Dendrocalamus strictus Dendrocalamus strictus (Roxb.) Nees, Linnaea 9: 476. 1834; Munro, Trans. Linn. Soc. London 26: 147. 1868; Gamble, Ann. Roy. Bot. Gard. Calcutta 7: 78. 1896 and Hook. f., Fl. Brit. India 7: 404. 1897; Camus, Les Bambusees 152. 1913; Bennet and Gaur, Thirty Seven Bamboos Growing in India 61. 1990; Tewari, Monogr. Bamboo. 77. 1992. (Fig. 40). Bambusa stricta Roxb. Pl. Corom. 1: 58, t. 80. 1798. VERNACULAR NAMES Bengal - Karali, Gujarat - Nakur bans; Kiri bidiru; Maharashtra - Male bamboo, narvel; Orissa - Salia; Tamilnadu - Kalmungil; Andhra - Sadanapa Veduru; Tripura - Lathi bans; Kerala - Kallumula.
A deciduous densely tufted bamboo. Culms 8-16 m high, 2.5-8 cm diameter, pale blue green when young, dull green or yellow on maturity, much curved above half of its height; nodes somewhat swollen, basal nodes often rooting, lower nodes often with branches; internodes 30-45 cm long, thick-walled. Culm-sheaths variable, lower ones shorter, 8-30 cm long with golden brown stiff hairs on the back, sometimes glabrous in dry localities, striate, rounded at the top, margin hairy; ligule 2-3 mm high, toothed; auricles small, blade triangular, awl-shaped, hairy on both sides. Leaves linear-lanceolate, small in dry localities, up to 25 cm long and 3 cm broad in moist areas, rounded at the base into a short petiole, tip sharply acuminate with twisted point, rough and often hairy above, softly hairy beneath; ligule very short. Inflorescence a large panicle of large dense globular heads 4-5 cm apart; rachis rounded, smooth. Spikelets spinescent, usually hairy, the fertile intermixed with many sterile smaller ones, 7.5-12 mm long and 2.5-5.0 mm broad, with 2 or 3 fertile flowers; empty glumes 2 or more, ovate spinescent, many-nerved; flowering glumes ovate, ending in a sharp spine surrounded by ciliate tufts of hair; palea ovate or obovate, emarginate, lower ones 2-keeled, ciliate on the keels and 2-nerved between them, uppermost not keeled, often nearly glabrous, 6 to 8-nerved. Stamens long-exerted; turbinate, stalked, hairy above and surmounted by a long style ending in a purple feathery stigma. Caryopsis brown, shining, ovoid to sub-globose, ca.7.5 mm long, hairy above, beaked with persistent base of the style, pericarp coriaceous. Different chromosome numbers are reported as 2n=72,70 and 56 hexaploid (Sobita Devi and Sharma, 1993). FLOWERING AND FRUITING Gregarious flowering cycle varies from 25-45 years. This does not mean that all the clumps of a tract flower at the same time. It commences with intensive sporadic flowering for 2-3 years, increasing progressively resulting in the flowering of all the clumps in a period of five years. Sporadic flowering is seen almost every year. Gregarious flowering is related to injury, nutrition, climatic conditions and soil factors. Management practices and biotic interference influences flowering of D. strictus. When proper silvicultural practices are adopted flowering is reported to be delayed by 3-5 years. Flowers appear from November to February and fruits are seen from February to April. Freak flowering of 1-3 year old seedlings in nurseries and natural forests are occasionally reported. Studies have shown that precocious flowering was induced by tissue culture and mutants through gamma irradiation of seeds. Gregarious flowering has been reported from different parts of the country; Kalagarh Forest Division of Uttar Pradesh during 1950-56 and in Kalahandi and Rayagada Division of Orissa State in 1967, Mandal Division of Madhya Pradesh during 1961-63; various localities of Maharashtra during 1940-1942, 1948-49, 1957-1958, 1961-1962, 1978-1980. Blatter (1930) listed the flowering years of this species from various parts of India and adjacent regions for the period 1865-1914. Ahmed (1969), Uppin (1978) and Kadambi (1949) reported that non-production of new culms in the preceding years could be an important event which signifies the approach of flowering in this species, but Banik (1981) observed that all the clumps produced new culms in the preceding years, some in the first year of flowering and no new culm production in the second year of flowering. Studies on floral biology and breeding behaviour showed that the species is dichogamous and protogynous. The gynoecium matures 3 to 4 days before the androecium. Flower opens between 6 to 13 hours and opening depends on atmospheric temperature. The species is anemophilous. The insects feed on pollen but