Vegetative Propagation

Development of plants from Stem Cuttings

Introduction

• Cuttings can be taken from almost any part of the stock plant (the original plant) to produce new plants that are genetically identical.

• The actual method chosen depends on the species of plant and time of year: – Stem • Softwood • Herbaceous • Semi – hardwood (evergreen) • Deciduous hardwood – Leaf – Roots

Steps in taking Softwood cuttings

• • • • • Softwood cuttings are taken from the tips of shoots which are young and green and where the stem is still soft.

The cutting should be 5 – 10 cm long The lower leaves should be removed to reduce lose of water through transpiration sometimes it is also necessary to reduce the area of larger leaves as well.

The cut end should be dipped into a rooting hormone (Seradix B no.1, containing IBA indole-3 butyric acid) The cutting should then be inserted into a rooting medium and left in a humid environment.

Steps in taking Herbaceous Cuttings

• Succulent, nonwoody plants (Chrysanthemums, Carnations etc.) may be propagated this way • A stem 8 – 13 cm long with or without leaves • The conditions required for sucessful propagation are the same as for softwood cuttings • Bottom Heat (placing the pot on a heating pad to warm the rooting medium up to an optimum 20 – 25 initiated faster.

o C) will stimulate root formation to be

• • • • •

Steps in taking Semihardwood Cuttings

Woody, broadleaved evergreen plants are propagated in this way The stem should be 8 (up to a 1 / 3 – 15 cm long with lower leaves removed of the original surface area) The stem should be removed just below a bud A heel should be left on the cutting to increase the surface area of the cambium cells (growing and dividing cells). This can be done by pulling the stem downwards to rip a little of the bark off the stock plant IBA, high humidity and bottom heat enhance rooting

Steps in taking Deciduous Cuttings

• • • • • • • This method is suitable for deciduous or narrow-leaved evergreen species such as pines) The length of the stem varies depending on the species e.g. 20 cm for black currants to 3 m for poplar poles At least 2 buds (nodes) must be on the stem The material is usually taken from last seasons growth during autumn (pruned branches are often used) The stem may be wounded by removing bark from the just above the basal cutting (at the bottom) to expose more cambium aids root development Dipping in a strong IBA powder such as Seradix 3 is often required The stems should be inserted into the ground outside and do not require any additional heat or increased humidity because they do not have any leaves to lose water from

Summary of Stem Cuttings

Type of cutting Softwood Herbaceous Semi-hardwood Deciduous Description New, soft succulent woody species Season propagated Spring to summer Succulent stems from nonwoody plants Year round Partially mature wood on current season’s growth, wood plants Late spring to late summer Mature, dormant, woody plants Autumn to late winter Length of 8 cutting – 13 cm 8 – 13 cm 8 – 15 cm Up to 3 m Conditions High humidity, bottom heat, rooting hormone (Auxin such as IBA) High humidity, bottom heat IBA, high humidity and bottom heat. Cutting should be “wounded” to have a heel A high concentrated IBA application, planted directly outside

Steps in taking Root Cuttings

• This method is best carried out on young stock plants during winter • It is not a common method but can be used for Wisteria or

Ailanthus

• The polarity (which way is up) is very important when planting vertically. Usually the root cutting is planted horizontally just below the surface of the rooting medium • Bottom heat helps to develop roots and shoots in a few weeks

Leaf Cuttings 1

• • • The laminar (leaf blade) or petiole (stalk) may be used to propagate a few varieties of plants • African violets and begonias are propagated by removing a single leaf (either the whole leaf or part of the blade)

Sansevieria

(“mother-in-laws tongue”) leaves may be sliced into sections

Begonia rex

leaves have their veins cut and laid flat on the growing medium

Leaf Cuttings 2

• As the leaves have no roots, they must be provided with a highly humid environment and bottom heat is recommended • The new plants develop from either the end of the petiole or from the veins of the blade depending on the method used

Physiology of Root and Shoot Formation for Cuttings

• All cuttings go through similar physiological developmental stages from the time of cutting to weaning (when the cutting is removed from the propagation area to an environment similar to which it will be planted).

• Dedifferentiation is the early stage when adventitious roots or buds form from differentiated cells triggered to form new meristematic cells.

The First Stage

Dedifferentiation this is when adventitious roots or buds form from differentiated cells triggered to form new meristematic cells.

This occurs in the cambium cells.

The Second Stage

The formation of root initials from cells near the vascular bundles which have become meristematic by dedifferentiation.

The Third Stage

Parenchyma cells form callus which develops behind the wounded surface of thecutting to protect it from drying out and from pathogens.

The Fourth Stage

Development of the Root Primordia from the root initials.

The Fifth Stage

Growth and emergence of the adventitious roots through the outer tissues and through the callus. Vascular tissue develops between the root primordia and the cutting.

The Sixth Stage

The cutting is removed from the propagating area and hardened off or weaned.