2.1 Flashcards
Propagule
Definition
Any various vegetative part of a plant (eg bud or offshoot) that aid dispersal of the species and from which a new individual may develop.
In applied propagation this term is used specifically for any form of vegetative propagation resulting in a new plant.
Cambium
Main methods of propagation involving cambium
Heel cuttings
Hardwood cuttings
Layering (simple, serpentine and air layering)
Grafting and budding.
Cambium.
Importance in vegetative reproduction
Cambium continually produces cells that differentiate.
Phloem on outside, xylem inside.
Wounded cambium produces undifferentiated cell mass to seal or heal wound.
This cell mass is called CALLUS.
PGH can cause these cells to differentiate into functioning root and shoot tissue.
How callus production is used in vegetative reproduction.
Synthetic auxin hormone rooting powder is used to promote the development of the callus tissue and differentiation.
In grafting and budding the call using process promotes the union and conjunction of vascular tissues of stock and scion.
Node
Vegetative reproduction
At node there is a high concentration of auxin because of the axillary bud.
This area is often used for heel and root cuttings.
At this point new roots often form most easily.
Petiole
Vegetative reproduction
Specific plants are able to root from leaf petiole.
Eg Saintpaulia ionatha
Leaf cuttings do not include axillary bud so atpre only suitable for plants cabable of forming adventurous buds.
Stems
Vegetative reproduction - types using stems
Stem cuttings - softwood, semi ripe, hardwood and heel cuttings.
Stems can also be used for scion wood in grafting and budding techniques.
Plants that generate form stem cuttings must be capable of producing adventurous roots.
Auxin hormone rooting powder is often used.
Leaf
Types of vegetative reproduction using leaf.
With petiole - leaf petiole cuttings.
Leaf blade/lamina cuttings eg. Streptocarpus.
Full leaf cuttings eg Bergonia Rex
Root
Root cuttings
Used in range of plants.
Sections of root taken to overwinter and grow on in the spring.
Roots contain high levels of carbohydrates providing energy to drive new growth.
Axillary bud.
Propagation method
Budding techniques.
Leaf bud cuttings eg Camellia spp.
Large concentrations of auxins are found at the sea buds to facilitate root promotion.
Control of respiration in vegetative reproduction
Rates of respiration will be controlled by providing bottom heat in many forms of cutting which will assist in the use of energy to produce new roots.
It will promote more rapid cell division particularly during the call using process.
Control of light levels in vegetative reproduction
Light levels will need to be controlled to ensure there is enough light to support photosynthesis needed to produce sugars required by the new plant to convert into energy through respiration. Too much light can limit this process so shading may also be necessary.
Shading will also reduce water loss.
Transpiration
Control in vegetative reproduction
Transpiration needs to be reduced by keeping cuttings (especially softwood cuttings) in an area of high humidity.
Shortage of water within the plant tissue leads directly to stress.
Stressed plants cells tend to close down stomata leading to a cut in photosynthesis resulting in a reduction of readily available energy from the sugars synthesized by leafy cuttings.
