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    SCIENTIFIC CORRESPONDENCE

    CURRENT SCIENCE, VOL. 91, NO. 1 1, 10 DECEMBER 20061462

    Clonal propagation of bamboo (Dendrocalamus strictus)

    Bamboo grows naturally in many typesof forests. About 50% of the annual pro-

    duction of bamboo in our country is usedby various industries like pulp, paper,rayon, mat boards, besides agriculturalimplements. It is also used for makingbaskets, bridges, coffins, beds, toys andweapons. A grove of bamboo at groundzero in the area that destroyed Hiroshimain 1945 sprouted new shoots withinmonths1. The distribution of bamboo inIndia is largely governed by rainfall,temperature, and altitude and soil types.In recent years bamboos are in great de-mand; but nonavailability of sufficient

    quantity of saplings and seeds are themajor problem.Dendrocalamus str ictus is most com-

    monly called as solid or lathi bamboo.The species is widely distributed in drydeciduous forests and grows rapidly inall climatic conditions. It grows better inthe drier parts and on sandstone, graniteand coarse grained soils with low mois-ture-retaining capacity and soils with pH5.57.6. It grows more than 8 feet in 6-months. The pulp is used for makingquality paper and the clumps, beingstrong and elastic, are used for lathies,

    shafts, axe handles, walking sticks, agri-cultural, and industrial implements andtherefore it is rightly called as poormans timber.

    The major problem in the propagationofD. st ric tus is the erratic flowering andnon-availability of seeds on regular basis,besides low viability of seeds. Moreoverthe seeds have to be stored in 3 to 5 Cafter reducing the moisture (8%) orstored in a desiccator with anhydrouscalcium chloride. Under these circum-stances, other techniques of propagation

    become important. Development of novelmethods of propagation by tissue culturetechniques, micropropagation and macro-propagation including clonal propagationis desirable for large-scale application. Inrecent years vegetative propagation tech-niques are standardized and adopted toimprove self-incompatible bamboos withpoor seed set2. Attempts to develop low-cost planting stocks of bamboo usingculm-cuttings 3 and in vitro techniques4,5are of paramount importance in bambooimprovement. We describe here an effi-cient technique of clonal propagation ofbamboo.

    Mature stem cuttings of 210 cm girthfrom 5 to 6 year-old plants were clonally

    propagated. The stem cuttings of 40100 cm height with 37 nodes were di-rectly planted in polybags. About 170explants of different sizes were used inthe present study. Mature explants (56years old) were classified into four cate-gories according to size, i.e. girth 23 cm,36 cm, 69 cm and 912 cm. These ex-plants were planted in different sizes ofpolybags with red soil + cocopit + farmmanure (1:1:1). The polybags were placedin a mist chamber.

    Seeds collected were dehusked andwashed thoroughly under running tapwater for 20 min. Seeds were sterilizedwith Bavistin (0.1%) for 15 min and fur-ther treated with HgCl2 (0.1%) for fivemin, finally washed with sterile disti lledwater 56 times and were inoculated ini-tially on MS media supplemented with2 mg/l 2,4-D.

    The explants propagated through stemcuttings showed response in about two

    weeks. Nodal branching was observed andthe pattern varied considerably dependingon the basal or apical node (Table 1).Each stem cutting had four to six nodes(Figure 1). In general, younger axillarynodes gave better response when com-pared to the basal nodes of the samestem.

    The rooting pattern differed consid-erably depending on the age of the stemcuttings of explant. The older explantsexhibited bushy type of rooting com-pared to top younger cuttings, where thetap root system with rhizomes were ob-served (Figure 2). The mature explantsalso exhibited tillering after 34 monthspresumably by rhizome. Since rhizomescan be selected and propagated as superiorclones, they were separated from seed-lings (Figure 3) grown in polybags andnew seedlings were obtained. Culms are

    Figure 1. Clonal propagation ofDendrocalamus str ictus through stem cuttings.