not pollen vectors. Parthenocarpy and apomixis do not occur. Pollen fertility is about 98 per cent (Nadgauda et al., 1993). Fruit is a glans, fusiform with obtuse or aristate rostrum at the apex covered with white pubescence. The length of rostrum varies from 2 to 4 mm. The fruit is covered with three persistent glumes. Surface is smooth with hard seed coat. Average length and width of seed varies from 7 to 7.3 mm and 2.98 to 3.33 mm respectively. Fruit navel and ventral suture are absent and pericarp is crustaceous (Appasamy, 1993). DISTRIBUTION AND ECOLOGY This species occupies 53 per cent of total bamboo area in India. This is one of the predominant species of bamboo in Uttar Pradesh, Madhya Pradesh, Orissa, and Western Ghats. Widely distributed in India in semi dry and dry zone along plains and hilly tracts usually up to an altitude of 1000 m., also commonly cultivated throughout the plains and foot hills. D. strictus is widely adaptable to temperatures as low as -5oC and as high as 45oC. This species is mainly found in drier open deciduous forests in hill slopes, ravines and alluvial plains. It prefers well-drained, poor, coarse, grained and stony soils. It occurs naturally in tracts receiving as low as 750 mm of rainfall and also in extensive gregarious patches or as an understorey in mixed forests and teak plantations. ANATOMY AND FIBRE CHARACTERISTICS Rhizome is pachymorphic type. There are two kinds of buds on the rhizome, the scaly pointed and the flat buds. The scaly pointed buds develop into rhizome and the flat ones develop into culms. Apical dichotomy is observed as a rare phenomenon (Krishnamoorthy, 1978). Three growth types are reported, common type, large type and dwarf type. The first type is common, second type is seen in depressions and third type is found in ridges and hotter places. The culm internode consists of a single layered epidermis followed by a layer of sclerenchymatous hypodermis. Cortex 4-5-layered parenchymatous fibres constitute 40-50 per cent. Across the wall, the fibre length increases from periphery, reaches its maximum at about the middle and decreases towards the inner part. Fibres in the inner zone of culm 20-40 per cent shorter, shorter fibres always near the nodes. With increasing height of the culm a slight reduction in fibre length occurs. Culm macerate shows very thick, thin and very thin-walled fibres, septate fibres present, fibre tips pointed or blunt, wall lamellation of 3-7-layered (Sekar and Balasubramanian - personal communication). In leaf epidermis, stomata common, arranged in two bands, in 1-3 alternate rows, subsidiary cells triangular, surrounded by small, globose papillae. Long cells long and narrow with uniform width, ends almost straight, walls sinuous. Papillae small, scattered. Interstomatal cells short and broad with sinuous walls and deep concave ends; papillae scattered. Short cells mostly solitary, costal and intercostal. Cork cells costal not distinct, intercostal distinct. Silica cells costal, distinct, common, intercostal, frequent. Silica bodies costal nodular, intercostal dumbbell to '8' shaped. Prickles frequent, intercostal, with round base and small pointed apex, base surrounded by a ring of papillae. Microhairs frequent, bicelled, apical cell larger or equal to basal cell, apex tapering. Macrohairs common, long, costal and intercostal, base raised, surrounded by a ring of papillae (Luxmi Chauhan et al., 1988). The average fibre length of D. strictus is 2237祄, diameter 8.2 祄, lumen width 5.1 祄 and wall thickness 6.2 祄, slenderness ratio 272.8, flexibility ratio 62.2, Runkel ratio 1.4. The thick-walled bamboo fibres exhibit a polylamellate structure with alternate broad and narrow lamellae. Its composition is such that narrow lamellae regularly alternate with broad ones. Width of the broad lamellae appears to vary. The microfibrillar arrangement in these two types of lamellae is of crisscross type. The narrow lamellae show a fibrillar angle of 80 to 90o to the cell axis, while in the broad ones the fibrils are almost parallel to the axis (Parameswaran and Liese, 1976). Seed coat is made up of palisade like cells of sclereids in a single row. It is followed by dark stained 4 to 5 layers of crushed cells. The seed coat is covered by a thick cuticle. Two to three layers of aleurone cells occur next to the crushed cells. It is followed by endosperm with reserve foods. The embryo is located at the chalazal end (Appasamy, 1993).
