Unlike seeds, cuttings are a vegetative or asexual method of plant propagation and may be of two main types: softwood Or Hardwood Cuttings.
Softwood cuttings from succulent herbaceous plant material and are normally taken from the centre
or tip of the plant. Flowers and some of the lower leaves are removed and the lower part of the stem is cut across just below a node or joint. Softwood cuttings are usually inserted to about half their length in a well-aerated compost, preferably sterilised by heating or steaming, so that a sufficient supply of oxygen is available around the base of the cutting from where
roots are formed. Frequent watering and shading are also required during the early stages of rooting, to maintain the cutting in a fresh or turgid condition.
Wet conditions reduce rooting by encouraging the development of fungi and other soil organisms which cause decay, this is an additional reason for ensuring that rooting composts are well drained. Softwood cuttings may be from 5-15 cm in length, depending on the growth habit of the plant being propagated; the tip may be removed, if this is very leafy or soft and liable to wilt.
Hardwood cuttings are taken from matconditions normally referred to as being well-ripened. The mature branches or stems from which this type of cutting is obtained have fewer leaves than softwood cuttings, the lower oncs should be removed and the ones towards the tip may be cut across to reduce water loss. The base of the cutting should be cut across below a node, the top portion may also be removed by cutting the stem across immediately above a node or joint. Hardwood cuttings may be from 15-30 cm in length and should be inserted to about two-thirds of their length in a well-drained medium.
Root cuttings Some crops, such as the breadfruit, are propagated by root cuttings rather than stem cuttings, but this method is rarely used for other West African crops.
Layering With the exception of mangoes and a few ornamental plants, layering is rarely used in West Africa. The stems of plants which are difficult to root from stem cuttings are buried under a mound of soil, after a cut has been made in the portion of the stem which is to be buried. A peg is used to keep the stem in position until roots have formed from the buried portion of stem. The rooted portion of stem is then removed by severing it below the rooted section.
Rooting hormones and mist propagation In recent years, the use of root-promoting chemicals or hormones has increased and many proprietary brands of these are now available. Most of them are mixtures of indolyl acetic, butyric or proper ionic acids and they are usually in powder form. Cuttings which are dipped into these powders, or solutions made from them, are likely to root more rapidly than untreated cuttings.
Since most cuttings of softwood and some hardwood plants are likely to wilt shortly after they have been inserted in the rooting medium, regular watering is essential to maintain them in a turgid condition.
The use of mist propagation units in West Africa is increasing, particularly for plantation crop propagation, i.e. cocoa and coffee; these can considerably reduce the time taken for cuttings to form roots.
These units basically consist of a series of very fine spray nozzles which can be operated by an electronic switch. This switch comes into operation when water evaporates from a flat layer of plastic material which separates two wire terminals. The finely atomised
spray then operates, covering the cuttings and the terminals of the switch with a thin layer of water, and after a few seconds, the supply is switched off by the presence of a film of water between the terminals. If mist propagation is used together with root-promoting hormones, a rapid rate of production of rooted cuttings can be obtained.
Plantation crops: Crops such as cocoa, coffee, coconut and oil palm also normally transplanted from containers or nursery are beds to the field and the basic operations required are similar to those already outlined for fruit trees.
These often have to be modified, in view of the large quantities and the labour requirements involved, and it is
common practice to excavate planting holes for plantation crops and leave them to weather for some time, either open or roughly filled, so that the soil can become settled before planting begins.