CONVENTIONAL METHODS OF BAMBOO PROPAGATION
Vegetative Propagation
  The bamboo plant consists of three morphological parts - the aerial part (the culm) and two underground parts (the rhizome and root). A bamboo propagule must develop all three structures. Failure in development of any of these structures leads to failure of a propagule (Banik 1980). Due to the scarcity of seeds, bamboo is generally propagated by vegetative methods. These include:

  • Clump division - offsets, rhizom,

  • Whole culm cutting,

  • Layering,

  • Culm-segment cutting,

  • Branch cutting and

  • Macroproliferation.
  These methods have been studied in different countries and each country has methods suitable for their own species. (Table1).

Clump divisions
  This is the traditional, and perhaps the most generally prevalent method of vegetative propagation (McClure 1966). Clump divisions are generally done in two ways - offset planting, and rhizome planting.

offset planting
  The term "offset " was designated by Deogun (1937) for bamboo propagules' each composed of the lower part of a single culm with the rhizome axis basal to it. According to Deogun, 1-or 2-year old offsets of Dendrocalamus strictus gave best results, while propagules consisting of material 3 years or more in age gave progressively poorer results. Over a century ago, Peal (1882) reported that propagation of bamboos by offset planting was common in the villages of Assam and Bengal. It is evident from Table 1 that offset planting is common in most bamboo growing countries.
  Both age of the offsets and their collection time have significant effect on their survival and growth in plantations (Banik 1991). Offsets of Bambusa balcooa, B. longispiculata, B. tulda, B. vulgaris, D. longispa thus, M. baccifera, Neohouzeaua dullooa and 0. nigrociliata were planted both in April and June. Success was higher (44-76%) when collected and planted in April than in June (3-38%). The younger (1 year old) offsets showed higher percentage of survival than older ones (2-3 year old). Thin walled species like M. baccifera, N. dullooa and 0. nigrociliata showed poor success in offset planting. In these species, success was obtained (30-40%) by planting rhizome assemblies (part-clumps) with 2-3 offsets at a time.

Rhizome planting
  Reports on the propagation of bamboos by rhizome planting are meagre (McClure 1966). Dabral (1950) described it as "the best method", but he did not mention the species or details of the method. The use of rhizomes for propagating bamboo has been limited to non-clump forming species (Uchimura 1977).
  Oh and Aoh (1965) mentioned that planting of rhizome cuttings, 40-50cm long, 10cm deep, gave good results in Korea. In propagating Shizostachyum lumampao, an endemic species of Philippines, Uchimura (1977) obtained success only by planting of rhizomes or offsets. This was usually done with 1-year old culms that were excavated along with their root systems. The culms were cut to about 1-m high and planted during the rainy season.
  McClure (1966) opined that planting of rhizomes might have advantage over offsets, being lighter and less bulky. However, he also mentioned that offsets could be physiologically more suitable for plantations as they have some foliage.
  Use of these propagules are practicable only in cultivating a few clumps, particularly within a small accessible area.

Whole culm cutting
  Kurz (1876) described this method as "by taking whole halms (culms) with their roots and burying them length-wise in the ground". Pathak (1899) tried propagation of Dendrocalamus strictus using 3-5 year old culm cuttings. Although sprouting was good in the initial stages, the cuttings failed to establish during summer. McClure and Kennard (1955) did some experiments with D. strictus and B. tulda and reported that 2-year old culms produced more propagules than 1-year old culms. The success was reasonable, but the procedure was cumbersome.