CHEMISTRY Proximate chemical analysis showed cold water solubility 6.6 per cent, hot water solubility 7.6 per cent, 1 per cent NaOH solubility 22 per cent, alcohol benzene solubility 6.9 per cent, holocellulose 70.9 per cent, Klason lignin 27.6 per cent, pentosan 17.1 per cent, ash 4.6 per cent (Maheswari and Satpathy, 1990). The pulping characteristics vary with age, locality and position of culm. Pulping properties of the species show moisture 10 per cent, screened pulp yield 45.2 per cent, total pulp yield 46.8 per cent, kappa No.285, viscosity 30.2 (Cp) at 25oC'lignin in bamboo 26 per cent, lignin in pulp 3 per cent, pentosan in bamboo 23.2 per cent, in pulp 15.3 per cent, pulp yield unscreened 57 per cent, screened 50.9 per cent (Singh et al. 1976). Yield and chemical analysis of holocellulose and hemicellulose is also reported by Rita Dhawan and Singh (1982). Spectral absorbance of cellulose 0.354, lignin 0.296 (Sekar and Balasubramanian - personal communication). The hemicellulose of bamboo is similar to hemicellulose of hardwoods. The sugar composition of hemicellulose consists of xylose, arabinose and glucose. Glucuronic acid is also present in small amounts with xylose as the main constituent. The nodal portion has lower holocellulose content, but pentosan, lignin and ash are higher compared to internodal region (Maheswari and Satpathy,1988). Studies on the effect of pH on prehydrolysis of D. strictus indicate that pulp yield decreases at higher pH. Analysis of seeds showed 73 mg starch, 8 mg total sugars, 1 mg phenol, 4 mg lipid and 14 mg protein per 100 mg of sample (Appasamy, 1993).
SILVICULTURE AND MANAGEMENT Site requirements: Dendrocalamus strictus grows on practically all types of soils provided there is good drainage. It does not grow on water-logged or heavy soils such as pure clay or a mixture of clay and lime. Well-drained localities with sandy loam are the best for bamboo growth. The species is found growing well in the areas having a rainfall between 750 mm-4000 mm and it flourishes in regions where the relative humidity of the air is low. The species is usually not found on precipitous slopes or on flat ground unless it is well-drained. It prefers hilly ground and is resistant to frost and drought. Seed storage: The seeds if not sown
immediately after collection, may be stored in bags. If it is to be sown after one year,
it should be dried and stored in sealed tins. The seeds can be stored for longer duration
by keeping over silica gel or anhydrous calcium chloride in desiccator at 3oC to 5oC after
reducing the moisture content to 8 per cent (Gupta and Sood, 1978). Hydration and
dehydration treatments also reduce loss of viability (Sur et al., 1989). Abnormalities
observed in seeds during storage were such as coagulated ball embryo, concentrated
sporulation of storage fungi, embryo detachment along the epithelial layer, black
encrustation of inner walls, discontinuous black spots, embryoless endosperm, jelly like
embryo fragments, shrunken embryo, shredded endosperm and pitly air space (Karivaratharaju Natural Regeneration: After gregarious or sporadic flowering, under natural conditions, the seeds germinate soon after the first monsoon showers. It is observed that large number of seedlings survive particularly on newly exposed soils. Artificial Regeneration: (1) Seedling: When fruiting occurs seeds are collected by sweeping the ground under the clumps during seed fall. Mature seeds are separated from the chaff by winnowing. Seeds are better collected before the onset of monsoon. One kilogram contains approximately 30,000 seeds. Germination varies from 25 to 61 per cent. A temperature of 30oC and 50 to 70% moisture level in the germinating medium is ideal for germination. Degluming the seeds accelerates germination. A good irrigated nursery with standard sunken beds (12 x 1.25 x 0.3 m) is preferred. The soils in the bed is worked and sterilized by burning the debris and mixed with farmyard manure. Seeds are pretreated for 24-48 hrs in cold water. About 1/2 kg of seeds are sown in a bed in drills 24 cm apart and lightly covered with soil. Germination starts after 7 days and completes in about 17 days. One-year-old seedlings are transplanted in the pits of 30 cm3 at the espacement of 6 m x 6 m. However, it was reported that 2-year-old seedlings give better survival percentage. The roots of the seedlings should not be exposed to sun and care should be