In the work with cultivated plants human has developed a number of special techniques of artificial vegetative propagation . Cuttings (propagules) ar

Plant reproduction by cuttings and layering [Artificial vegetative propagation, propagules]

In the work with cultivated plants human has developed a number of special techniques of artificial vegetative propagation.

Cuttings (propagules) are cut from the mother plant shoots (stem with leaves, in the axils of which the buds are located). These shoots have the ability to form adventitious roots under nodes. By placing the propagule in appropriate conditions, it achieves an establishment of a new individual. Willows propagate well by cuttings (species of the genus Salix), poplar, currant, and others. During the formation of adventitious roots the latter lay endogenously arising in pericycle, often with the formation of an excrescence in the lower end of the cutting, so-called callus (diagram 129). Reproduction by cuttings can be by winter (leafless) and summer (green) propagules. They can be cut whether from stem or root.

Summer stem cuttings

Summer cuttings are cut from the current year shoots, when the shoots have leaves. Cutting must have 1-2 internodes and the length of 3-4 cm. The cut must be done above the node, as there develop more rudiments of roots. On the surface of the cutoff forms the film, beneath which begins enhanced cell division, whereby forms the thickening (excrescence, callus). Adventitious roots and, often, adventitious buds that further develop in shoots, originate in the callus. Green cuttings usually plant in greenhouses to reduce evaporation as cuttings without roots unable to compensate the water loss through evaporation.

Diagram 129. Propagation by cuttings: 1. Formation of roots at the bottom of the propagule. 2. The formation of callus on the internodes cut of dicotyledonous plants with developed shoots from callus tissue

Winter stem cuttings

Winter cuttings are cut from a one-, two- or three-year shoots. The shoots are cut at their base, after leaf fall. By this time many nutrients stored therein. The length of cuttings should be 20-30 cm. Store cut propagules in the sand until spring. In spring they should be planted in the garden bed. By the end of the vegetation period, in place of closing the medullary rays and the cambium, in the shoots form the beginnings of roots — a group of cells of the secondary meristem. Especially a lot of them form in the lower part of the shoot. Adventitious roots develop in the future from them. Shoots develop from axillary buds.

Root cuttings

In addition to stem cuttings, the plants can be propagated by root cuttings where adventitious buds will appear. Shoots development on root cuttings accelerates due to the fact that the cuttings are put into the ground at an angle. Roses, raspberry and other plants propagate such way. Taken from http://worldofschool.org

Diagram 130. Reproduction of trees by layering

Polarity of cuttings

Cuttings method reveals the phenomenon of polarity — the difference between the tip and the base of morphological plant body. From the upper morphological end of the propagule (closer to the top of the plant before its cut) develop shoots; from the lower morphological end of the propagule (closer to the root of the plant before cutting the propagule) always develop adventitious roots. If the propagule cut into pieces, the morphological nature of the upper and lower ends also sharply appears.

Propagation by layering

If you have poor rooting of cuttings apply another method of reproduction.

For reproduction by layering bend aerial branches and covered them with soil. This stimulates root formation. After rooting of branches, they separate from the mother plant. Grapes, gooseberries, tea and other plant propagate such way. Branches of thick trunks may be “taken away” by placing them in a pot, sawed through the side and covered with soil.

After rooting, cut the branch below the pot (diagram 130).