Exercise 7 & 8

Exercise 7 & 8: Practicing different types of layering

    Exercise: Practicing different types of layering.
    Materials Required: Secateurs, prepared nursery beds, growth hormone, sensitive balance, alcohol, measuring cylinders, small tub, planted mother stool
    The most commercially used methods are mound layering for multiplication of rootstocks and air layering for some tropical fruits.
    Simple Layering:
    • Simple layer consists of bending an intact shoot to the ground to cause adventitious root to form (Fig.7.1). The method can be used to propagate a wide range of plants, indoor or outdoor on wood shrubs that produce numerous suckers.
    • Layering is usually done in the early spring using flexible, dormant, one year-old shoot-branches of the plant that can be bent easily to the ground.
    • These shoots are bent and “pegged down” at a location 15 to 20 cm (6-9 inches) from the tip forming a “U”. Bending, twisting, cutting, or girding at the bottom of the “U” stimulates rooting at that location.
    • The base of the layer is covered, leaving the tip exposed.
    Compound or serpentine layering:
    • It is modification of simple layering in which one year-old branch is alternatively covered and exposed along its length ( Fig. 7.1).
    • The stem is girdled at different points in the underground part. However, the exposed portion of the stem should have at least one bud to develop a new shoot.
    • After rooting, the sections are cut and lined out in the field. In this way many new plants can be made from one branch.
    • It is also an easy plant propagation method to perform but is only suitable for plants producing slender, long and flexible shoots. Muscadine grape is commercially propagated by this method.
    Continuous or trench layering:
    • It is the most common method of propagation in woody plants, which produce long vines and are difficult to propagate by other methods of propagation.
    • Vigorous roots of apple like M-16, and M-25 and walnut can usually be propagated by trench layering. In this method, it is important to establish a permanent row of plants to be propagated.
    • The mother plants are planted at the base of a trench at an angle of 450C in rows spaced 90 cm apart.
    • The long and flexible stems of these plants are pegged down on the ground to form a continuous line of layered plants.
    • The young shoots that arise from these plants are gradually mounded up to a depth of 15-20 cm in autumn, winter or at the end of the growing season, depending on the species to be propagated
    Fig. 7.1 Different types of layering
    Air layering ( Marcottage, Gootee, Pot Layerage):
    • Air layering is an ancient method of layering, originally introduced from China and now commercially used for propagation of a number of tropical and subtropical trees and shrubs including litchi, longan, Persian lime (Citrus aurantifolia) , ficus, croton etc.
    • Air layers are made in the spring or summer on stems of the previous season’s growth. The presence of active leaves on the layered shoot speeds root formation (Fig. 7.1).
    • Layers are prepared by making an upward cut about 5 cm long at or about the centre of the shoot. The shoot is then girdled by removing a ring of bark about 2 cm wide.
    • The upper part of wound is applied with IBA paste made in lanolin.
    • The wound is covered with moist sphagnum moss in a way to provide complete cover to it.
    • Polyethylene film is wrapped around the moss grass in such a way as to leave no opening, which could allow evaporation of moisture from the moss.
    • Pruning to reduce the top in proportion to the roots is usually advisable. The rooted layers may be severed from mother plant and may be planted in the nursery under shade.
    Mound /Stool layering or stooling:
    • The term stooling was first coined by Lynch in 1942. Mound layering is a method where the shoots are cut back to the ground and soil or rooting medium is mounded around them to stimulate roots to develop at their bases.
    • This method is commercially used to propagate apple, pear, quince, currants, gooseberry and other fruit crops. In stooling, the mother plant is headed back to 15 to 20 cm above ground level during dormant season (Fig. 7.1). The new sprouts will arise within 2 months.
    • The sprouts are then girdled near the base and rooting hormones (IBA), made in lanolin paste is applied to the upper portion of the ring, the concentration of IBA depends on species but generally 3000 to 5000 ppm is commonly used.
    • These shoots are left as such for two days for proper absorption of rooting hormone, before they are covered with moist soil. Care should be taken to keep the soil heaps moist all the times. It facilitates rooting in the stools.
    • The roots in shoots may emerge within 30 to 40 days. However, the rooted shoots should be severed from the mother plants only after 60 to 70 days and then planted in the nursery.
    Tip layering:
    • It is the simplest form of layering, which often occurs naturally. It is a natural method of propagation for black berries, raspberries etc.
    • The tip of the shoots is bent to the ground and the rooting takes place near the tip of current season shoot ( Fig. 7.1) . The stem of these plants completes its life in two years.
    • The tips of shoots are buried 5 to 10cm deep in the soil. Rooting in buried shoots takes place within a month.
    • The new plants (layers) may be detached and transplanted in the soil during spring. Currants, gooseberries and rambling roses can also be propagated by tip layering easily.
    • The incisions should be given carefully
    • The earthing-up should be done carefully
    • The detached stools/ layers should be lined out properly for hardening and ensuring saleable growth.

Last modified: Thursday, 20 September 2012, 5:49 AM