Propagation

Bamboos are propagated either by seeds or vegetative means (offsets, division, culm/ rhizome cuttings or layering). In general, bamboos are monocarpic, i.e. they flower only once and die after producing seeds. Most of the economically important bamboos flower gregariously at long intervals of 30-40 years. Although large quantities of seeds are produced during gregarious flowering, they are viable only for about six to eight months. Seeds can be germinated in nursery beds and pricked out into polybags of size 18 cm (flat width) x 22 cm. One year-old seedling can be used for planting. However, when seeds are not available, bamboos are propagated vegetatively.

Propagation by offsets is the common method of vegetative propagation. One-yearold culms in a clump are given a slanting cut at about 90 to 120 cm above the ground. The rhizomes to which they are attached are dug out with the roots intact. The shoot portion is then cut off to a length sufficient to include a well-developed bud. These offsets are planted out sufficiently deep in the soil to cover the first two or three nodes. Planting should be carried out immediately before the rainy season. During extraction care must be taken to avoid damage to roots and rhizomes of mother clumps.

Work at the KFRI has shown that using rooted culm cuttings is a viable alternative to the laborious offset method. For vegetative propagation using culm cuttings, extract 2 to 3 year old culms from healthy clumps by cuttings just above the first node during MarchApril. Trim the leaves and side branches without injuring the auxillary buds. Prepare two-node cuttings (leaving about 5-7 cm on either side of the nodes) using a sharp knife or saw. Make a small slit (about 2 m long and 1 cm wide) or drill holes (about 7 mm diameter) in the middle of the inter node. Wrapping in moist gunny bag or embedding in boxes containing moist saw dust might minimize exposure of the cuttings. Pour about 200 ml of NAA (1-naphthalene acetic acid) solution (100 ppm) carefully into the culm cavity through the slit and close the slit/hole by wrapping with a polythene strip. Ensure that the polythene wrapping is tight so that the solution does not leak out. After extraction, the culm cuttings should be treated with NAA as quickly as possible.

Prepare raised nursery beds of 10 m x 1 m and fill with a mixture of soil and sand (3:1). One week prior to planting, drench the nursery bed with 30 litres of carbendazim 0.05 per cent to prevent fungal attack. Place the cutting horizontally (the opening facing upwards) across the nursery bed. About 50-60 cuttings may be conveniently planted in a raised nursery bed. Cover the cuttings with a thin layer of soil. Provide shade and water the beds regularly till the onset of monsoon but avoid waterlogging. Rooted cuttings can be transplanted to the field in about four months. Cuttings sprouted and rooted at both the nodes of a culm cutting must be separated carefully through the middle to get two plants.

Propagation by division is usually done in the case of dwarf bamboos, which are easy to handle. It involves splitting / dividing the mass of rhizomes and planting out the culms in small clumps with two or three culms attached. Other methods of vegetative propagation include rhizome cuttings and air layers. Sections of fresh living rhizome of the preceeding year about 15 to 30 cm long containing at least one bud and air layers form successful means of propagating some bamboo species.