Layering
  The layered stem when rooted is detached to become a new plant. Three layering procedures for bamboos have been described (McClure 1966). These are:
  Ground or Simple layering: Either a whole culm or only the branch bearing part of it is bent down to the ground and into a shallow trench, fastened in place by means of hooked or crossed stakes, and covering it with suitable propagating medium.
  Stump layering: The 1-2 node stumps of severed culms are covered with a suitable propagating medium.
  Air-layering or marcotting: A culm is kept erect, and the base of each branch complement in the mid-culm range is surrounded with a suitable propagating medium, held in place by a suitable receptacle.
  McClure (1966) found that 1-year old culms of B. textilis and Guadua angustifolia, when bent down and covered with earth while still attached to the mother clump, satisfactorily produced little plants. According to him,this method was too cumbersome except in dwarf cultivars of B. mutiplex var. riviereorum. Cabandy (1957) obtained a survival of 28% for B. blumeana by ground-layering 1-year old culms pruned off branches.
  While studying the stump layering methods in B. longispiculata, McClure (1966) obtained only 25% rooted branches, but it increased up to 54% when the stumps were treated with 200 ppm IBA. He also tried the same method with 4 other species: B. textilis, B. tulda, B. tuldoides and D. strictus, and reported that either the plants died or did not produce any rooted propagules.
  In exploratory studies, McClure (1986) tried air layering of matured branch components of 1-year old culms of B. tuldoides and current year (developing) branch complements of Semiarundinaria fastuosa without achieving any success with either species. Cabandy (1957) obtained success (70%) in marcotting only with B. blumeana.

Culm-or Stem-cutting
  Propagation of bamboos through culm or stem segments is known as the culm-cutting or stem-cutting technique (McClure 1966, Troup 1921). Generally, culm segments of bamboos of 1, or usually 2-3 nodes bearing healthy buds or branches, have been used for propagation (McClure 1966). The branches on each culm segments are generally pruned to a length of less than 25cm and no foliage is retained. Such cuttings are usually set upright or at an angle, with at least one node well covered.
  As early as in 1899, Pathak used 2-node culm cuttings for propagating D. strictus in Orissa, India. The success was about 95% after one year, and finally all died after 2 years. Later, Dabral (1950) reported limited success in this species at Dehra Dun. Sharma and Kaushal (1985) obtained best rooting and survival in 1-node culm cutting taken from 1-10 basal nodes of 6-8 month old culm in the month of March (Spring). Good success and survival were also obtained in B. nutans, B. tulda, and D. hookeni by culm cutting methods (Bohidar 1989, Stapleton 1987). Surendran and Seethalakshmi (1985) reported that rooting and sprouting responses were significantly enhanced by the application of growth regulators. The success rate was 80% in B. arundinacea, 70% in D. strictus, 50% D. scriptoria while treated with hormone in contrast to the control 40%, 50% and 10%, respectively. In B. balcooa, they obtained 40% success in branch cuttings, and 60% in culmcuttings. Effective hormones were IBA and NAA.

  In Nepal, a good success rate (60-80%) from single node culm cuttings have been achieved in B. balcooa, B. nutans, D. hamiltonii, D. hookeni, and D. nigrociliata (Das 1988).
  Propagation studies in Sri Lanka showed that 2-node culmcuttings of some major bamboo species are more satisfactory than split culm-cuttings, and the technology is being gradually transferred to the planters (Vivekanandan 1987).