    Figure 2. Pattern of rooting of stem cuttings.

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    SCIENTIFIC CORRESPONDENCE

    CURRENT SCIENCE, VOL. 91, NO. 11, 10 DECEMBER 2006 1463

    Table 1. Initiation of root/nodal branches of different stem cuttings

    Girth Height No. of Response Nodal Nodal branches Nodal branches/(cm) (cm) explants (%) branches/node (average height) node (average)

    23 5072 78 71.1 23 17.8 3

    36 4087 49 75.5 35 13.1 589 5582 31 67.7 34 19.1 3912 5283 21 71.1 36 83 5

    generally produced from young rhizomes,but under exceptional conditions, two-year-old rhizomes also produced culm-beds.More than one culm was found growingin one year from the rhizome which requiredturgescent conditions of high relativehumidity. Dense shade and heavy weedswere detrimental to its growth. In thisparticular experiment 2000 rhizomes weretransferred.

    The seeds inoculated on MS media

    germinated after 10 days. The embryos

    were collected in sterile condition andinoculated initially on half strength MSmedia supplemented with 2 mg/l BAP.From the explant, multiple shoots (130180) were derived in 4050 days and theseshoots were subcultured for every 15days for better multip lication rate (Figure4). The shoots were then transferred ontothe half st rength MS medium with 2 mg/lIBA for rooting. After 15 days the rootedplants were transferred to polybags (Figure

    5). This cost-effective technique in bam-

    boo micropropagation has added advan-tage by rapid multiplication of superiorgermplasm efficiently. Clonal propaga-tion through matured stem cuttings willprovide definite advantage in immediateage transfer and will save time in pro-pagation compared to seedlings. The addedadvantage is that the superior clones canbe directly propagated. This techniquecan be adopted for large-scale plantationof wastelands and saline soils to meet the

    growing needs ofD. str ictus.

    Figure 3. Propagation through rhizomes.

    Figure 4. Induction of multiple shoots from seeds in tissue culture.

    Figure 5. Tissue culture rooted plantlets in polybags.

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    SCIENTIFIC CORRESPONDENCE

    CURRENT SCIENCE, VOL. 91, NO. 1 1, 10 DECEMBER 20061464

    1. Hutchinson, J., Reader s Digest, April2002, pp. 8388.

    2. Koshy, K. C. and Gopalkumar, B., Curr.Sci ., 2005, 89, 14741476.

    3. Kumar, R. and Pal, M.,J. Bamb oo Rattan ,2004,3, 401409.

    4. Nadgauda, R. S., John, C. K., Joshi, M. S.,Parasharami, V. A. and Mascarenhas, A. F.Plant, Cell, Tissue Organ. Cult., 1997, 48,181188.

    5. Saxena, S. and Dhawan, V., Plant Cell Rep.,1999, 18, 483443.

    6. Mehta, Usha, Rao, I. V. R. B. and MohanRam, H. Y., In Proceeding of Vth Interna-tional Congress of Plant Tissue and CellCulture. Plant Tissue Culture, Tokyo, Japan,

    1982.

    ACKNOWLEDGEMENT. I thank NATP,CRIDA, Hyderabad for financial support.

    Received 20 January 2006; revised accepted25 August 2006

    G. M. REDDY

    Prof. G.M. Reddy Research Foundation,4-123/E, Swaroop Nagar, Uppal,

    Hyderabad 500 039, India

    e-mail: [email protected]

    Scale structure of a cobitid fish, Cobitis linea (Heckel, 1849) usingdifferent modes of SEM

    Detailed structure of the fish scale can behelpful in the identification of fishes up tomajor groups13, species levels46, phylo-geny7,8, sexual dimorphism9, age deter-mination1013 and pathology of fish scaledue to water pollution of the waterbody1416 and for growth studies1726.Studies on the scale structure of com-mercial fishes1721 have been undertakenand these studies have been successfullyused for growth studies2226 and calculationof minimum harvestable size27 so that legal

    fishable size can be prescribed for thedetermination of old age in the commer-cial fishes11 and also the pollution statusof the waterbody1416,28. Due to somesubjective reasons, in the past most ofthe lepidological studies are made on thecommercial fishes11,1921,23,24,26,27.

