By: Teo Spengler
What are teak trees? They are tall, dramatic members of the mint family. The tree’s foliage is red when the leaves first come in but green when they mature. Teak trees produce wood that is known for its durability and beauty. For more teak tree facts and information about teak tree uses, read on.
Few Americans grow teak trees (Tectona grandis), so it is natural to ask: what are teak trees and where do teak trees grow? Teaks are hardwood trees that grow in the south of Asia, usually in monsoon rainforests, including India, Myanmar, Thailand and Indonesia. They can be found growing throughout that region. However, many native teak forests have vanished due to over-logging.
Teak trees can grow to 150 feet (46 m.) tall and live for 100 years. Teak tree leaves are reddish green and rough to the touch. Teak trees shed their leaves in dry season then regrow them when it rains. The tree also bears flowers, very pale blue blossoms arranged in clusters at the branch tips. These flowers produce fruit called drupes.
Ideal teak tree growing conditions include a tropical climate with generous daily sunshine. Teak trees also prefer fertile, well-draining soil. For the teak to propagate, it must have insect pollinators to distribute pollen. Generally, this is done by bees.
The teak is a beautiful tree, but much of its commercial value has been as lumber. Under the scaly brown bark on the trunk of the tree lies the heartwood, a deep, dark gold. It is acclaimed because it can withstand weather conditions and resists decay.
The demand for teak wood is much greater than its supply in nature, so entrepreneurs have established plantations to grow the valuable tree. Its resistance to wood rot and shipworms makes it perfect for building large projects in wet areas, such as bridges, decks and boats.
Teak is also used to make medicine in Asia. Its astringent and diuretic properties help to limit and reduce swelling.
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I am not entirely sure as I am from another corner of the world, but a quick (non-conclusive) websearch, for example here and here, suggests something between 25 and 60 years. Assuming that you want thick trees (= significantly more value), I'd aim for the upper end of this range. Besides, teak is supposed to grow slowly for best quality.
Remember that the currently oh so modern term "sustainability" was coined 300 years ago by Hans Carl v. Carlowitz in Germany with regards to forestry. I'm from the Black Forest myself, where wood was (and to some degree still is) a significant source of income for centuries. If you intend to plant trees for your own retirement, I hope that you are a) quite young and b) have a "Plan B". Here in the Black Forest one sells trees that were planted by the grandfather or father and plants trees for the benefit of children and grandchildren.
If you simply happen to own a piece of land and have no better use for it, go for it and plant a few trees, but do it for fun, not for economic reasons. If you can sell a bit of timber in a few decades, it will be a neat little windfall, but don't count on it, there simply are too many things that may go wrong.
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Teak, (genus Tectona grandis), large deciduous tree of the family Verbenaceae, or its wood, one of the most valuable timbers. Teak has been widely used in India for more than 2,000 years. The name teak is from the Malayalam word tēkka.
The tree has a straight but often buttressed stem (i.e., thickened at the base), a spreading crown, and four-sided branchlets with large quadrangular pith. The leaves are opposite or sometimes whorled in young specimens, about 0.5 metre (1.5 feet) long and 23 cm (9 inches) wide. In shape they resemble those of the tobacco plant, but their substance is hard and the surface rough. The branches terminate in many small white flowers in large, erect, cross-branched panicles. The fruit is a drupe (fleshy, with a stony seed) 1.7 cm (two-thirds of an inch) in diameter. The bark of the stem is about 1.3 cm (half an inch) thick, gray or brownish gray, the sapwood white the unseasoned heartwood has a pleasant and strong aromatic fragrance and a beautiful golden yellow colour, which on seasoning darkens into brown, mottled with darker streaks. The timber retains its aromatic fragrance to a great age.
Native to India, Myanmar ( Burma), and Thailand, the tree grows as far north as about the 25th parallel in most of this area but to the 32nd parallel in the Punjab. The tree is not found near the coast the most valuable forests are on low hills up to about 900 metres (3,000 feet). Stands are also found in the Philippines and in Java and elsewhere in the Malay Archipelago. Teak is also planted in Africa, Central America, and South America.
During the dry season the tree is leafless in hot localities the leaves fall in January, but in moist places the tree remains green until March. At the end of the dry season, when the first monsoon rains fall, the new foliage emerges. Although the tree flowers freely, few seeds are produced because many of the flowers are sterile. The forest fires of the dry season, which in India usually occur in March and April after the seeds have ripened and have partly fallen, impede the spread of the tree by self-sown seed. In Burmese plantations, teak trees on good soil have attained an average height of 18 metres (59 feet) in 15 years, with a girth, breast high, of 0.5 metre (1.5 feet). In the natural forests of Myanmar and India, teak timber with a girth of about 2 metres (6.5 feet) and a diameter of 0.6 metre (2 feet) is never less than 100 and often more than 200 years old. Mature trees are usually not more than 46 metres (150 feet) high.
Teak timber is valued in warm countries principally for its extraordinary durability. In India and Myanmar, beams of the wood in good preservation are often found in buildings many centuries old, and teak beams have lasted in palaces and temples more than 1,000 years. The timber is practically imperishable under cover.
Teakwood is used for shipbuilding, fine furniture, door and window frames, wharves, bridges, cooling-tower louvres, flooring, paneling, railway cars, and venetian blinds. An important property of teak is its extremely good dimensional stability. It is strong, of medium weight, and of average hardness. Termites eat the sapwood but rarely attack the heartwood it is not, however, completely resistant to marine borers.
Myanmar produces most of the world’s supply, with Indonesia, India, and Thailand ranking next in production. Since the mid-1980s, numerous countries have restricted teak logging to control deforestation.
This article was most recently revised and updated by Amy Tikkanen, Corrections Manager.
You have asked about teak plantations.Its very fine investment.We will definitely help you in this regard.Here i want to suggest tissue culture saplings.its growth is very fast than seedlings/stump plantations.You will get will get assured income of Rs 10000/- per tree on completion of 10 years.
For more details please contact us
priya Nursery garden,
Teak is indeed a very profitable venture. But bear in mind teak is a very long term crop varying from 22 to 30 years.
The fruit of your efforts will be realized only after the given time frame. Until then you will have to wait and make constant investments in you land in order to get high quality trees.
only if you are able to sustain the growth of trees for the above time frame you should consider tweak.
Other wise go in for tree variety's such an Casuarina, bamboo , eucalyptus , Magnum etc.
Teak tree plantations is lenthy span of cultivation.this was known by everybody.Mr.VKV stated short term tree plants like eugaliptus,caursina and mangium.Is it mangium tree is shot term tree plantations? I dnt have any ieda?Mr Kiriti will throw some light in this regard.i think mr Vkv dnt know the tissue culture technology.The teak now propagted through tissuce culture.And also its gives good yield in short period i.e minmum 10 years.
