Bambusa tulda

Bambusa tulda Roxb.

Fl. Ind. (Carey ed.) 2: 193 (1832).
2n = 72

Origin and geographic distribution
The natural range of B. tulda extends from northern India (including Assam) and Bangladesh to Burma (Myanmar) and Thailand, where it occurs wild and cultivated. Occasionally it has been introduced on a small scale elsewhere (e.g. in Java and in the Philippines). For map click: Map512.TIF. In Bangladesh B. tulda is one of the most important bamboos (vernacular name: metinga).

B. tulda culms are generally used for construction, scaffolding, furniture, boxes, basketry, mats, household utensils, handicrafts and as raw material for paperpulp. The young shoots are edible but taste slightly bitter, therefore they are preferably pickled (e.g. in India and Thailand). In Thailand the handicrafts made of this bamboo, polished with a mixture of Young oil and oleoresin, are famous. In its natural area B. tulda is also often planted as a wind-break around farms and fields.

Production and international trade
In India and Bangladesh B. tulda is one of the major commercially exploited bamboos, but no statistics are available. In northern Thailand it is one of the two most important species producing edible shoots.

The fibre dimensions of the culm are: length 1.45-3.0 mm, diameter 15-20 µm, lumen diameter 5-5.6 µm, wall thickness 3.2-7.5 µm.
The following physical and mechanical properties have been published for culms of B. tulda: at a moisture content of 12% (air dried): density 722 kg/m3, modulus of elasticity 10,070-12,304 N/mm2, modulus of rupture 66.7-87.9 N/mm2, compression strength parallel to grain 68 N/mm2; at a moisture content of 73.6%: density 658 kg/m3, modulus of elasticity 7980 N/mm2, modulus of rupture 51 N/mm2, compression strength parallel to grain 40.7 N/mm2.
The approximate chemical composition of the culm is: holocellulose 64%, pentosans 18%, lignin 25%, ash 2-3%; the solubility in cold water is 2.6%, in hot water 5%, in alcohol-benzene 1.9% and in 1% NaOH 21.8%.

An evergreen or deciduous, tufted, sympodial bamboo. Culm (7-)16-23(-28) m tall, diameter at breast height (5-)10(-19) cm, wall thickness at breast height 1-2.5 cm, glabrous, green to grey-green or streaked with yellow; internodes 40-70 cm long, white-scurfy when young, with white ring below the nodes; nodes not or slightly swollen, lower ones with aerial roots. Branches developing from all nodes, numerous, usually 3 larger ones at each node, at lowest nodes slender, horizontal and almost leafless. Culm sheath 15-25 cm x 15-25 cm, coriaceous, deciduous, often bearing appressed brown hairs on abaxial surface; blade broadly triangular, cuspidate, coriaceous, erect, minutely retrorse-hispid inside; ligule narrow, entire, minutely ciliolate; auricles unequal, continuous with the blade (larger one) or sinuately separated, margins ciliate. Young shoots green with yellow stripes. Leaf blade lanceolate to oblong, 15-25 cm x 2-4 cm, glaucescent and puberulous beneath, glabrous above except for the scabrous veins; sheath striate, glabrous; ligule very small; auricles fringed with long white hairs. Inflorescences variable, borne on leafless branches or on short leafy branches; pseudospikelets in clusters of 2-5, supported by chaffy bracts; spikelet linear-lanceolate, 2.5-7.5 cm long, consisting of 2-4 glumes, 4-6 fertile florets and 1-2 imperfect or male terminal florets. Caryopsis oblongoid, 7.5 mm long, furrowed, hirsute at the apex.

Growth and development
About one month after germination a seedling produces its first stem and at this stage the rhizome also starts to develop. After 9 months 4-5 young culms have been formed. In Bangladesh an observation to investigate culm production and clump expansion has been carried out. The observation started with vegetatively propagated offsets planted in the field when 1 year old. For 20 clumps, the average number of full grown culms was 3 after 1 year increasing to 8.8 after 5 years and decreasing to 2.7 after 10 years. Clump girth increased from 87 cm in the first year to 4.4 m in the fifth and 5.9 m in the tenth year. Culm height increased from 3.5 m in the first year to 12 m in the fifth and 16 m in the tenth year. In Thailand shoot growth starts yearly at the beginning of the rainy season and it takes approximately 1 month to emerge above the ground. Shoot development may attain as much as 70 cm per day. Culms complete their growth within 2-3 months after their emergence as shoots, and their diameter and height do not increase as they become older. Under dry conditions, B. tulda may shed its leaves.
B. tulda normally flowers gregariously for a period of 2 years in a cycle of 25-40 years, and produces viable seed. However, it also often flowers sporadically or in small groups, without an obvious cycle.

Other botanical information
In Bangladesh several forms are distinguished: 'tulda bans' is the normal form; 'jowa bans' is a large form with longer and thicker culms, mainly used for scaffolding and construction; and 'basini bans' is a form with a larger cavity in the culms and is mainly used for basketry.

