Plant Cuttings in Agriculture and Horticulture
Investigating the Practical Applications of Vegetative Propagation
Aug 25, 2009
One of the most widely employed methods of vegetative propagation is the use of cuttings. This technique makes use of vegetative parts that have been removed and rooted in sand or some other suitable material under proper conditions of light, warmth, and moisture. Cuttings are made from stems, roots, and even leaves, but stem cuttings are most widely used.
Stem cuttings are often called slips, especially if they come from non-woody plants. A stem cutting consists of a section of stem 3 to 12 inches or even more in length bearing several nodes (place on a stem where a leaf is or was attached) and lateral buds (growth areas along the side of a stem). When such cuttings are placed in soil, roots grow from the lower end nodes while the uppermost lateral buds grow into shoots.
Plant Hormones Encourage Vegetative Growth
A very large number of plants, woody and herbaceous, are readily propagated by stem cuttings. In 1935, new techniques in plant propagation were made possible by the discovery that rooting of cuttings is stimulated by hormones.
Auxins, obtained from organic sources, and later found to be produced by plants naturally, stimulated the growth of roots when applied to the basal end of the cutting. Subsequently, about thirty chemical compounds were found that would stimulate root production.
Cacti are Easily Propagated
Cacti are among the plants readily propagated by cuttings. A good-sized piece of the plant is removed with a sharp knife, placed in a dry atmosphere for a day or so to permit the cut surface to heal, and then rooted in sand.
Many cacti spread naturally by vegetative reproduction. Some, such as the opuntias, have jointed stems, which are readily detached. When they fall onto the soil, they root easily and grow as independent plants. Some species of cacti are highly dependent upon vegetative reproduction and rarely produce flowers or seed-bearing fruit.
Some Food Plants are Propagated by Stem Cuttings
Prominent among the food plants propagated by portions of the stem are sugar cane, pineapple, and cassava.
The varieties of sugar cane are grown by planting sections of stalk, each bearing one or more nodes and buds. Roots spring from the region just above the nodes, and buds soon grow into shoots above the soil.
The pineapple is propagated in several ways. On the flower stalk, just below the fruit, small shoots (slips) are produced. Other shoots, the suckers, are formed in the axils of the main leaves, close to the ground. Slips and suckers, removed from the plant and inserted into the soil, grow into new plants.
Cassava, a shrubby perennial plant 6 to 7 feet high, has been extensively cultivated for its edible roots in the American tropics since pre-Columbian times. The plant is propagated by cuttings, about a foot long, of the semi-woody aerial stems. These are planted in rows, and the roots are ready for harvesting 9 to 12 months after planting.
Propagation of Subterranean Stems is Important
Subterranean stems, modified in various ways, are probably more important in the vegetative propagation of plants than are aerial stems discussed so far. Buds produced at the nodes of rhizomes (a type of horizontal underground stem) give rise to branches that persist underground or develop into aerial shoots. Cannas, iris, rhubarb, and peony are propagated by cutting rhizomes into pieces, each piece bearing a well-developed bud.
The white potato, for food purposes, is propagated only by vegetative means. The white potato is the enlarged and swollen apex of a stolon (a type of horizontal underground stem). In preparation for planting, the tuber is cut into seed pieces, each piece bearing at least one “eye”.
The central bud of each eye develops into a shoot, which produces adventitious roots. Later, stolons develop from lateral buds located at underground nodes. These stolons expand at the tip into new tubers, or what we recognize as the potato.
Propagation by Corms
The commercial varieties of banana produce no seed and are propagated by the corm and by “suckers” or lateral shoots, which arise from buds on the corm. The “stem” of the banana plant arises from a huge, tuber-like corm as much as a foot in diameter. When a new plantation is started, the corm is cut into pieces called “bits,” each weighing three or four pounds and bearing at least one good eye or bud.
The bits are planted about a foot deep in rows. After a few weeks, a shoot appears above the ground and grows for 7 to 10 months before the flower stalk appears. During this time the base of the shoot enlarges into a corm and accumulates large quantities of starch.
In agriculture and horticulture a number of different methods are used to grow and propagate plants. Vegetative propagation through the use of stem cuttings is one of the important of those methods.
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