Priya Nursery Garden,
Teak is profitable in long-term without any doubt.
I have not herd from any Farmer who claimed good yield in 10 years even in commercial cultivators of Panama or Costa Rica.
If any formers claims they are getting good yield in 10 years with TC Plants, It will be great.
In Large scale Commercial cultivation it works in following way. Number of tress to be thinned and interval of thinning will be based on growth and your affordability
First Thinning 200 plants (after 4 years) - No significant income
Second Thinning 200 Plants (after 8 years )- You can earn little money by selling Poles.
Third Thinning 200 Plants ( after 12 years- You can get decent income
You can decide one more thinng at 16 or 20 and the Final cut based on heartwood and sap wood ratio in tree.
Plant 600 Plants/year and do inter crop with no thinning for first 12 years.
I have planted Teak in 30 acres near Mysore and planning to go for Pineapple and or Papaya after teak plants are established.
all the members are of the opinion that teak is good in long term. No body is perfect in science because knowledge generation is a continuous process and one has to learn time and again. Mr ShivKumar , you are advocating for TC teak and frequently mentioning that it can attain good growth in 10 yrs. Thats true but simply saying this does not work in this forum. can you explain why it does better than seed or cutting planted saplings. People writing in this forum are suppose to be more more knowledgeable than a common farmers. A scientific explanation regarding superiority of TC saplings over other one can be more convincing and beneficial to the members.
It is very easy to testify the claim by considering Height and diameter of the Tree.
Please ask for the Sample of a Sliced 10 year TC Teak tree and verify the following
1) Annual rings -Every tree will have circular rings for each year with this with this you can confirm Tree was cut after 10 years or more
2) Heartwood and Sapwood ration- Tree should have substantial heart wood compare to Sap wood. Heart wood fetches real price. Heartwood will be dark in color compare to Sapwood. Sapwood can barely fetch few buck
After validating you can calculate return per tree by Multiplying Volume of Heartwood X Market price of Teak.
As per my knowledge It is taking more than 20 years in current technology for Teak tree to attain considerable yield of Heartwood.
Amarillo tree (Terminalia amazonia) growing in the mixed species plantation at Agua Salud. Credit: Jorge Alemán, STRI
Native to India, teak is the go-to species for reforestation in Central America. But teak often underperforms in the nutrient poor soils that dominate tropical landscapes. To discover if the timber value of teak plantations grown on poor soils can be increased, scientists at the Smithsonian Tropical Research Institute interplanted rosewood and amarillo, both economically valuable native tree species.
Native trees are well-adapted to local environmental conditions, resisting diseases and insect pests. Rosewood (Cocobolo, Dalbergia retusa) is typically sold to instrument makers and craftspeople for a higher price than teak is sold for. Rosewood trees also improve the soil by pulling nitrogen gas out of the air and converting it into fertilizer for itself and neighboring trees. Despite its timber value, rosewood is rarely cultivated and is more often poached from protected areas.
Although amarillo (Terminalia amazonia) is highly valued in Panama as a hardwood tree that grows fast and straight in conventional planting conditions—even in full sun—it has never been formally tested in mixtures with teak and rosewood.
Previous studies predicted that other tree species might not grow among teak trees because teak needs so much water and the roots produce chemicals that may impede the growth of other plants.
As part of the Smithsonian's 700-hectare Agua Salud Project, the largest reforestation experiment of its kind, researchers planted 30 hectares of teak in 2008. Evaluations in 2013 and 2016 confirmed that teak did not do well in Central Panama's nutrient-poor, clay soils.
To improve the profitability and environmental services of the plantation, scientists planted rosewood and amarillo seedlings among the teak trees in 2015. Although researchers added a handful of organic matter and a handful of NPK fertilizer to each seedling as it was planted, far less time and labor was involved than in the establishment of the teak plantation. They measured the seedlings in 2016 and again in 2017.Teak (Tectona grandis) plantation at the Agua Salud Project. Credit: Jorge Alemán, STRI
Virtually all of the rosewood seedlings survived across the site, despite several El Niño events that made this the driest period on record since 1925. Rosewood seedings seem to outperform amarillo seedlings initially, but the trees are predicted to catch up and surpass rosewood as time goes by, based on previous experiments.
"Amarillo will end up being bigger in stature than rosewood, but because of its incredible monetary value, the smaller rosewood will far surpass amarillo in terms of financial returns," said Katherine Sinacore, a post-doctoral fellow working on this species at STRI. "The idea that smaller is better, or in this instance massively more valuable, can be counterintuitive."
Along with the potential to better protect jaguars, migratory birds and other animals by increasing diversity at this continental crossroads, interplanting is also likely to improve water management, critical for the operation of the Panama Canal because both flooding and drought threaten canal infrastructure and transport of goods. While teak grown alone may not increase the "sponge effect," the ability of soils to absorb more water during storms and release it during dry periods, interplanting teak with native tree species may increase this valuable ecosystem service.
"Forestry research is often a waiting game," said Jefferson Hall, STRI staff scientist and director of the Agua Salud project. "Because it takes a long time for trees to grow, researchers plant trees and then wait many years to get results. We were delighted to find that rosewood and amarillo are growing and surviving just as well here at two years as they did in open-grown plantations."
In the future, researchers also will set up experiments to better understand how underground factors such as nutrient and water availability contribute to the success of interplanting with native trees.
"Exotic species like teak dominate timber plantations throughout Panama and the tropics worldwide," said Abigail Marshall, first author and graduate student at the University of Montana. "Our hope is that the early success of rosewood and amarillo interplanted in the Agua Salud Project's teak plantation will contribute to growing evidence for a strategy to increase the use of native tree species in the region and more broadly."
Money doesn’t grow on trees – especially pension money and teak trees. Teak plantations, eucalyptus plantations and truffle tree farms are traditional pension “investments” of the scammers. One key example of such a pension investment scam was in May 2014 when the Pensions Regulator (tPR) banned the following scammers from being pension trustees for one year:
Brian Kensington, Christopher Kensington, BPK & Associates Limited, Sanjay Gambhir, Kanwaljit Gambhir, William Donald-Adkin and Oliver Pyle.
The pension schemes they had been running (listed below) were placed into the hands of independent trustees – http://www.itslimited.co.uk/.
St George Structured Assets Limited Pension Scheme
Wicker Shine Limited Pension Scheme
Halfords Assets Limited Pension Scheme
Bardwell Heights Limited Pension Scheme
Five Rings Limited Pension Scheme
Beausale Limited Pension Scheme
Berkeley Securities Limited Pension Scheme
How did the Schemes work?
