There are tree species which have not been traditionally raised on a commercial scale in Uganda, due to the fact that, the main emphasis for commercial plantations has been on pines and Eucalypts raised from seed. Over the past 15 years, tree growers have expanded their preferences to include eucalyptus clones and species like Gmelina, Melia, Tectona, and more recently bamboo. Therefore, it will increasingly become important to raise in tree nurseries these and other species that might emerge in the foreseeable future.
Grafting and budding are nursery techniques in which two sections from different, but compatible plants (e.g. different mango varieties) are joined together to grow as one plant. The grafted plant has a scion taken from the plant whose characteristics you need, but which does not grow well on its own, and a rootstock of a different plant onto which the scion is fixed to take advantage of the good rooting system.
Budding is a variant form of grafting where the bud of the desired plant is inserted into another plant so that it can grow to produce the desired crop. The grafting operation makes it possible to combine the qualities of both plants, e.g. resistance to a particular disease with characteristics of a good fruit.
Grafting can be done to speed up the period of maturity, or to help in multiplication of a desired variety, which may produce trees of better form, more fruits, tasty fruits, disease resistance plants or dwarf plants which are easy to harvest (Mbora, et al, 2008).
Quoting Maynard, B. K., and N. L. Bassuk. 1990, Texas A & M University (TAMU), Mbora, et al (op cit) has indicated that grafting is among the most expensive propagation techniques, being three times more costly than cuttings and fourteen times more expensive than seedling propagation. Nevertheless, markets continue to require grafted and budded plants for improved plant quality, fruit yield, superior forms, and better adaptation to greater ecological ranges.
Instruction 53: The Guide for Tree Nursery Management [1] (Chapter 6) should be used to guide the operations of grafting and budding in tree nurseries
Instruction 54: Before choosing to use grafting and budding as a prominent method for propagating planting materials in the nursery, the forestry practitioner shall survey the market for such planting materials and adjust the level of production accordingly.
Clones are genetically identical plants which are not reproduced from seed but by some other means such as rooted cuttings or tissue culture (see the difference between clones and genetically modified plants in Box 2). In Uganda, Eucalyptus is commonly cloned, especially for commercial plantations, but other species like Markhamia spp, Ficus spp, Apples, Teak, and Bamboo can also be raised as clones, should the demand arise. Furthermore, hybrid clones combine desirable properties from several different plants and are produced through tree breeding programmes. For Eucalyptus, hybrid clones bring together such properties as fast and uniform growth, high productivity, small crowns, resistance to pests and diseases, and straight stems which lead to a good quality, highly marketable product.
Box 2: Clones versus Genetically Modified Organisms
Clones are essentially cuttings which are rooted to produce a plant of the exact genetic makeup as the mother plant from which the cutting was taken. They are not genetically modified plants, which are produced through introducing new DNA into the genetic makeup of a plant (genetic engineering) to come up with a new genetic constitution (genome) of an organism. To produce a GM plant, new DNA is transferred into plant cells. Usually, the cells are then grown in tissue culture where they develop into plants. The seeds produced by these plants will inherit the new DNA
Source: https://royalsociety.org/topics-policy/projects/gm-plants/what-is-gm-and-how-is-it-done/
Current commercial clonal nursery tree production is based mainly on cuttings taken from a mother plant, placed in a rooting or growing medium, and eventually producing roots and shoots that form a new plant identical to the mother plant. Cloning in forestry offers certain advantages over seed propagation and because of these advantages, many forest plantations are raised through clones. Some of the potential advantages of clones include : [2]
a) They can address challenges of seed sourcing, i.e. it helps avoid frequent seed sourcing, especially if quality seed has to be imported
b) Planting materials can be produced throughout the year
c) Superior genotypes can be maintained, leading to high quality planting stock
d) Uniformity of populations which makes marketing easier
e) Fast growth and so reduction of the period of yield production
f) Conservation of genetic resources can be enhanced
Section 5 of the Guide for Tree Nursery Management [3] provides the procedure used in propagating clones in the nursery.
Instruction 55: The Guide for Tree Nursery Management (Chapter 6) referred to above should be used to guide the operations of producing clones in tree nurseries
Melia volkensii is a multipurpose, fast growing tree species that produces high value timber in rotations of between 10 and18 years, attaining a height of up to 20m and a dbh of 40cm. Other products include poles, posts, fodder, medicine, firewood and bee forage. It tolerates drought conditions and is resistant to termites, and thus it is particularly suited to the drier areas in the Northern and Eastern regions of Uganda, and the cattle corridor in general.
Instruction 56: Section 7 of the Guide for Tree Nursery Management [4] describes the procedure for raising seedlings of Melia volkensii in the nursery. The Guide also makes reference to Kenya Forest Service, 2018, which should be used together with the Nursery Management Guide to raise high quality seedlings.
Tectona grandis (teak) is a highly valuable furniture grade timber species. The timber is also very good for high grade construction and curving purposes. Thus, teak is a high value timber species, even on the global market, and thus a promising broadleaved species for plantation forestry in Uganda. Its value notwithstanding, growing of teak in a plantation environment in Uganda is a recent phenomenon. Therefore, there is limited experience in raising teak planting materials in nurseries. Nevertheless, this experience is increasing as demand for the planting materials is growing. Today teak is widely grown mostly by smallholder entities on privately owned land, especially in Northern Uganda, where the growth conditions are right.
Instruction 57: Teak may be raised from seed, cuttings, or stumps. For details on each method, the procedures laid out in the Guide for Tree Nursery Management should be followed. CIFOR has also prepared a guide for managing smallholder teak plantations which has a detailed section on nursery practices for teak (Pramono, A.A., 2011 [5]). The nursery manager should also refer to this guide as Uganda builds its home-grown practices.