taken that the buds on the rhizomes are not injured. (2) Vegetative propagation: Different methods like offset planting, rhizome planting, rooting of culm cuttings and tissue culture are used. One-year-old culms are cut through with a slanting cut about 90 or 120 cm from the ground and the rhizomes to which they are attached are dug up with roots intact and cut off to a length sufficient to include a well- developed bud. Planting is done before the onset of the rainy season. Rhizomes are separated from the mother plant during the onset of monsoon and planted in pits of 45 x 45 cm. Culm cuttings can be used for propagation when seeds are not available. About 40 to 70 per cent of rooting can be obtained in culm cuttings depending on the period of collection, age of culm and treatment with growth regulating substances. Cuttings treated with NAA 100 ppm during February to March gave maximum rooting response (Surendran and Seethalakshmi, 1985). Horizontal planting in the nursery beds was better than the vertical and oblique planting methods. Seasonal variation in rooting response is reported and it is attributed to the variation in nutrient contents in the culm (Gupta and Pattanath, 1976). Observations on fertilizer and spacing trials in the nursery of less than two years, indicated that closer spacing is better and the application of NPK enhance the biomass production by three times (Patil and Patil, 1990). Considerable work has been done on the tissue culture of this species. The various explants used are, node, seed, seedling, shoot, excised embryo and other methods like multiple shoot production, rooting and in vitro flower induction are used, (Zamora, 1994). Growth: The main period of growth of the bamboo is 2-3 months during which time they attain their full height and diameter. The development of lateral branches takes place during the second season of growth. After the first season silicification and hardening of culms take place. Growth is completed about 2 months after the rainy season. There is an initial short period of 14-18 days showing maximum rate of growth (22-33 cm/day) accounting for 25 to 56 per cent followed by moderate growth (11 to 16 cm/day) and subsequently slow growth (9 to 13 cm/day). During the day time, height increment is about 40 per cent as against the night increment of 60 per cent. Maximum growth per day is 37 cm. The months of June-July-August is the season of continuous vegetative activity which indicates that there exist a definite periodicity with regard to growth (Shanmuganathan et al., 1980). Yield: It has been estimated that one hectare may contain a growing stock of 4000 to 5000 culms (250 to 300 clumps) and provide an annual harvest of 750 to 1000 culms on a three year felling cycle. From a plantation having a spacing of 5 x 5 m yield is about 3.5 t/ha/ year. In favorable localities, D. strictus in each clump has 30-50 culms of 15-18 m height and 6-10 cm diameter. Plantation trials from Karnataka reports
annual net income of Rs.35,000/ha/year starting from 6th year onwards (Yellappa Reddy et
al., 1992). Intercropping with Sesbania grandiflora, Leucaena leucocephala, Lotononis
bainesii and Casuarina equisetifolia are reported from Karnataka. Another study
on the yield of D. strictus from a plantation with a spacing Felling cycle suggested is 3 to 5 years. Although a three year felling cycle has been adopted, a cutting cycle of 4 years is preferable since it allows the clumps rest and the rhizomes are not disturbed too frequently. Congestion can occur by cutting the culms from the periphery of the clumps, grazing and extraction by neglecting the cutting rules. This can be avoided by observing the general 'horse shoe'pattern for cutting. Cultural operations like thinning, cleaning, protection from fire and grazing need to be followed (Gupta, 1964). PESTS AND DISEASES Young shoots are susceptible to fungal attack. The green young shoot turns brown and comes off easily when pulled, leaving the area of transformation soft and brown, smelling strongly of molasses. Preventive measure is drenching the clumps with blue copper in advance. Many diseases like, damping off caused by Fusarium spp., leaf spots, leaf blight and leaf rusts caused by species of Alternaria, Colletotrichum, Dactylaria, Dasturella and Helminthosporium, culm rot caused by Fusarium oxysporum, culm-sheath rot by Glomerella cingulata and little leaf disease by Mycoplasma-like