These pension schemes were basically set up as a vehicle to make a few individuals a lot of money.
The schemes were set up between November 2011 and February 2013 – they each had a sponsoring employer with the same name, set up in the same time frame as the pension scheme. Not at all suspicious?
The schemes were all registered with the Pensions Regulator by an individual at one company – this individual was neither a trustee nor an administrator of any of the schemes. In tPR’s Compulsory Review, this individual and the company are only referred to as AXXXX SXXXXXX of MXXXXXXX HXXXXXXX (AS of MH)– it would be incredibly handy to know more details of this individual to see if they are behind any more pension or investment scams.
The “MH” company was registered at the same address as BPK & Associates, who were the trustees of the schemes. The director and 100% shareholder of BPK was Anthony Kensington he and Christopher Kensington were the sole signatories for the bank accounts linked to the schemes.
A total of £13.93million of victims’ pensions were invested in the schemes. The monies accumulated in the bank account until they reached £1 or 2 million, and they were then transferred into a single undiversified, unregulated, high-risk investment – completely inappropriate for a pension investment. This investment was a teak plantation – set up by our anonymous friend AS of MH. The only investments into the teak plantation came from these fraudulently-run pension schemes.
The majority of the funds were “invested in the teak plantation, and most of the remainder went in fees to – guess who – the handily-set-up company MH. Some of these fees were paid to “introducers”, who, in an all too familiar scenario, approached members of the public offering them ways to ‘unlock’ their pensions – promising tax-free lump sums, and unrealistically high rates of return on their investments.
Just when you thought it couldn’t get any worse – in November and December of 2013, the teak plantation account was closed, and the funds were transferred to a number of different companies, all with links to our friend MH. According to tPR this meant that the funds “had ultimately been paid to destinations which did not appear to be onward investments but included payments to individuals and commission payments and legal and marketing fees. The Regulator argued that there had been a deliberate and careful “layering” of the funds to allow for the gradual dissipation of the starting fund to a number of further destination accounts.”
Some of the fees went directly to pay off individuals’ mortgages and pay school fees, or in one case to buy a Ferrari.
So what now?
Of the nearly £14 million initially invested, only £4.73 million was left in the bank when HSBC froze the account. The pension schemes are now in the hands of Independent Trustee Services Ltd. Individual victims are facing massive tax bills from HMRC for the amounts taken out of their pensions. They have no idea whether there will be any money left in their pension pots.
The trustees were given a terrifying slap on the wrists and a one-year ban from acting as pension trustees.
As far as we know our anonymous ‘AS’ of MH faced no prosecution whatsoever.
The question remains, if – as tPR’s Lesley Titcomb claims – scammers are criminals, where are the prison sentences?
Forest Resources Department, Chiang Mai University, Thailand
Teak plantations have been widely established throughout the tropics to produce high quality timber in trees of good growth and stem form. Many factors affect the success of teak planting programmes including site, seed supply and seed quality, management and other biological factors such as insects. Site is the primary factor influencing plantation growth and development. Growth and yield of plantations grown in different site qualities, within and outside the teak region is illustrated. With correct site selection, growth and yield can be improved more than 100 %. The composition of suitable teak sites is reviewed. Seed supply is a factor limiting planting scale and the quality of the plantation, especially so in countries where teak is an exotic. Seed requirement in various plantation options is tabulated and the effect of seed sources (provenances) and improved seed on growth and quality of plantations is demonstrated. A short term programme for improved seed and clonal stock production is proposed. Silvicultural management of teak plantation practices in weeding, thinning and insect and fire protection for growth and quality improvement is reviewed.
Teak ( Tectona grandis ) is one of the most well known timbers of the world. Its timber qualities include attractiveness in colour and grain, durability, lightness with strength, ease of seasoning without splitting and cracking, ease of working and carving, resistance to termite, fungus, and weathering, etc. The species is native to the Indian-Burmese floristic region and found naturally in India, Myanmar, Thailand and Lao (Kaosa-ard, 1983) it is an old introduction to Indonesia (Kaosa-ard, 1981). Due to its high timber qualities, market demand, ease of domestication and cultivation, teak plantations have been widely established throughout the tropics from the 1850s (FAO, 1956, 1957). Teak has been successfully established as an exotic in many countries, e.g. Sri Lanka, Bangladesh and China in Asia Ghana, Nigeria, Ivory Coast, Senegal, Togo and Benin in West Africa Sudan and Tanzania in East Africa Trinidad, Puerto Rico and Panama in Central America Brazil and Ecuador in South America (FAO, 1957 Keogh, 1994 Hougs, unpublished data). The global teak plantation area recorded in 1990 was about 1.6 million ha (Hougs, unpublished data) which comprises 75 % of the high grade tropical hardwood plantations (Keogh, 1994). The main objective is to produce high quality timber trees with good growth.
Although teak has been ranked as a high priority species in many countries, its planting programme is still limited to a small or medium scale in many countries. Keogh (1994) notes the proportion of teak to overall plantation in the tropics fell sharply from 11 % in 1980 to 5 % in 1990. This is so especially where teak is grown as an exotic species. There are many factors limiting the success of teak plantation establishment. The three main factors are site quality, quality and quantity of planting materials, and silvicultural management.
Site effects - growth of plantations
The main objective of teak plantation establishment is to produce high quality timber in trees with good or acceptable growth rates. To achieve these objectives, the planting site must be suitable for the growth and development of teak. Teak plantations have been established throughout the tropics, within and outside its natural distribution range. This covers a wide range of climatic conditions, i.e. from the equatorial type to the sub-tropical type with a range of rainfall and temperature of 500-3,500 mm and 2°-48°C (minimum and maximum range) respectively (Kaosa-ard, 1981). Soil conditions also vary from infertile acidic to fertile alluvial. A large variation in growth and other tree characters such as stem form, mode of branching, flowering habit and wood quality of the plantation commonly results. The mean annual volume increment (MAI) of teak plantations over a wide range of plantation conditions varies from 2 m 3 /ha/year to >15 m 3 /ha/year at the half rotation age of 30-40 years (FAO, 1956 White, 1991 Keogh, 1994). Keogh (1994) recommended that the MAI of teak plantation should be not less than 8m 3 /ha/year in commercial planting operations. The site for teak planting should be carefully selected, e.g. through species (site matching. Within a planting zone, the effect of site quality on plantation growth may be demonstrated through the construction of Site Index curves. Data presented in Table 1 show the difference in diameter growth of teak plantations grown in different site qualities, both within and outside teak's natural distribution range. Through site selection, it is shown in the case of Indonesia that the growth of the plantation can be improved to over 116 %.