Instruction 58: In view of the relatively young experience in growing commercial teak plantations in Uganda, the nursery manager shall keep a detailed record of the experiences being gained. Such information should include at a minimum the source of the seed, germination percentages, growth rates, success rates for seed, cuttings, and stumps, pre-sowing treatment, and the whole process of raising the planting stock.
There are over 1,600 bamboo species growing in different parts of the world. Of these Uganda has 13 species, two of which are indigenous [6] , and seven of these are edible [7]. However, care must be taken in preparing the bamboo shoots for food as they may contain significant toxic amounts of cyanogenic glycosides. On the other hand the cyanogenic glycocides in bamboo degrade readily in boiling water, and thus boiling bamboo shoots or cooking bamboo shoots should remove the problem [8].
Bamboo (mainly Oxytenanthera abyssinica (lowland) and Oldeania alpina (mountainous) is a monocarpic plant (i.e. it flowers and produces seeds only once in its lifetime), and the length of its flowering cycle ranges from 3-120 years, depending on bamboo species. Additionally, bamboo seeds are short-lived and they lose viability within one to two months, making it difficult to propagate bamboo from seeds. Bamboo seeds vary in size and shape according to the species.
Some seeds are grain-like, similar to rice, while others are like berry, mango, etc. Bamboo grows well in very poor and shallow soil which is unsuitable for many crops. It is very drought resistant, sustains itself with minimal rainfall, and has a very economical water uptake (United Nations Industrial Development Organization, 2009[9]).
Bamboo is used in a wide range of applications, including construction materials, furniture, fencing, handicrafts, pulp and paper, edible shoots, and animal fodder. It can be woven into numerous products including mats, baskets, trays, hats, lampshades, caps, lanterns, etc. However, this requires specialised equipment which is costly, and skills to work the equipment. Nevertheless, manufacture of the products will normally be done by the private sector, who will definitely invest in it as the markets for the products continue growing.
Young bamboo shoots can be cooked and eaten as a vegetable [10], and the foliage can be used as animal feed. Bamboo helps maintain soil fertility by returning nutrients and humidity to the soil in the form of leaf litter. Thus, it is used for ecological purposes such as soil stabilization and erosion prevention on hill slopes. Consequently, Uganda has developed a Bamboo Strategy and Action Plan as a framework for development of bamboo in Uganda, with the following strategic objectives (MWE and INBAR, 2020 Ministry of Water and Environment of Uganda & the International Bamboo and Rattan Organisation (INBAR ) [11]
• Increase production and productivity of bamboo forests in Uganda.
• Increase return on investment in the bamboo industry through processing and value addition.
• Improve knowledge management in the bamboo industry through awareness creation, education and research.
• Improve governance and institutional arrangement in support of the bamboo industry
Bamboo cultivation for commercial purposes is relatively recent in Uganda, although many parts of the country have had bamboo growing naturally for a long time. Therefore, experiences for raising planting materials in the nursery are also in their nascent stages of development. Consequently, the Strategy and Action Plan has recognised the need to produce and supply quality planting material [Specific Objective No. (iv)] through:
• Promoting innovative ways of ensuring the supply of quality bamboo planting materials
• Ensuring that clean and disease-free planting materials are imported into the country
• Ensuring that technologies for production of indigenous and exotic bamboo planting materials are developed and disseminated.
Instruction 59: In addition, MWE has included a section on Propagating Bamboo Planting Materials in the Guide for Tree Nursery Management. This Guide should be used to produce bamboo planting materials. This guide shall be revised at least once every 5 years in order to incorporate lessons learnt in the course of implementing the Strategy and Action Plan.
Other tree species which are emerging as important species on the tree growing scene include White teak (Gmelina arborea), Musizi (Maesopsis eminii), and Nsambya (Markhamia lutea), among others, and additional ones will continue to emerge. Katende, et al, 2000 [12] gives useful guidance on other species which are not commonly being demanded by tree growers.
Instruction 60: FPs shall continuously experiment with promising species in the different ecozones of Uganda, with the aim of producing planting materials of these species in the nursery cost-effectively.
MWE, 2020; Op cit ↩︎
ibid ↩︎
Op cit ↩︎
Op cit ↩︎
Pramono, A.A., Fauzi, M.A., Widyani, M., Heriansyah, I. and Roshetko, J.M. 2011 Managing Smallholder Teak Plantations: Field Guide for Farmers. CIFOR, Bogor, Indonesia ↩︎
Ministry of Water and Environment of Uganda & the International Bamboo and Rattan Organisation (INBAR), 2020. 2019 – 2029 Uganda National Bamboo Strategy and Action Plan ↩︎
Phyllostachys nigra f. henonis, Oxytenanthera abyssinica, Dendrocalamus strictus, Dendrocalamus giganteus, Dendrocalamus asper, Bambusa vulgaris, Bambusa polymorpha ↩︎
United Nations Industrial Development Organization, 2009. Bamboo Cultivation Manual. Guidelines for Cultivating Ethiopian Lowland Bamboo – Eastern Africa Bamboo Project ↩︎
There are over 1,600 bamboo species but only just over 100 are edible. Of these Uganda has 13 ↩︎
Ministry of Water and Environment of Uganda & the International Bamboo and Rattan Organisation (INBAR), 2020. 2019 – 2029 Uganda National Bamboo Strategy and Action Plan ↩︎
A B Katende, Ann Birnie and Bo Tengnas, 2000. Useful Trees and Shrubs of Uganda – Regional Soil Conservation Unit (RSCU) Technical Handbook Series ;10 ↩︎