In its natural range B. tulda occurs in mixed deciduous forest in plains, valleys, and along streams, up to 1500 m altitude. In moist areas it often grows together with Cephalostachyum pergracile Munro, in drier parts with Dendrocalamus strictus (Roxb.) Nees.

Propagation and planting
B. tulda can be propagated by seed, rhizome cuttings, culm cuttings and by tissue culture. Under ambient conditions, seed remains viable for about 1 month only; when stored dry (in a desiccator over silica gel) viability can be extended to up to 1.5 years. Seed weight is about 70 g per 1000 seeds. Seed germination is 70% within 8 weeks after sowing. In India excellent plantable seedlings were obtained 18-20 weeks after sowing when the seedlings were fertilized with a mixture of 100 ppm urea and 50 ppm P2O5 in split applications 4, 6, and 8 weeks after germination. In Bangladesh, seedlings at 2-4 leaf stage are often collected from the forest floor, potted in the nursery and planted out later.
Propagation by rhizome cuttings with direct planting in the field is very successful (survival more than 90%) and average height of shoots 2.5 months after planting is 1.35 m. Rhizome parts can best be taken at the beginning of the rainy season from 1-2-year-old culms and planted in pits of 60 cm3 at a spacing of 8 m x 8 m.
Propagation by culm cuttings gives varying results. The survival rate was only 10% in a trial in Bangladesh using culm parts 1-1.5 m long bearing 3-4 nodes with viable buds. In India, promising results were obtained with 1-year-old culm cuttings, each with 2 nodal segments, planted horizontally, 5-10 cm deep. The application of growth-promoting substances (coumarin, NAA or boric acid, 10 or 100 mg/l injected as a 300 ml solution in the internode) had no positive effect whatsoever. Planting in May (dry season) was more successful than in August (rainy season). Good results were obtained with 2-year-old whole culm cuttings: 9 months after planting 4 rooted plants per 3 m culm were available.
Branch cuttings can also be successful, but air and ground layering are not.
Propagation by tissue culture is very promising and is already at nursery stage but is still experimental.
In Bangladesh B. tulda is successfully propagated by dividing 9-month-old seedlings into 3 parts, each bearing roots, old and young rhizome, shoots and rhizome buds.

Clumps of B. tulda grown for household purposes need no special attention. New plantings need watering in prolonged dry periods, to ensure establishment. Application of animal manure stimulates growth and culm production. Culms of 3 or more years old should be removed and the number of shoots should be checked to promote proper growth and development of new culms. After B. tulda in natural forests has flowered, it is recommended not to disturb the development of seedlings (e.g. by weeding, protection from grazing and cutting operations).

Diseases and pests
B. tulda has no serious diseases or pests. It is slightly to moderately susceptible to bamboo blight (Sarocladium oryzae) which attacks young bamboos during or soon after elongation growth, usually followed by secondary insect infestation which aggravates the damage. Drenching the soil of affected clumps with a fungicide (e.g. dithane M45) before the rains start improves the survival rates of new culms. Shoot borers (e.g. Dinoderus spp., Lyctus africanus, Stromatium barbatum) can cause considerable losses in cut culms. Treating the culms with 1% lindane or 3% boric acid/borax mixture (1 : 2) can give complete protection, but safer protection methods still have to be developed.

Young shoots to be used as a vegetable should preferably be harvested while they are still underground. In plantations, selective felling of older culms may start 5-7 years after planting. Normally 3-4-year-old culms are harvested, retaining at least 3-6 evenly spaced culms per clump. A 4-year felling cycle is often adopted.

In India (Assam) the annual yield of dry culms of B. tulda is about 3 t/ha. From a selection of 28 superior full-grown B. tulda clumps in India (Arunachal Pradesh) the following data were reported per clump (averages of a 4-year period): number of matured culms 256, culms cut 75, new culms 36; height of culms 20 m, thickness 2 cm, girth 25 cm, length of internodes 43 cm.

Handling after harvest
Traditionally, B. tulda culms are submerged for 10-20 days in running water to improve resistance to powder-post beetles. Subsequently the culms are air dried for 1.5-3.5 months. Culms of B. tulda suffer considerably from cracking and collapse. Cracks often extend along the entire length of the internodes and the culm collapses at these cracks. To improve their durability, culms can be treated with solutions of sodium carbonate, calcium hydroxide or copper sulphate.

Genetic resources and breeding
Germplasm collections of B. tulda are available in India at Arunachal Pradesh (Chessa, Namsai, and in the Centre bamboorium). Representative collections from all areas of its natural distribution are necessary. Breeding programmes have been started on a small scale in India, especially by selecting superior B. tulda clumps. Much more research is needed, however.

B. tulda is a valuable multipurpose bamboo which is hardly used outside its natural range. More research is needed to determine its potential outside this area. To protect natural stands, management and cultivation techniques have to be improved.

P.C.M. Jansen and S. Duriyaprapan

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