Table 1. Growth (dbh) of teak plantations grown under poor and good site qualities in selected countries
Sources: #1 Tewari (1992) #2 Chanpaisaeng (1993) #3 Dupuy (1990) #4 modified from Maddugoda (1993)
Site effect - wood quality
It is common knowledge among loggers that teak from wetter site conditions, e.g. along river banks or in the lower moist teak forest, is usually darker in wood colour than that from drier site conditions. Teak wood colour seems to be influenced by the site. As the golden brown wood colour is one of teak's most attractive timber qualities, the variation in wood colour and texture has been widely studied (Sono and Saensakul, 1959 Sandermann and Simatupang, 1966 Sunyata et al ., 1992 Kaosa-ard, 1993). A study on clonal variation in wood colour and texture in Thailand in a 20-year old clonal test clearly demonstrated that teak wood colour and texture is strongly controlled by the planting site (Kaosa-ard, unpublished data). In this test, clones of trees from different locations with different wood colours (i.e. dark brown, golden brown, light brown colours, and wood textures, i.e. stony-wood and waxy-wood textures (produced similar wood colour and texture when planted on the same site ( THE TEAK SITE DEFINED
It is shown that the planting site has a strong effect on the growth, development and wood quality of teak plantations. The productivity of a plantation can be largely improved through the selection of a correct site for the plantation programme. It is noted that the teak distribution pattern in its natural range is of discontinuous or patchy type (Troup, 1921 FAO, 1956,1958). Size, quality, density, and the form of teak trees varies from one location to another. There are several factors which control the distribution and growth pattern of the species. The major factors include the amount and distribution of rainfall and moisture, soil and light.
Teak grows naturally over a wide range of climatic condition, from the very dry (500 mm/year) to the very moist (up to 5,000 mm/year) (Seth and Khan, 1958 Kaosa-ard, 1981). Under very dry conditions, the tree is usually stunted and shrubby. Under very moist conditions, the tree is large and fluted and usually behaves like a semi-evergreen species the wood quality is poor in terms of colour, texture and density. For the production of high quality wood with optimum growth, moisture conditions (as expressed by annual rainfall) should be between 1,200 and 2,500 mm with a marked dry season of 3-5 months (Kaosa-ard, 1981 Keogh, 1987). The dry season refers to a period in which the cumulative rainfall is less than 50 mm per month (Keogh, 1987).
Teak grows best on deep, well-drained alluvial soils derived from limestone, schist, gneiss, shale (and some volcanic rocks, such as basalt. Conversely, the species performs very poorly, in terms of growth and stem form, on dry sandy soil, shallow soil (hard pan soil or lower water table soil), acidic soil (pH Light
Teak has been classified as a pioneer species. Hence, it requires a high light intensity for its growth and development (Troup, 1921 Kermode, 1957 Kadambi, 1972 Kitinanda, 1969 Kwoboshi, 1974). A study conducted by Kwoboshi (1974) clearly demonstrated the effect of light intensity on the growth and development of teak seedlings dry matter production of teak seedlings decreases sharply with a decrease in light intensity. In his study, the dry matter production of seedlings grown under low light intensity of 25% (for 8 months) was 0.6 gm as compared with 14.6 gm of seedlings grown under high light intensity of 75% of full daylight. The optimum light intensity for seedling growth and development is between 75-90% (Kwoboshi, 1974).
Apart from rainfall and moisture, soil and light intensity, other factors such as temperature and elevation also play important roles in limiting the distribution and growth pattern of the species. It is known that teak grows well under warm and humid conditions. A series of studies in controlled environments indicated that the optimum temperature for growth and development of the species is 27-36°C (Gyi, 1972 Kanchanaburangura, 1976 Kaosa-ard, 1977). This range of temperature is quite normal within teak tropical range. Teak poorly tolerates cold and frost conditions during the winter period. Under frost conditions, seedlings and saplings are severely damaged and die (Kaosa-ard, 1981), one reason why the species cannot grow at elevations over 700 metres.
Seed supply is one of the most critical factors limiting the teak planting programmes. This is especially so in countries where teak is grown as an exotic species and seed used is totally from old trials or pilot plantations. Problems of seed supply, including the amount and quality of the annual seed requirement, are considered.
It is well known that teak germination is poor and sporadic as a result of its dormancy behaviour. Under nursery conditions the germination of untreated seed is about 30-50% over a germination period of 50 days (Anon., 1956 Gartner, 1956 Suangtho, 1980 Kaosa-ard, 1986 Kumaravelu, 1993 Phengduang, 1993). This germination behaviour causes a very low plant percentage in nursery production. Wellendorf and Kaosa-ard (1988) estimated that the plant percentage in a teak nursery is only 5%, or five plantable seedlings produced from 100 seeds sown in one crop year. This rate is commonly obtained in large-scale nursery operations (4-5 million seedlings per year), where seed pre-sowing treatment is not practical for the large quantity of seed. The low plant percentage in nursery production is due primarily to poor seed germination behaviour and the growth competition of the non transplanted seedlings in the nursery beds (Kaosa-ard, 1986). The amount of seed required for a hectare of plantation with 4 (4 metre spacing is about 8 kg, including 25% for beating up (Wellendorf and Kaosa-ard, 1988). Estimation of seed requirement for various options in a teak planting programme is given in Table 2. This is based on the fact in Thailand that 1 kg consists of 1,800 seeds 1 litre contains 450 seeds and the plant percentage is 5% (Kaosa-ard 1986 Wellendorf and Kaosa-ard, 1988).
Table 2 shows that the requirement varies from 8 to 34 kg/ha per plantation. Similar estimates of seed requirement are reported from India, i.e., 2.5-43 kg/ha (Sirimathi and Emmanuel, 1986). Such large amounts of seed required per hectare of plantation can be reduced through improvement of seed germination (i.e., seed pre-sowing treatment) and nursery techniques (sowing density, sowing, thinning and transplanting techniques, containerised seedling techniques, etc).
