Cuttage is the process of propagating plants by the use of vegetative parts that, when placed under suitable conditions, will develop into completed plats. It differs from layerage  in that the parts used are detached from the parent plant before they have an opportunity to develops roots. Whit species of pl ants that strike roots readily, cottage is a cheap and convenient mode of  propagation. It is used extensively in the propagation of ornamental plants, including deciduous types, broad-leaved evergreens, and coniferous forms. Some frits, such as grapes and figs have been propagated in this manner since ancient time, and more recently there has been considerable progress in the rooting of other fruit plants, such as the Bruce plum. In the majority of cases, hover, the rooting of fruit-tree species is of more importance in the production of uniform stocks for budding of grafting.

Classes of Cuttings  
Plant parts used in making cuttings fall into four groups, roots, leaves, stems, and modified stems. Theoretically, all plants that have primary mortems Arte capable of being propagated by cutting. All plants cannot profitably be increased by this means, however and only practical experience has made it possible to distinguish between species that can be propagated form cutting and those that cannot.

Root Cuttings
As a rule, plants that naturally produce suckers freely can be propagated easily by root cuttings. Some species of plants that root rarely or not all from stem cutting can be reproduced by this means. Persimmon, pear, pecan, apple, and plum are of this calls. They may be stared by root cuttings, but other methods are considered more economical and are in general use. Sweet potato and horseradish are propagated commercially by root cuttings, and blackberries and raspberries may be propagated successfully by this method. It should be borne in mind, however, that a root cutting will perpetrate the part of the plant from which it was secured. A root taken from below the union of a budded or grafted tree reproduces the    seedling stock of unknown baring quality rater thane the standard top. The technique of making root cuttings varies widely with deferment species. The are customarily made from roots that are not smaller that ⅓ inch in diameter, which are cut in lengths of 2 to inches. They are then planet d out in the open the following spring. By another practice the cuttings are started in early winter in greenhouses or hotbeds and transplanted to the open after they have made top growth and formed new roots, such plants are usually large enough to be transplanted by spring. Root cuttings are also planted directly in the field in the spring, without preliminary treatment.  They many be planted in either a  horizontal or vertical position; it planted vertically, end that was nearest the crown of the  parent plant should be uppermost. New shoots develop from root cuttings from adventitious buds, and new branch roots form attentively in the cambium, eithe3r from the old root part used as a cutting or from the base of now shoots that develop from below ground.
Leaf Cuttings
Many plants with thick or fleshy leaves can be propagated by leaf cuttings. Thin-textured leaves dry up before rooting can take place. Practices vary in the actual preparation and planting of leaf cuttings. In some cases the leaf is detached from the parent plant and planted vertically in suitable medium either the petiole and about one-half of the leaf covered. Adventist roots and shoots both develop at the base, usually from the petiole. This arise normally from  tissue closely associated with the vascular cambium, and also in the primary rays. The lemon is an example of a plant that can be grown from leaf cuttings planted in this manner. By  another practice, the leaf is placed flat on sand in a propagating bed, cut transversely across the center vein, and then covered lightly with sand. Adventives shoots will develop where veins were severed, and adventives roots will develop from the bases of the new shoots. Species of Brypohyllum can be grown from leaf cuttings made in this manner.
Stem Cuttings
These are made from herbaceous plants, such as those frequently grown in greenhouse, and from woody plants may be classed as semi hardwood, or softwood , and hardwood, depending upon the stage of growth of the wood used. 
Herbaceous Cuttings :
These are made mostly of greenhouse plants at hat are herbaceous in type. Cuttings of such material are usually soft, tender, and succulent, they require special attention with reheard to temperature and moisture to prevent wilting. Under favorable conditions they root satisfactorily in a relatively by herbaceous cuttings are geranium, coleus, patina, alternate era, chrysanthemum, tomato, and sweet potato.
Hardwood Cuttings :
These are made from a wide verity of plants, including deciduous types, conifers, and broad-leaved evergreens. Cuttings of deciduous plants are taken during the dormant season. Those of some plants are taken in the fall, packed in moist insulating material, and stored at a temperature of 40 Degree F or less. These cuttings are usually placed in the bed about minded; this, however is not essential to rooting. Instead of the procedure just outlined cuttings of some deciduous plants are taken and planted in late winter, shortly before they would normally resume growth. Deciduous cuttings may be made from 4to 12 inches long, depending on the kind of plant. Usually one-year-old wood is used, but to make the top cut slightly above a node and the lower cut slightly below a node. Various kinds of cuttings show differe3nt responses with regard to the point of origin of roots; but the dessert tissue in the vicinity of the node is thought to be of value in preventing drying out or decay of the wood. Deciduous hardwood cuttings are not highly perishable, but they should be protected at all times to times to prevent them from becoming dry.
