Useful Propagation Terms. Propagation The application of specific biological principles and concepts in the multiplication of plants.

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1 Useful Propagation Terms Propagation The application of specific biological principles and concepts in the multiplication of plants. Adventitious Typically describes new organs such as roots that develop in unexpected areas such as stems and leaves. Some species develop natural adventitious roots allowing them to adapt to specific environments and extend into new areas. The ability to initiate adventitious roots is the basis for some propagation techniques. Apical dominance The inhibition of the development of some or all lateral buds by the terminal buds (apex) of a shoot. Asexual or Vegetative Propagation Cloning. The process by which, barring mutations, identical clones are developed from a single plant without passage through the seed cycle (sexual propagation). Budding A form of grafting in which a bud and a small section of bark from one plant are properly connected to another plant. Callus A mass of cells produced by a plant through mitosis in response to damage. Callus formation is a precursor of adventitious root formation in some species. Cambium A layer or layers of tissue that are the source of cells for secondary growth. There are two types: cork and vascular cambium. Clonal Life Cycle The life cycle of the individual plant resulting from propagation. The biological and horticultural characteristics of the clone may vary depending upon the location on the seedling plant from which the propagule was taken. Clone The population of plants generated from a single individual. The resulting plants maintain the same genotype as the parent. Cultivar A cultivated variety of a plant that has been deliberately selected for specific desirable characteristics. It must be clearly distinguishable and when reproduced, must retain its distinguishing characteristics. Dedifferentiation The process by which specialized cells lose their specialized features and revert back to unspecialized cells. Can be brought about by wounding or stimulation by growth hormones. Differentiation The process by which vegetative cells produced in the meristems undergo various changes as they mature in order to become specialized for a given function, e.g. root cells.

2 Gametes Special reproductive cells that develop through meiosis and ultimately fuse with another cell during fertilization. Genetic code The set of rules by which information encoded in genetic material I translated into protein by living cells. Genotype The genetic makeup of a plant. Grafting A method of asexual plant propagation where two pieces of living plant tissue are connected together in such a way (vascular connection is made) that they will unite and develop as one plant. Often used for propagation of trees and shrub. Hardening-off The process of gradually acclimating rooted cuttings from the propagation environment allowing them to become more self-sufficient. Indolebutyric acid (IBA) A synthetic rooting chemical found reliable in stimulating adventitious root production in cuttings. Interphase The "living" phase in the life cycle of a plant in which cells grow, obtain nutrients, and make copies of its DNA in preparation for cell division. Latent root initials (preformed) Adventitious root starts that develop naturally on stems while they are still attached to the parent plant and generally lie dormant until the stems are made into cuttings. Layering A form of rooting cuttings in which adventitious roots are initiated on a stem while it is still attached to the plant. Some systems for layering include: Simple layering An intact, usually a flexible, one-year-old shoot is bent to the ground forming a "U". The base of the "U" is covered with soil and pegged. The tip is exposed. Compound layering Like simple layering except that the branch to be layered is laid horizontally to the ground and numerous shoots develop for rooting rather than one. Air layering A branch is stimulated to produce roots while still attaché to the parent plant by making a cut or removing a ring of bark, just below a bud. The cut is treated with auxin and kept moist by enclosing it in moist sphagnum moss wrapped in plastic film. Leaf cuttings Cuttings made from the leaf blade or leaf blade and petiole. The original leaf does not become a part of the new plant. A limited number of species can be propagated by leaf cuttings. Leaf-bud cuttings Cuttings made from a leaf blade, petiole, and a short piece of the stem with the attached axillary bud.