Table 2. Annual stumps and seed requirement per 1,000 ha, plus 25 % for beating up
Source: Modified from Wellendorf and Kaosa-ard (1988)
The success of planting programmes depends not only on the site quality but also on the genetic quality of the planting materials. Although the growth and yield of the plantation can be largely improved through site selection, stem quality (i.e., straightness, persistence of stem axis, branching, flowering, etc.) is strongly controlled by genetic make-up (Keiding et al ., 1986 Wellendorf and Kaosa-ard, 1988 Kaosa-ard, 1993). The results of international teak provenance trials have clearly demonstrated the effect of provenance or seed source on growth, stem quality, early flowering habit and health performance (Keiding et al ., 1986). Through correct selection of provenance or seed source, growth and stem quality can be improved (from the provenance means) as high as 23% and 17% respectively (Keiding et al ., 1986). In many cases, the local provenances performed only as well as, or even poorer, than the exotic provenances. The use of improved seed (i.e., from seed production areas, seed orchards and plus trees) is most essential in the improvement of growth, stem quality and other characters of the plantation. It has been estimated that by using such improved seed, the growth and/or volume production gain of the plantation is increased (from base populations) by 5-25%, depending on types of seed source and planting site (Wellendorf and Kaosa-ard, 1988).
The use of improved seed or plant materials is shown to be essential to increase the growth and quality of plantations. To obtain such improvements, Seed production areas and/or seed orchards are required.
A Seed Production Area (SPA) is a converted plantation or a natural stand for seed production, treated by removing all inferior trees, and SPAs seem the most practical short term option for improved seed production programmes. An abundance of improved seed can be obtained within one year of establishment. Through the SPA option, the gain in volume production of plantations is 5-15% over routine seed sources (Wellendorf and Kaosa-ard, 1986 Kaosa-ard, 1993).
The Clonal Seed Orchard (CSO) is another option of seed source establishment. It is a plantation of mixed clones derived from plus trees, designed, established and managed for seed production purposes. It is established as a propagation part of the improvement programme. Generally, the CSO starts producing seed at 10-15 years and its initial gain is about 25% over the base population (Wellendorf and Kaosa-ard, 1986 Kaosa-ard, 1993).
Seed production capacity of both SPAs and CSOs is relatively poor, at least in the case of Thailand. The production capacity in the SPA and CSO is about 10 and 70 kg/ha of teak seed respectively (Kaosa-ard, 1979 Meekaew, 1992). Low production capacity of teak seed in the CSO is also reported from India, 0.5-1 kg per tree or approximately 50-100 kg/ha (Tewari, 1992). However, a contrasting result is reported from Nigeria, where the productivity of the CSO is as high as 734 kg/ha (Egenti, 1981). The needed areas of SPAs and CSOs to support a 1,000 ha annual planting programme has been estimated and given in Table 3. This estimation is based on available information from Thailand where the seed production capacity in SPAs and CSOs is 10 and 70 kg/respectively.
Table 3. Estimated areas of SPA and CSO for various options of a 1,000 ha planting programme
Source: Modified from Wellendorf and Kaosa-ard (1988)
Apart from SPA and CSO, tissue culture is another option for mass supplying of genetically improved materials for the planting programme of this species. This technique of propagation has been developed successfully for commercial propagation of selected plus trees (Kaosa-ard et al ., 1987 Kaosa-ard and Apavatjarut, 1988, 1989). In this technique, shootlets are produced under laboratory condition and are then transferred to glasshouse conditions for rooting. The rooted shootlets or plantlets are transplanted for stock production. Through this process, the cost of shootlet production (as estimated in 1989) was US$5.12 per 100 shoots at 1 million scale of production (Kaosa-ard, 1990). This production cost seems to be the same level as the cost of seed production (viable seed) in the CSO (Kaosa-ard, 1990). This CSO production cost includes establishment and maintenance of CSO for at least 10 years prior to full seed production, plus the cost of seed collection and processing.
Apart from site and seed problems, the success of teak plantation establishment also depends largely on silvicultural management. The common management includes spacing, weeding, fire protection, insect and disease protection and thinning.
Initial spacing of teak plantation varies (1.8×1.8 to 4×4 m) depending on many factors as site quality, cost of establishment, thinning regime, small wood utilization, planting system, e.g. agro-forestry, intercropping etc. However, site quality seems to be the priority factor directing the size of spacing in the teak planting programme. Results of 12-year-old spacing trials (2×2, 3×3, 4×4, 6×6 m) in Thailand clearly demonstrated the effects of initial spacing on growth, stem quality and weed control in teak plantations of different site conditions. Under dry site conditions, where the initial growth rate of the plantation is poor (e.g. Planting time
Planting time has marked effect on survival and growth in teak plantations, especially when stump planting is practised (Kaosa-ard, 1977). A series of studies on stump storage and planting time in Thailand demonstrated that survival and growth in the early established plantations decreased sharply from May planting through June planting to July planting (Kaosa-ard, 1977). The most suitable planting time for teak is soon after the arrival of the monsoon showers or in the beginning of the rainy season. Phenological development studies showed the importance of planting time, especially on growth (Kaosa-ard, 1982). Teak has only one growth flush period throughout the year (Kaosa-ard, 1982). Shoot growth, as expressed in percentage of annual growth, starts soon after the first rain shower (late April), reaches its peak in the beginning of the rainy season (May-June), thereafter declines sharply in the middle of rainy season (July-October) and ceases during the dry season (November-April) (Kaosa-ard, 1982). Kaosa-ard (1982) also recommended that teak be planted just prior to, or during the growth flush period, i.e. between late April and early June, depending largely on the arrival of the first monsoon rain.
Teak is a light demanding species and its growth and development is reduced sharply under poor light conditions. Hence, intensive weeding is very necessary during early establishment of the plantation, i.e. 1-3 years.
The first thinning is conducted at 5-10 years after planting, depending on site quality and the size of initial spacing. Generally, under good site and close spacing (1.8×1.8 m and 2×2 m) the first and second thinning (mechanical thinnings) are conducted at 5 and 10 years respectively. About 25% of the trees are left for further growth and development after the second thinning. In the Caribbean and Central American region, the first and second thinnings (mechanical thinnings) are conducted when the plantation height is 8 and 16 m respectively (Koegh, 1987). Times and methods of subsequent thinning however vary depending on site and economic considerations. Construction of Site Index tables in relation to stand density at different stand ages is a guideline for setting a thinning regime for each planting site.
Insect damage is a serious problem in teak plantations. This is especially so where the intensive forest farming system is practised, e.g. in well-irrigated plantations. The most common insects which cause severe damage plantations are defoliators and stem borers.
Defoliator insects cause severe defoliation and, hence, reduce growth rate, apical dominance and the seed production capacity of plantations, seed production areas and seed orchards. The most important defoliators causing severe damage in teak plantations throughout the tropics are Hyblaea puera Cramer (Hyblaeidae) and Eutectona machaeralis Walker (Pyralidae) (Chaiglom, 1963 Tewari, 1992). Outbreaks of these insects may occur 2 or 3 times during the growing season (Chaiglom, 1963). After outbreaks, especially of Hyblaea puera, the plantation growth rate may be reduced by as much as 75% (Chaiglom, 1963). Control of outbreaks of these insects requires application of both chemical and biological agents, e.g. Bacillus thuringiensis or BT agents.