  In the Philippines, Chinte (1965) reported a 60% survival for B. vulgaris and 28% for Gigantochloa asper, whereas B. blumeana and G. levis failed to grow. Three node cuttings survived better than 2-node planting stocks, and the basal sections were superior to the middle and top sections. Another study on B. blumeana showed a greater percentage of survival (60%, 8%) in culm cuttings planted unsplit (Cabandy 1957). For G. levis, unsplit culm cuttings also gave better results, and the middle and top portions of the culm were the best material for propagation (Bumalong and Tamolang 1980). Mabayag (1937) found that the basal portions of culm cuttings of B. blumeana were better than the middle and top portion of the culm. In a separate study, 2-node split and unsplit (about 1-2 year old) culm-cuttings of 4 different bamboo species planted directly in the field showed better result (94%) after 3 months and poor results (11.7%) after 15 months of trial (Bumalong and Tamolang 1980). Suzuki and Ordinano 1977) obtained 45% survival of B. blumeana treated with IBA and 32% for controls; 80% for treated B. vulgaris and 75% for controls; 60% for treated D. merrillianus and 53.5% for controls. However, Uchimura (1977) found that, of the three growth regulators (IAA, IBA and NAA), cuttings treated with 100 ppm of IBA for 24 hours gave better rooting percentage and formation of longer roots in B. vulgaris. In a similiar study with B. blumeana using different concentrations of IAA, IBA and NAA, Bumalong and Tamolang (1980) observed that rooting was maximum with 600 ppm NAA. Palijon (1983) reported that cuttings treated with rooting hormones were higher in shoot production and the shoots were taller and wider in diameter than those of untreated cuttings, but there was no difference in survival rate at field level between them. Scientists also believed that the starch content and the levels of various nutrients in the cuttings might have influenced the rooting. Joseph (1958) found high amount of starch content in culm cutting of B. arundinacea during February and March. Banik (1987) emphasised that preparation of culm segments in the month of April-May from the mid-zone of a young culm was critical for obtaining successful results in B. vulgaris, B. balcooa, B. tulda, Dendrocalamusgiganteus, D. longispathus and Melocanna baccifera.
  Recently, Gonzales et al. (1991) from the Philippines reported that split-culm cuttings can reduce the weight of the planting stock in comparison to those produced as whole culm cuttings. They obtained 100 percent survival with cuttings of Bambusa blumeana, B. blumeana var. luzonensis, B. philippinensis, B. vulgaris, B. vulgaris var. striata and G. asper.
Branch cutting
  White (1947) reported that it was possible to propagate Gigantochloa verticillata and Sinocalamus oldhami by branch cuttings. Delgado (1949) and Mcclure and Durand (1951) also propagated bamboos by using branch cuttings, but with poor rooting percentages.
  Studies showed that in most bamboo species of Bangladesh, normal branch cuttings rooted well under mist tents, but the majority of them did not produce any new culm, owing to the failure of rhizome development (Hasan 1977). Such cuttings might survive up to 4-5 years only with the help of roots but without any further shoot production and clump formation (Banik 1980).
  Banik (1980) successfully induced in situ rooting and rhizome at the branch bases of some thick-walled bamboo species of Bangladesh. Artificial induction was possible by chopping the culm tops and removal of newly emerging culm. He termed these "pre-rooted and pre-rhizomed branch cuttings". Such cuttings performed better than normal branch cuttings (Banik 1984, 1987a). These cuttings have to be collected through excising the branch base from the nodes of the standing culms during April to June. For activating the aerial roots and rhizome, branch cuttings are to be inserted to a depth of 7cm in sand and maintained under overhead misting for one month. A propagation bed is a 3-layered sand, each layer being 7-10cm deep and made up as follows:

  • gravel and large size sand at the bottom

  • medium size sand in the middle

  • fine sand at the top
  In each layer clean, sand is placed so that the bed remains well-drained. A propagation bed is 1.2m wide and 12m long, situated on level ground in the nursery. Within 30 days each of the prerooted and prerhizomed branch, cuttings produce pro-fuse active roots in the propagation bed. Once profusely rooted, the cuttings are transferred to polythene bags and kept in the nursery. The average rooting and rhizome formation ability of these type of branch cuttings are 67% in B. balcooa, 70% in B. nutans, 93% in B. polymorpha, 90% in B. vulgaris and 63% in D. giganteus (Banik 1984, 1991). Like seedlings, cuttings also need aftercare in the nursery at least up to the next monsoon. Survival of these cuttings in the field is as high as high 85-97%.
Macroproliferation of bamboo seedlings