Many species of plants may be propagated by hardwood cuttings set directly in the nursery row. Grape, fig, and rose are commonly propagated in this manner. Rooting is determined partly by the type of soil in which they are planted; sandy loam soil that is well derived is preferred. In order to ensure good aeration, cuttings are frequently planted Jon high beds. In a heavy clay soil in Oregon, grape cuttings rooted well when setr in holes made with an iron bar and filled with sand. Hardwood cuttings include also those made from mature wood of conifer. Cuttings of such plants are made 4to6 inches long with foliage removed  from the lower portion of the  stem. As the cuttings form roots, new shoots also form, and this top growth is an indication that the cutting is ready to be moved . The customary procedure is to pot the roared plants an drown them in the pots for one season before moving them to the field. Some of the arborvitaes root within 2or 3 months; junipers frequently require 6 months or even longer. Several broad-leaved evergreen plants are grown from hard-wood cuttings. The cuttings of certain citrus species, for example, are made4 to 7 inches long with five or six nodes, from mature terminal growth. Leavers are removed from the lower part of the stem, but two or more are left at the top .As with other types of cuttings, it is important that cutting material be obtained from healthy, vigorous-growing trees. Orange, grapefruit, lemon, American holly, yaupon, and several species of Ligature are examples of board-leaved evergreens that may be propagated by hardwood cuttings.
Internal or Structural Factors:
Internal or structural factors represent conditions within the cutting, which may influence its ability to form roots and develop in to a plant. Such conditions may be affected by treatment to which the cuttings are subjected some time before they are removed from the plant. These treatment defer from external treatments in that they are designed to induce some change in the chemical composition or structure of the material before its is planted in the cutting bed.
Two general requirement are necessary in the formation and growth of roots on cuttings- the plant must have the capacity to  develop root and top growth, and energy must be the available carbohydrate and nitrogen markedly affect the rooting of cuttings. In California, cuttings on the basis of  there starch content. The freshly cut ends of the cuttings were dipped in a solution of iodine in potassium iodide, and the intensity of the staining in wood outside the medullar rays was used as an indication of the amount of starch present.
Cuttings that showed the deepest stain rotted 62 percent and formed good roots; the intermediate group, 35 per cent with moderate roots, and the low-starch group, 17 pre cent with very poor root systems.
Shoots of stock plants from which cuttings are to be taken are sometimes girdled in order to influence the amount of stored food that the cuttings will contain. The girdle is made at the point on the stem which will be the vase of the cutting. The resulting swelling above the girdle is accompanied by an accumulation of stored food at this point and also naturally occurring axons that move from the top of the plant toward the base. The girdling of the shoot is done during the growing season as soon as length  growth ceases, and the material is then removed for cuttings during the following dormant period. The additional amount of reserve food accumulated at the base of the cutting is of value in promoting root formation; the method however, would be practiced only for plants that are difficult to propagate.
If nitrogen is plentiful, and carbohydrates are low, growth of shoots is stimulated, but rooting is slight. Cuttings from plants that have made normally vigorous growth and hence have a carbohydrate accumulation in excess of inorganic nitrogen are more likely to root properly. 
Age and Maturity of the Tissue
There is a define relationship between the maturity of the tissues of ac cutting and the readiness with which it forms roots. If the cutting is soft and immature, it become weakened more readily from transpiration and more susceptible to decay; and if the tissue is old and mature, a longer period of theme is required for satisfactory rooting. In actual practice propagators learn that  certain stage of maturity, and that other kinds  can be grown best from these representing an entirely deferent stage. Specifically, some plants grow best from semi hardwood cuttings and show differences in the responses  of terminal and sub terminal; others  grow best from basal cuttings with tissue s that are more mature; there are also plants. Which root more readily from heel and mallet cuttings in which second year wood is included. Grape and certain plums grow readily by means of truncheon which consist of wood that is several years old. It has been shown that hardwood grape cutting taken from the middle and basal region of a stem normally better and produce more vinous plants than those from near the terminal; they possess more carbohydrates and less nitrogen than stem tips.
Callusing :
Callus formation at the basal end of the cutting was at one time considered it be a vital factor in the rooting of hardwood cuttings. More recently it has been accepted that it does not play an important part in root formation. Some few cases have been observed where roots originated in the callus tissue, but that is uncommon. Callus formation may be of benefit is cuttings that end of the cutting and preventing decay. Callused cuttings also respond more readily to chemicals used to aid in root formation than those not callused.  
Etiolation  :
Parts of shoots not containing chlorophyll are  said to be etiolated, and this condition is regarded as being favorable to root formation. Some investigators have attributed better  rooting to the formation of an hypodermics, as in roots Etiolated may be produced by wrapping stems with tape or by covering  with soil. The exclusion of light causes chlorophyll to dapperer. In some cases shoots are caused to develop in darkens, by mounding  with soil: chlorophyll never develops. Stems arising from below the ground, as in mound or continuous leverage, are etiolated.


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