Stem borers cause severe damage in young plantations (1-5 years old) damaged trees may die back or top break causing a reduction in growth rate and stem quality. The most important stem borer in young teak plantations is the red or coffee borer Z euzera coffeae Nietner (Cossidae). In Thailand this insect causes severe damage in private plantations where the planting sites were previously sugar cane and tapioca fields. In old plantations, i.e., over 10 years, the beehole borer Xyleutes ceramicus is the most important stem borer. It causes severe damage to the standing trees and also reduces the value of timber, with a close relationship between site quality and the degree of damage caused by the beehole borer (Choldumrongkul, 1989). Plantations established on good site quality have higher degrees of damage than those on poor site quality (Choldumrongkul, 1989). At present, there is no practical chemical and biological method for controlling outbreaks of the beehole borer. Silvicultural treatments such as weeding, control burning, thinning, and intercropping may be the only methods which can reduce the insect populations.
Teak plantations have been widely established throughout the tropics with the main objectives to produce high quality timber within a period of 40-80 years. In general, the productivity of the teak plantation is 8-10 m 3 /ha/year. Three main factors affect growth and quality of the plantation: site quality, seed supply and silvicultural management.
Site quality has direct effect on the growth and development of the plantation. The rotation age can be greatly reduced through site selection. Teak grows well on moist sites. To produce high quality timber trees, the site should be subjected to a dry period of 3-5 months duration. Teak soil is deep, well- drained, and alluvial with high calcium, organic matter and other element content. The soil pH is 6.5-7.5. Teak is a light-demanding species. As a result, intensive weeding in 1-5 year-old plantations is very important.
The supply of improved seed for planting programmes is a major problem especially in countries where teak is an exotic. A large quantity of improved seed can be obtained through establishment and management of Seed Production Areas and Seed Orchards. Clonal propagation by tissue culture is an option for mass production of planting stock. This technique is technically and economically feasible.
Appropriate and timely silvicultural management must be carried out to improve both the growth rate and quality. Initial spacing has marked effects on growth, quality and establishment cost. In poor site quality areas plantations should be established with close spacing. Planting time also plays an important role on initial growth and survival of the plantation. The most suitable time for teak planting is during the growth flush period, i.e., the beginning of rainy season. Intensive weeding should be carried out during the first five years after establishment. The outbreak of defoliators and stem borers has become a serious problem there is no practical method for controlling these insects. First and second thinnings are conducted at ages 5 and 10 years in close spaced plantations using a simple mechanical thinning technique. Subsequent thinnings are carried out using relevant Site Index and Stand Density Tables as thinning guidelines.
Anon, 1956. India In "Country Reports on Teak Forestry" FAO, Rome 21-48 pp.
Anon, 1993. Teak in Indonesia. In "Teak In Asia" Technical Document GCP/RAS/I34/ASB, FORSPA Publication 4, FAO-RAPA 35-40 pp.
Banik, R.L. 1993. Teak in Bangladesh. In "Teak In Asia" Technical Document GCP/RAS/I34/ASB, FORSPA Publication 4, FAO-RAPA 1-10 pp.
Barnes, R.D. 1984. A multiple population breeding strategy for Zimbabwe. In. "Provenance and Genetic Improvement Strategies in Tropical Forest Trees". Edited by R.D. Barnes and G.L. Gibson, 619 - 632 pp.
Boonkird, S. 1964. Progress report on the first teak tree-show in Thailand. Nat. His. Bull. Siam. Soc. 20: 243-256
Brockelman, W.Y. and Baimai,V. 1993. Conservation of biodiversity and protected area anagement in Thailand. Proc. of Skill Transfer Workshop conducted by MIDAS Agronomic Co. Ltd., for World Bank/GEF/Pre-investment Study on Conservation Area Protection, Management and Development Project, Bangkok.
Bryndum, K. and Hedegart, T. 1969. Pollination of teak ( Tectona grandis Linn. f.). Silv. Genet.18:77-80 pp.
Cameron, A.L. 1966. Genetic improvement of teak in New Guinea. Aust. For. 30:76-87 pp.
Choldumrongkul, S. and C. Hutacharern 1986. The relationship between the flower development of teak and its associated insects. Jour. Nat. Res. Coun. of Thailand 18: 54-52 pp.
Egenti, L.C. 1981. Aspect of pollination ecology of teak ( Tectona grandis Linn. f.) in Nigeria: Pollinators and fruit production. In "Proceedings of the Symposium on Flowering Physiology" XVII IUFRO World Congress, Kyoto, Japan. 27-30 pp.
Egenti, L.C. 1981a. Aspect of pollination ecology of teak ( Tectona grandis Linn. f.) in Nigeria. Flowering and insect dynamics. In "Proceedings of the Symposium on Flowering Physiology" XVII IUFRO World Congress, Kyoto, Japan. 17-20 pp.
Egenti, L.C. 1981b. Aspect of pollination ecology of teak ( Tectona grandis Linn. f.) in Nigeria. Viability of reproductive units. In "Proceedings of the Symposium on Flowering Physiology" XVII IUFRO World Congress, Kyoto, Japan. 21-26 pp.
FAO, 1957. Report on teak growing under exotic conditions. FAO/TSC-57/3, FAO Rome.
Gartner, I.C. 1956. Indonesia In Country Reports on Teak forestry FAO, Rome 49-105 pp.
Gram, K. and S.C. Larsen, 1958. The flowering of teak ( Tectona grandis Linn. f.) in aspect of tree breeding. Nat. His. Bull. Siam. Soc. 19: 1-6 pp.
Gyi, K. K. 1972. An Investigation of Factors relevant to Development of Teak Plantation in South East Asia with Particular Reference to Burma. M.Sc. Thesis, Australian National University, Canberra Australia.
Gyi, K.K 1993. Teak in Myanmar. In "Teak In Asia" Technical Document GCP/RAS/I34/ASB, FORSPA Publication 4, FAO-RAPA 51-62 pp.
Harahap, R.N. and I. Soerinegara, 1977. Heritability of some characters in teak. In Proc. "The Third World Consultation on Forest Tree Breeding" Vol 2: IUFRO/CSIRO, Canberra.
Hardiyanto, E.B., Sunyoto, O.H. Soeseno and M. Naiem 1992. Early performance of teak ( Tectona grandis Linn.f.). In "One Century of Sustainable Forest Management with Special Reference to Teak in Java" Proc. International Symposium on Sustainable Forest Management, Yogyakarta, Indonesia. 177-180 pp.