  Several methods of vegetative propagation are common in many grasses, e.g. use of tillers, culms, rhizomes or stolons (Langer and Ryle 1958). Like many other grasses, bamboo has the inherent proliferating capacity to reproduce itself probably due to its long interseeding period. By utilising this habit, an interesting technique has been developed by Banik (1987a) for multiplication of a seedling through the rhizome separation method. He termed the technique macroproliferation of seedlings. He reported that 5-9 month old seedlings of B. tulda can be multiplied 3-5 times in number through this technique. Every year the seedling can be multiplied at the same rate and a big portion of them may be planted while keeping a stock for future macroproliferation. The survival rate of these multiplied seedlings is 90-100%. It has also been observed that seedlings of B. arundinacea, B. tulda, and D. strictus raised in big-sized polythene bags (15x23cm) produced a higher number of shoots (6-8 number) within one year than in small sized bags (10x15cm). Therefore, seedlings raised in big polythene bags produced a higher number of multiplied seedlings (5-7 times), whereas seedlings in a small-sized bag could produce only 2-3 number of multiplied seedlings. Later, Adaresh Kumar et al. (1988) also used this method successfully for multiplication of the seedlings of B. arundinacea, D. strictus, and D. hamiltonii. Recently, in India a detailed plan has been developed by Adaresh Kumar (1991, 1992) for continuous production of field plantable saplings in massive numbers viz., B. arundinacea-49000; B. tulda-25000; D. hamiltonii46000; and D. strictus-36000 (or in multiples) every year for any desired number of years.
  Advantages of this method are that once seedlings of a bamboo are available, the process can be continued at least for a number of years. Proliferated seedlings remain small in size due to continuous rhizome separation1 thereby making it easy to handle and transport them (Banik 1987, Tewari 1992). However, Banik (1987a) suggested that seedling multiplication in this way should not be continued for a very long time since the time gap between the last multiplication and subsequent flowering gets shorter. As a result, the last multiplied seedlings might start flowering due to their physiological maturity before attaining the commercial culm size.
Propagation through Seeds
Seed characters and measurements
  As bamboos produce seeds after long time intervals, the knowledge on different aspects of seed propagation is very limited. Bamboo produces one-seeded fruits with thin pericarp adnate to the seed coat, known as a caryopsis and covered with a number of persistent glumes (Gamble 1896). Kurz (1876) described the fruit of Melocalamus compactiforus as "a small wood-apple", and the fruit of Melocanna baccifera as "berry-like". Seeds of bamboos are very different both in size and weight depending on the species. Seeds are generally small, grain-like and wheat-coloured; but those of M. baccifera are onion-shaped, big and green coloured. Generally large-sized bamboos produce smaller seeds than small-sized bamboos (Anantachote 1988).

  Seed production per clump varies from 3~80g in B. arundinacea var. spinosa, 15-17g in B. glaucescens, and 40-90g in Dendrocalamus longispathus. One full grown clump of Melocanna baccifera produces 5-7kg seeds. In general, the number of seeds per kg varies from 13,000-15,000, depending on the species (Banik 1987b, Liese 1985). According to Anantachote (1987), the weight of 10 seeds of T. siamensis, B. nutans, and Gigantochloa hasskarliana is O.62g, O.30g, and O~38g, respectively.
Seed collection and processing
  In bamboo species, mature seeds drop on the ground and become exposed to predators, such as birds, especially chickens and pigeons in the homestead, and to rats, porcupines and wild boar in the natural forests. Birds and squirrels also eat seeds while on the plant. Only careful collection can overcome the predation problem. Seeds can be collected both from the clumps and from the ground. Generally, seeds produced in the early part (mid-February to May) of the season are healthy and more viable.
  Except for M. baccifera, glumed seeds of all other species can be separated from debris and empty seeds by floating in water. As the seeds of M. baccifera are big and not covered with glumes, they can be separated easily from debris and unwanted materials.
Seed germination, longevity and storage
  Seeds of different bamboo species possess embryos at their swollen stalk-ends and, therefore, care should be taken to bury this portion in the soil during sowing to protect germinating radicles from being desiccated. Seeds should be sown in polythene bags just after collection. Bamboo seeds germinate at higher percentage under shade than in direct sunlight. Thus, bamboo seeds can be considered as negatively photoblastic (Banik 1991). The germination media (soil and cowdung 3:1) should be wet, but not waterlogged. Seeds start germinating within 3-7 days of sowing and continue up to 15-25 days (Banik 1987b).