organisms are reported from Kerala (Mohanan, 1990). The major spermoplane fungi reported on stored seeds were species of Fusarium, Drechslera, Curvularia, Alternaria, Dactylaria, Aspergillus, Chaetomium and Penicillium (Mohanan, 1990). A rust due to Dasturella bambusina affects bamboo. The other causal agents are white ants and rodents. The application of termiticide and rodenticide will reduce the damage considerably. The major insect pests of D. strictus are Ochrophara montana (affects seeds) Holotrichia consanguinea (affects rhizomes) Hieroglyphus banian (defoliates) termites (damages roots) Estigmene chinensis (culm borer) Cyrtotrachelus dux and C. longimanus (young shoot borers) Myocalandra exarata (green shoot borer) Chelyophora caratitina (young shoots) Olethreutes paragramm (young shoots) Calamochrous pentasaris (defoliator) Crocidophora ptyophora (leaf roller) Messepha absolutalis (defoliator) Pionea flavofimbriata (leaf skeletoniser) Pyrausta bambucivora (leaf roller) Pyrausta coclesalis (defoliator) Dinoderus sp. and Lyctus africanus (shoot borer) (Tewari, 1992). PHYSICAL AND MECHANICAL PROPERTIES Mechanical properties vary according to the age, position of culm and locality. Average properties from ten locations in India are given below. Specific gravity 0.719, moisture content 10.7 per cent, modulus of rupture 118.4 N/mm2, modulus of elasticity 1.59 kN/mm2, crushing strength parallel to grain 64.5 N/mm2 (Sekar and Gulati, 1973). As compared to teak, bamboo has in general higher basic strength. A comparative study with mild steel has shown that the average ultimate tensile strength of Dendrocalamus strictus is nearly equal to the strength of mild steel. The specific ultimate tensile strength of bamboo specimen is nearly six times the specific ultimate tensile strength of mild steel. The notch impact strength of bamboo specimens is only about 15-20 per cent of the impact strength of mild steel. But by taking into account the densities of mild steel and bamboo, the specific impact strength of bamboo specimens is 50 per cent greater and specific impact strength of bamboo specimens soaked in araldite is 100 per cent greater than the specific impact strength of mild steel. Bamboo specimens have poor torsional shear strength in comparison to the torsional shear strength of mild steel. Bamboos have maximum stiffness along the fibres and minimum stiffness transverse to the fibres. The variation of modulus ratio (E/E2) for bamboo specimen is similar to the variation of modulus ratio of fibres reinforced composities. NATURAL DURABILITY AND PRESERVATION Fresh bamboos can be treated by the following methods (1) Steeping (2) Sap displacement (3) Diffusion process (Singh and Tewari, 1981). Dry bamboos can be treated by soaking and hot- cold process. In another study, brush application with the oil type or water soluble type or solvent type of preservatives, particularly of the last kind is recommended. It is found that the untreated bamboo has a service life of 2-5 years. By open tank treatment the service life can be extended to 10-15 years and by pressure process further it can be enhanced to 10-20 years. Untreated bamboo used as posts are destroyed by termites and fungi in about 1 or 2 years. It is reported that bamboo under cover, or used for structural use lasts for 2 to 5 years. Natural durability varies from 18 to 30 months. Loss due to fungi and insects can be reduced by proper treatments at the time of stacking and storage. To prevent termite attack stacking is done on raised ground along with the application of lime sludge and 2 per cent BHC. Traditional non-chemical methods of preservation include controlling starch content by adjusting felling season, age of felling, water soaking and post-harvest transpiration. Other methods include baking on open fire, lime washing and other coatings. Preservative treatment of dry bamboos, the methods used are soaking, hot-cold process and pressure treatment (Kumar et al., 1994). USES This species is one of the two most important bamboos in India. It is found suitable for reclamation of ravine land. It is extensively used as raw material in paper mills and also for a variety of purposes such as construction, agricultural implements, musical instruments, furniture etc. Young shoots are commonly used as food. Decoction of leaves and nodes and silicious matter is used in the traditional medicine. |
D. strictus
D. strictus
D. strictus