Hedegart, T. 1973. Pollination of teak ( Tectona grandis Linn. f.). Silv. Genet. 22 (4)
Hedegart, T. 1974. The Teak Improvement Centre: Ten years after initiation. Vanasarn 32: 342-356 p.
Hedegart, T. 1976. Breeding system, variation and genetic improvement of teak ( Tectona grandis Linn. f.). In "Tropical Trees" Edited by J.Burley and B.T. Styles, Linnean Soc. Symp. Ser. No. 2: 109-123 pp. Academic Press, London
Kanchanaburangura, C. 1976. Teak ( Tectona grandis Linn. f.) Seedlings and Provenance Variation. M.Sc. Thesis, Australian National University, Australia. 216 p.
Kaosa-ard, A. 1977. Physiological Studies on Sprouting of Teak ( Tectona grandis Linn. f.) Planting Stumps. Ph.D. Thesis Australian National University, Canberra Australia 370 p.
Kaosa-ard, A. 1979. Summary results of research on teak seed production. In Teak Seed Centre, Annual Report No. 2.
Kaosa-ard, A. 1981. Teak Its natural distribution and related factors. Nat. His. Bull. Siam. Soc. 29: 55-74.
Kaosa-ard, A. 1986. Teak in ASEAN: A Survey Report. ASEAN CANADA Forest Tree Seed Centre, p.60.
Kaosa-ard, A. 1986. Teak ( Tectona grandis Linn. f.) nursery techniques with special reference to Thailand. DANIDA Forest Seed Centre Seed Leaflet No. 4A 42 p.
Kaosa-ard, A. 1993. Teak international provenance trials I. Growth and stem quality. In Proceedings "50th Year of Huay Tak Teak Plantation: Teak Seminar" 113-129 pp.
Kaosa-ard, A. 1993a. Teak international provenance trials I. Wood production and quality. In Proceedings "50th Year of Huay Tak Teak Plantation: Teak Seminar". 294-312 pp.
Kaosa-ard A., Apavatjrut, P. and Paratasilpin,T. 1987. Teak tissue culture. In Proceedings of His Majesty's Fifth Cycle Commemorative Conference of USAID Science Research 201-206 pp.
Kaosa-ard, A. and P. Apavatjrut 1988. Teak tissue culture: Rooting and transplanting techniques. In Biotechnology Conference, Washington D.C.
Kaosa-ard, A. and Apavatjrut, P. 1989. Teak ( Tectona grandis Linn. f.) tissue culture. In Regional Symposium on Recent Research Development in Tree Plantation for Humid and Subhumid Tropics of Asia, in Malaysia, June 5-9, 1989.
Kaosa-ard, M. 1990. Teak Tissue Culture: Cost Analysis Report RFD/CMU/PSTC 1990 26 p.
Katasubrato, Y. 1992. The history of sustainable management in Indonesia, the case of teak. In "One Century Sustainable Forest Management with Special Reference to Teak in Java" 3-39 pp.
Keiding, H. 1966. Aim and prospects of teak breeding in Thailand. Nat. His. Bull. Siam. Soc. 21 (1&2).
Keiding H., H. Wellendorf and E.B. Lauridsen 1986. Evaluation of an International Teak Provenance Trials. DANIDA Forest Seed Centre, p.81
Kedharnath, S. and J.D. Matthews, 1962. Improvement of teak by selection and breeding. Ind. For. 88: 277-284.
Kumaravelu,G. 1993. Teak in India. In "Teak In Asia" Technical Document GCP/RAS/I34/ASB, FORSPA Publication 4, FAO-RAPA 27-36 pp.
Loetsch, F. 1958. Report to the Government of Thailand on Forest Inventory of the Northern Teak Bearing Provinces. FAO Report No. 895, Rome.
Meekaew, P. 1992. Genetic Variation in Growth, Seed Production and Foliar Nutrients of Teak. M.Sc. Thesis, Faculty of Forestry, KU, Bangkok, Thailand 73 p.
Namkoong, G., R.D. Barns and J. Burley 1980. A philosophy of breeding strategy for tropical forest trees. Tropical Tree Papers No.16, Univ. Oxford. 67 p.
Namkoong, G. H.C. Kang and J.S. Brouard 1988. Tree Breeding Principles and Strategies. In: Monographs on Theoretical and Applied Genetics 11, Springier-Verlag 180 p.
Nair, K.R. and Mukerji, H.K. 1960. A statistical study of the variability of physical and mechanical properties of teak grown at different localities of India and Burma and the effects of variability on the choice of the sampling plan. Ind. For. Rec. 1:(1)
Nikles, K.G. 1992. Conservation and use of genetic diversity in improvement programmes with industrial forest tree species. In. "Proc. of the Regional Symposium on Recent Advances in Mass Clonal Propagation of Forest Tree for Plantation Programmes" RAS/91/004 Field Document No. 4 83-109 pp.
Person, A. 1971. Observations from a progeny trials of at Longuza. Tanzania Silv. Res. Note, No. 24.
Phengduang, V. 1993. Teak in Laos PDR. In "Teak In Asia" Technical Document GCP/RAS/I34/ASB, FORSPA Publication 4, FAO-RAPA 41-50 pp.
RFD, 1989. Forestry Statistics of Thailand, RFD.
Siripatanadilok, S. 1974. Development of teak flower ( Tectona grandis Linn. f.). For. Res. Bull. No. 31, Fac. Forestry, KU, Thailand 68 p.
Srimathi, R.A. and Emmanuel, C.J.S.K. 1986. Jour. Trop. For. 2: 256-268 .
Suangtho, V. 1980. Factors Controlling teak ( Tectona grandis Linn. f.) Seed Germination and Their Importance to Thailand. M.Sc. Thesis Australian National University, Canberra, Australia.
Suksileung, P. 1975. Clonal variation and inheritance in growth characteristics of teak ( Tectona grandis Linn.f.). M.Sc. Thesis, Fac. For. Kasetsart University, Thailand 45 p.Tewari, D.N. 1992. "A Monograph on Teak ( Tectona grandis Linn. f.)" Int. Nat. Book Dist. Dehra Dun, 479 p.
Wellendorf, H. and Kaosa-ard, A. 1988. Teak Improvement Strategy in Thailand. Forest Tree Improvement No.21, p.43
White, K.J. 1991. Teak. Some aspects of research and development. FAO/RAPA 1991/17.
