environment, there are less chances of transmission of disease. - This technique allow seeds to germinate that otherwise have very low
chances of germination and further growth.
Tissue Culture Process
- Plant material is sterilized (explant)
- Explants placed on a solid/liquid culture medium and
exposed to nutrients, vitamins and plant hormones - Explants grow and pieces are peeled of and transferred to new media (i.e. they are subcultured)
- Shoots emerge from the growing plant material
- Shoots are sliced off and rooted to produce plantlets
- Mature plantlets are transplanted to potting soil for further growth as normal plants
Callus Culture
An unorganized mass of cells that develops when cells are
wounded.
* When the explant is cultivated on media that promote the
development of undifferentiated cells, a callus is formed.
* The majority of callus cells are formed with the aid of auxins and
cytokinins.
* Using plant growth hormones, callus can multiply continuously or be
directed to develop organs.
Artificial Selection
the process of breeding plants/animals for their
desirable traits by an outside source other than the organism itself or natural selection and is controlled by humans.
E.g., different breeds of domestic dogs and the large ears of maize corn
are products of artificial selection.
AS - selection of desirable traits
In this method a plant with a phenotype of interest is selected and
allowed to grow and self-fertilise or cross fertilise with other plants
of similar phenotype of interest.
* In the F1 generation, the plant expressing the phenotype of
interest is picked out to be used as a parent for the next
generation.
*F1 = Filial 1 (literally “first children”)
AS - cross-breeding between compatiable plants
- In this method two different species of plants are crossed to obtain desirable
traits from both species. Hybrid varieties are developed through crosspollination of genetically compatible trees. - For examples, since peaches, nectarines, plums, apricots, cherries, and
almonds are all from the same family they can be crossed. E.g., plumcots
(cross between plum and apricot).
AS - mixture of selection and crossbreeding
This involves the crossing of two members of different species which possess dominant
alleles for particular genes.
* When the two dominant individuals are crossed, they will produce some offspring that
will show all of the desirable characteristics.
* The offspring with desirable characteristics can be selected breed to produce more
favourable qualities in the offspring.
* E.g., Okra was prone to yellow vein mosaic disease. A new resistant variety of okra was
developed by hybridizing the plant with the hibiscus.
