Branch cutting is a simple and easy method of propagation and is mainly used for species with swollen branch bases, aerial roots, and prominent branches. Primary and secondary branches are effective, however, the success of rooting is not as high as in culm cuttings. Considering the availability in large numbers, and ease in handling, even 50% rooting is good for this method of propagation to be successful. The ideal time for propagation using this method is early monsoon, especially after pre-monsoon showers or within three months of the onset of monsoon.
This method is found to be effective in the case of species like Bambusa balcooa, B. vulgaris, Dendrocalamus stocksii, etc., mostly thick-walled species stout branches and having prominent primary branches from the base of the culm, but a very low survival percentage is reported in the case of species like Dendrocalamus giganteus and Thyrsostachys oliveri.
For the preparation of branch cuttings, the branches are excised using a sharp knife or saw. Cuttings are made by trimming the leaves and small branches. Cuttings with four to eight nodes are made, and the basal part is dipped in the GRS solution for 24 hours. The treatment with GRS enhances rooting response in-branch cuttings, and the dip method of treatment is very effective. The selected branches can be dipped in rooting hormone (GRS) solution (IAA, concentration - 200 ppm or NAA for a few hours (preferably overnight), and soaking helps in better root formation and higher survival. The time taken for rooting is about four to eight months, and rhizome formation takes still longer periods of about a year. In some cases, if propagation is carried out during the pre-monsoon season, no hormone treatment is required. Generally, the sand bed established in partial sunlight can be used for planting, and before planting, dip the cut ends of the branch cuttings in fungicide (1 ml/gram per litre of water) for 5 minutes.
The exposed cut end of the branch cutting should be covered with wax or cow dung. Watering can be done at least 2 to 3 times a day, depending on the climatic conditions. Sprouting of branch buds appears in 10 to 20 days. Depending on the species of bamboo and the season of branch cutting collection, the root formation ranges from four to eight months, and rhizome formation takes still longer periods of about a year. Then it can be transplanted into poly bags (size - 15 cm X 20 cm or bigger) filled with the potting medium (soil, sand, and manure; 1:1:1 or soil and compost;3:1).
Preparing pre-rooted and pre-rhizomed branch cuttings can reduce the time taken for rooting and rhizome development in branch cuttings. In some species, natural aerial rooting and rhizome formation is seen, and planting material can be collected from this region. Chopping off the top part of the culm and covering the nodal buds with moist media like moss or coir can also induce pre-rooting.
Planting and aftercare
Planting and aftercare are similar to culm cuttings. Sprouting and rooting time depends on the season and varies from 30 to 70 days. When rooting occurs, the cuttings should be removed from nursery beds and poly-potted.