Forest Resources Department, Chiang Mai University, Thailand
Teak is one of the most valuable timbers in the world. The species is native to South and Southeast Asia but plantations have been established throughout the world's tropics. The major problem in plantation establishment of this species is the supply of genetically improved materials for large scale planting programmes to overcome shortages both short- and long-term improvement and propagation strategies are proposed. The short-term strategy includes the establishment and management of seed production areas, clonal seed orchards and clone banks for seed and clonal stock production. The mass clonal propagation of selected trees, tissue culture in combination with a plantlet cutting technique, is recommended. Long-term improvement strategies involve the development and management of gene resource populations, breeding populations and propagation populations. Genetic structures and functions of these three populations are discussed. In long-term breeding populations, the formulation, establishment and management of single and multiple breeding populations suitable for teak breeding programmes are discussed in detail.
Key words: Tectona grandis , Thailand, seed, seed orchards, breeding, tissue culture, genetics, research.
Teak ( Tectona grandis Linn. f.) is one of the most valuable timber tree species in the world. Its timber quality is recognised as attractiveness in color and texture, suitability for all aspects of household construction, ease of working and carving, resistance to termites, fungi and weathering etc. The species is a member of the Indo-Burmese floristic type and occurs naturally in India, Myanmar, Thailand, and Lao (Kaosa-ard, 1983). In Indonesia, the species is a long established introduction to Java (about 700 years) and neighboring islands, such as Muna, Bawean, Lombok, etc., and thereafter wildly distributed throughout the area (Kaosa-ard, 1983, 1986). The species in Indonesia has become a natural source which is isolated from the continental mainland. Due to its high timber quality and value, plantations of this species have been widely established from the early 1800s both within and outside its natural region (FAO, 1957). At present (1990), more than 1.6 million ha of teak plantation have been established throughout the tropics (Hougs, unpublished data). However, about 90% of this plantation is in the Asian region, especially in India, Myanmar, Thailand and Indonesia where abundant seed can be obtained for large-scale planting. Outside its natural habitat, although its performance is very impressive in many countries, teak planting programmes are still limited, due mostly to an insufficiency of seed. At present teak seed supply and/or exchange, especially from natural sources, is limited to research purposes. There is no commercial seed dealer within or outside the region, and most of the teak planting agencies or organizations have to rely on their own breeding and seed production programmes. If this problem can be overcome, plantations of this species (especially outside its natural region (will be increasingly promoted. Strategies for short-term propagation and long-term breeding programmes of teak are proposed in order to increase the supply of improved genetic material sufficient for large-scale planting programmes.
As many other forest tree improvement programmes, the main elements in the teak improvement programme are: strategies, tree populations, operation and management, research and development.
Tree improvement strategies involve planning and execution for achieving general objectives, especially of long term breeding, propagation and conservation in the improvement programme. The formulation and development of an improvement strategy requires biological and technological knowledge including: genetic variation and gain, flowering biology, mating system, seed production, clonal propagation, planting techniques etc.
Tree populations in an improvement programme consist of genetic resources, breeding, propagation and wood production. The genetic structures of these four populations are the core elements in the breeding programme. Due to the differences in their objectives, genetic structures, variabilities and long- term utilization, these four populations are usually established and maintained separately. Relationships among these four populations are illustrated in Figure 1.
Figure 1. Over time, genetic material is progressed through the series of populations by a process of selection and mating.
Operations and management in an improvement programme are mostly concerned with the availability of human resources, financial resources, infrastructure and organization, knowledge of the genetic parameters and reproductive biology of the species, information, technologies, etc.
Research and development in an improvement programme is essential to solve certain key problems. Moreover, the development of appropriate technologies will assist and facilitate the breeding activities (e.g. pollen extraction and storage, flowering induction, etc.) and propagation operations (e.g. seed production, cuttings, tissue culture, etc.).
The general objectives in the teak improvement programmes are broadly divided into short- and long-term objectives as follows:
Short-term objectives include:
¨ Increased volume production per unit area of the plantation through the improvement of growth rate (e.g. diameter and height growth).
¨ Improved stem quality of trees in terms of: stem straightness stem - clear bole - or pruning capability persistence of stem axis other desirable characters.
¨ Improved wood qualities , e.g. wood color and density.
¨ Production of genetically improved seed (e.g. through the establishment of seed production areas and seed orchards) and vegetative propagules (e.g. through the establishment of clone banks) sufficient for planting programmes.
Long-term objectives include:
¨ Establishment of long-term breeding populations for greater cumulative genetic gains of improved characters.
¨ Manipulation and maintenance of genetic variabilities of the breeding populations through as many generations as possible.
¨ Securing the supply of improved seed and/or planting materials of greater cumulative gain for planting programmes.
To formulate and develop appropriate strategies for teak improvement, the following knowledge and assumptions are concerned particularly with the amount of seed required, and the method of its production.
It is well known that the germination of teak seed is one of the most critical problems in a planting programme, especially where expensive seed from seed orchards is used. Experience gained from the teak growing region, e.g. India, Bangladesh, Myanmar, Thailand, Lao and Indonesia, indicates that the germination of teak in the nursery is very low (30-50%) and sporadic (with a germination period of 10-50 days after sowing (Anon. 1956 Gartner, 1956 Suangtho, 1980 Kaosa-ard, 1986 Kumaravelu, 1993 Phengduang, 1993). This low and sporadic germination is due to the strong dormancy behavior of teak seed, which causes a low plant percentage in nursery production.
In Thailand, for example, under a large-scale nursery operation (4-5 million seedlings per year), the plant percentage is markedly low, only 5 % (Kaosa-ard, 1986 Wellendorf and Kaosa-ard, 1988) with only 5 plantable seedlings produced from 100 seeds sown in one growing season. Based on this assumption, the amount of seed required for one hectare of plantation (with spacing of 4 (4 m) is about 8 kg including 25 % for beating up (Wellendorf and Kaosa-ard, 1988). In India, the seed requirements per hectare of plantation vary from 2.5 kg in Tamil Nadu, to 30 kg in Andhra Pradesh and to 43 kg in Gujarat (Srimathi and Emmanuel, 1986). This low germination percentage and the sporadic germination of the seed can be improved to a certain degree (at least in small-scale nursery practices) through various seed pre-sowing techniques including soaking the seed in water or in a mixture of cow dung and water, alternate soaking and sun drying, heat treatment, etc. (Gyi, 1972 Suangtho, 1980 Kaosa-ard, 1986 Tewari, 1992). The seed biodata, annual stump plant requirements and annual seed requirements of 1,000 ha of plantation in Thailand in various planting options are shown in Tables 2 and 3.
Table 1. General figures on teak seed biodata (Thailand)