3 Meiosis A type of cell division which is the basis for sexual reproduction. Meiosis does not produce genetically identical replicas of the parents. This results in the offspring having a combination of DNA from both parents. Meristem A region where growth can take place. The primary growing region of a plant includes shoot tips and root tips. The secondary rowing region includes the vascular and cork cambiums. Mitosis The process by which a cell divides to form two daughter cells, each having a nucleus and containing the same number of chromosomes and the same genetic composition as the mother cell. Mutations Genetic changes that may occur spontaneously or result from exposure to specific environmental factors. Phase Change The phenomenon that describes the shift from vegetative growth to reproductive development of a seedling. There are three phases of development: Juvenile The stage of vegetative growth following germination. No flowering occurs. Transitional The plant is outwardly vegetative but is in transition to the reproductive state. Mature The reproductive stage at which the plant produces flowers. Phenotype The plant's observable characteristics or traits. Plant growth regulators Naturally occurring chemicals that provide growth regulation within the plant as directed by its genetic code. There are five major plant hormones: auxins, cytokinins, gibberellins, ethylene and abscisic acid. Each of which have different functions. Auxin A class of plant growth hormones that have an essential role in coordination of many growth and behavioral processes in the plant life cycle, e.g. apical dominance and initiation of adventitious roots. Indole acetic acid (IAA) is the most widely occurring natural auxin. The most useful synthetic auxins are indole butyric acid (IBA) and naphthalene acetic acid (NAA). Cytokinin One of the most important classes of plant growth substance that are essential for cell division. The interaction of cytokinin and auxin are key in plant propagation. Gibberellin Plant hormones that regulate growth and developmental processes such as stem elongation and germination.

4 Ethylene A naturally occurring gas which can have a profound effect on plant growth, including the ripening of fruits. Abscisic acid One of a class of naturally occurring growth inhibitors involved in the control of dormancy of buds and seeds and plant response to stress. Polarity The quality inherent in plant cells that exhibit different properties in opposite parts, i.e., in cuttings, shoots form at the end nearest the shoot tips of the parent plant and roots at the end nearest the crown. Propagation by cuttings Asexual propagation performed by rooting cuttings from the vegetative portion of the plant such as stems, leaves, leaf-buds or roots. Propagule Any plant material used for the purpose of plant propagation, in asexual propagation, a cutting, leaf, bud or other plant part. Rootstock The lower portion of the graft which develops into the root system of the grafted plant. It may be a seedling, a rooted cutting or a layered plant which has an established, healthy root system. Scion The short piece of detached shoot containing several dormant bud which, when united with the rootstock, comprise the upper portion of the graft. The scion has the properties desired by the propagator. Seedling A young plant developing out of a plant embryo from seed. Shoot New plant growth, may include stems, flowering stems, and leaves. Species The fundamental unit used to designate a populations of plants that can be recognized and which reproduces itself. A true species can usually be propagated and maintained by seed. Stem cuttings Stem cuttings can be divided into groups according to the nature of the wood used: Hardwood Cuttings made of mature, dormant firm wood, prepared during the dormant season usually from wood of the previous season's growth. Semi-hardwood (greenwood) Cuttings made from partially matured wood taken at various times of the year depending on the species. Softwood Cuttings made from succulent, new spring growth of woody plants, keeping leaves attached. The window for taking softwood cuttings ranges from two to eight weeks depending on the species.

5 Herbaceous Cuttings made from succulent, nonwoody plants with leaves attached. Totipotency A principle of plant biology: each living cell has the potential to reproduce an entire organism because it possesses all of the necessary genetic information. Root cuttings Cuttings made from root pieces from young plants in later winter or early spring before new growth starts. Rooting media Propagation media suited to the species, cutting type, season and propagation system and that accomplishes four functions: - Holds the cutting in place - Provides moisture - Permits penetration to and exchange of air at the cutting base - Reduces light penetration to the cutting base Wounding Various methods of causing damage to a cutting in order to improve contact between the cutting and media, stimulate cell division and to improve absorption of auxins. The value of wounding in propagation is speciesdependent. Wound-induced roots Adventitious roots that develop only after the cutting is made and is wounded. The outer injured cells die and a plate forms to protect the surface from pathogens and drying out. Living cells behind the plate and certains cells in the vicinity begin to divide and initiate roots. Zygote The initial cell formed when two gamete cells are joined via sexual reproduction. It is the earliest developmental stage of the embryo.