    Recently it has been reported that dueto loss of fish habitat as a result of watermanagement practices, release of efflu-ents into the natural waterbodies andseveral anthropogenic activities, most ofthe fish species are under different typesof threats as is evidenced from the

    squeezing of geographical limits and thereduction in the s tocks of most of the fishspecies29. In some cases, the fish com-munity structure is completely disrupted.Due to the reduction in the fish stocks,fish biologists are unable to get a largenumber of specimens for studies relatingto fish bionomics. Under these circum-stances, lepidological study is the bestalternative as fish scale is considered tobe the best tool in fish biology30,31.

    During a literature survey, it has beenfound that age and growth studies onminnows are rarely attempted and co-bitids are completely ignored11. These

    two groups of fishes form one of the impor-tant links in the fish community structurein hillstreams3234, hence standardizationof the scale structure of the fishes be-longing to these two categories help inunderstanding their bionomics. Further,cobitids live at the bottom and are con-sidered to be the natural scavengers.Their presence indicates that the water isregularly cleaned. Hence, their presenceis encouraged in the fish aquaria for thenatural cleaning of the glass walls.

    An attempt has been made here tostudy the ultrastructure of the scale of ancobitid, Cobitis linea (Heckel, 1849) em-ploying different modes of SEM collectedfrom the streams of south-west Iran. InIran, this group of fishes is generally knownas sag mahi, meaning dogfish in Per-sian and equivalent to loach in English.

    The fishes were collected by one ofthe authors (HE) using cast-net, scoop-netand ordinary insect net having mesh sizenot more than 5 mm during March 2005.The scales were gently removed withfine forceps from the left side of the

    body between the dorsal fin and lateralline in such a way that while removing thescales no damage is done to the scale.Immediately after their removal, thescales were cleaned mechanically using afine brush and rinsed with triple distilledwater. The cleaned scales were dehy-drated in 30, 50, 70% ethanol and driedon filter paper. The scales were not putin absolute alcohol as 100% ethanolcauses the scale margins to curl. To avoidcurling, after 70% ethanol, the scales werekept between the microslides for 23 days.The cleaned and dried scales were mountedon metallic stubbs by double adhesive

    tape with dorsal surface upward and ven-tral surface sticking to the tape andcoated with a 100 thick layer of goldin a gold coating unit. The gold coatingovercomes the problem of charging andbeam damage. An additional advantageof gold coating is to improve the strengthof secondary electron signals from thespecimens surface. The scales were viewedunder vacuum in a JEOL JSM6100 scan-ning electron microscope at an accelerat-ing voltage of 20 kV at low probe current.

    Various images of the scales were recordedon the photographic film. When gold-coated scales were not being viewed, thestubbs were stored in a desiccator to avoidmoisture.

    The different modes of SEM such assecondary electron image (SEI, low en-ergy electrons), back scattered electronimage (BEI, high energy electrons), mixedsignals of both SEI and BEI and reversepolarity (negative of mixed signals) havebeen employed for the study of scalemorphology35 (Figure 1ad). For the detailsof the circuli, X and Y modulations have

    been use35 (Figure 1ef).The length and breadth of the scale of

    C. linea (Heckel, 1849) from Iranianfreshwaters is almost the same havingnearly circular shape (Figure 1 ad). Thescales maintain the same morphologicalproportions located on the different partsof the body. The scales present below thedorsal fin, above the lateral line are larg-est and those on the other parts of bodyare smaller in size. As the scale from thisregion depicts all the features, this scalehas been designated as key scale. Thedistinct focus which lies in the posteriorpart of the scale divides the scale into an-