Rooting ability in woody plants influenced by several factors for example genotype, age, position of the cutting on the tree donor, period of collection and the media of culture. Many woody plants pass through a stage in which they do not flower called the juvenile stage before they can mature which varies in different species. The juvenile stage has proved to the be the best time to take cuttings for propagation. Manipulation of stock plant juvenility and light has proved to be a powerful tool in successful propagation on the otherwise difficult to root woody species.
Young and fleshy cuttings as opposed to stalky cuttings from older plants root successfully. For this reason, juvenility is a major influence on rooting of woody plants. In a number of species, juvenile tissue is the only one that can generate adventitious roots. Cuttings from juvenile plants have fewer of the thick lignified sclereids and fibers which make it easies for elongating root primodia while mature tissue contain sclerenchyma fibers that may be a physical barrier to root development. They also contain higher levels of root inhibitors as compared to juvenile ones which process increased levels of root co-factors. An experiment conducted at Ehime university (2003), showed that rooting was slower in cuttings from older trees. Cuttings of trees of one to three years rooted relatively well. Those above three years were slower while those between fifteen to twenty five years did not root even after three months. This experiment shows clearly the influence of juvenility in rooting of woody plants.
To prevent rooting difficulties, a lot of caution should be taken throughout the whole process of propagation. The overall precaution to take is to take cuttings from a healthy plant. This prevents spread of disease to the new plant. Tools and pots used must also be clean to ensure little or no contamination.
Water loss: Care of cuttings to decrease excessive water loss is essential. Plant cuttings should be propagated soon after being taken from the stock plant. In case they are not being used immediately, the cuttings should be dipped in water or be wrapped in moist fabric until they are ready for treatment. Frost resistant species can be put in the refrigerator. Remove a half to two thirds of the leaves as water loss will be increased by presence of leaves. Unused cutting should not be kept for a long time.
Treatments: Before propagating, the cuttings should be treated according to the need of the plant and the desired method. Rhizopon and Hortus IBA water soluble salts rooting products are normally used. IBA tratments have been found to induce root primodia initiation though they do little on their development (Hartmann et al 254).
Notching: This is also known as wounding and it is where a small notch is made at the base of the cutting usually by citing a half to three quarter inch ‘V’ cut.This helps in absorbing the tretments.
Selecting the right media: Caution should always be taken ensuring the right media for rooting cuttings ids used. Well known media include rockwool, pearlite with soil mixes, combination of peat with sand among others. Each requires certain precautions and is suitable for different woody plants. For example, rockwool has no retention properties and therefore levels of concentration of the treatments should be lower (MacDonald 135).
Select the best time: Woody plants are especially sensitive to the timing and there reaches a certain age of donor plant when cuttings may not root. The time of the year is also important since cuttings are likely to root well in certain times of the year. For example azaleas cuttings are best taken during winter or summer.. Keeping notes is important so as to record any key events on the cutting, the origin, the time of the cutting and the wather so as to be able to follow the development of the plant.
To ensure proper root formation, the following are important after the cuttings have been propagated. Avoid a rooting mix that is waterlogged so as to allow the sprouting roots to breathe. If waterlogged the cuttings will rot rather than sprout; Make sure that your cuttings are exposed to light to allow photosynthesis which will give the cutting energy to form new roots. Cuttings root better in a warm rooting mix. Temperatures of about 65 degrees and 75 degrees Fahrenheit are encouraged.
MacDonald, Bruce. Practical woody plant propagation for nursery growers: vol1. Portland, Oregon: Timber press, 1986.
Hartmann H.T, D.E, kester F.T Davis, and R.L Geneve. Plant propagation: Principle practices. 6th ed prentice-hall , New Jersey. 1997
Bhusal Chandra Ram, Miutani Fusao, and Laban Rutto. Effects of the rooting of trifoliate Orange (poncirus trifoliata) stem seedlings. Hojo, Ehime: Ehime University, 2003.