  Banik (1991) reported that for M. baccifera, the seed weight has a significant effect on seedling survival. Seedlings survive up to 70-75% when raised from seeds heavier than 50 g, while it drops to 50% when raised from light weight seeds (7-17 g). Different types of abnormalities, such as rootless plumules, stunted radicles and radicles growing upward, were observed in seedlings of M. baccifera produced from light weight seeds.
  It was found that the fresh seeds of B. arundinacea var. spinosa, B. tulda and B. Jongispathus germinated better than stored ones (Banik 1987b). The seeds have a germinative power which lasts only 1-2 months. It was possible to preserve the seed viability of a bamboo species (Phyllostachys sp.) by storing the seed over calcium chloride at room temperature. Sur et al. (1988) observed that for maintaining the vigour and viability of seeds ofD. strictus, soaking-drying treatment with low concentration of disodium hydrogen phosphate (10-4M) proved to be better than water. However, the seeds of D. strictus could be stored over silica gel or anhydrous calcium chloride in a desiccator, or at 3-50C ambient temperature after reduction of its moisture content to 8% (Varmah and Bahadur 1980). Seed lots with 67% germination capacitiy were stored under these three conditions and exhibited 51,54 and 59% germination, respectively, after 34 months. Similarly, Banik (1987b) reported that it was possible to increase the seed longevity period of B. tulda up to 18 months by storing over silica gel in a desiccator. The fleshy seeds of M. baccifera, when stored in a air-conditioned room, retained viability up to 45 days, while it was only 35 days in normal room conditions, and prolonged further up to 60 days when stored with dry sand in jute bags. The seeds of M. baccifera can be carried with dry sand in jute bags during long distance transportation to minimise damage and to retain viability (Banik 1991).
Seedling nursing and management

  Initially, seedlings do best in partial shade compared to direct sunlight. Complete shading over seedlings should be discouraged. The emergence of shoots is successive. The new shoots are bigger and taller than older ones. The germinating plumules are very thin (1-2 mm diameter) in B. tulda and thick (4-6 mm) in M. baccifera. Within 1-4 weeks, plumules elongate rapidly into stems bearing single leaves arising alternately. The stems of B. tulda, B. longispathus, and B. polymorpha are more or less woody in nature, but M. baccifera has a soft and succulent stem with vigorous growth. M. baccifera seedlings become most elongated (175 cm) and thick (0.8 cm, dia.) at 3 months of age (Banik 1991).
  A rhizome system starts to develop in the seedling 1-2 months after germination, and at a young stage, the rhizome movement is strongly geotropic. Therefore, roots and rhizomes of a seedling penetrate the neighbouring polythene bags of other seedlings in a nursery. This creates a mass of twisted and intertwined roots and rhizomes of seedlings. As a result, the roots and rhizomes are damaged at the time of transportation. Frequent shifting of seedlings from one bed to another helps in minimising the root rhizome intermingling. Seedlings need regular weeding and daily watering in the nursery.
Wild seedlings
  Wild seedlings of bamboo look like rice or wheat seedlings and are often seen on the ground just below the flowering mother clumps. The numbers of seedlings can be very profuse and they often form a thick mat on the ground. These dense seedlings compete strongly for survival. Such seedlings should be thinned out to minimise the competition (Banik 1987a, 1989, 1991). Wild seedlings so collected should be brought to the nursery and transplanted to polythene bags containing soil mixed with cowdung (3:1) At the beginning, seedlings have to be kept under shade for 3-5 days for hardening, then placed them under partial shade. Two-to four-leaved stage of wild seedlings of B. tulda and D. longispathus are best for collection, while in M. baccifera germinating seedlings are best. For better survival (about 80-90%) in the field, less than one-year old seedlings should not be transplanted. The rainy season is the best time for planting of seedlings in the field.

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