In vitro mass propagation of Dendrocalamus asper (Giant bamboo) through direct organogenesis

Abstract

Dendrocalamus asper (giant bamboo) is a clumping type of bamboo belonging to the Poaceae family. Due to its economic and environmental value, demand for this species has increased tremendously. Conventional propagation methods have limitations due to low seed viability and the lack of healthy clumps. Therefore, an in vitro mass propagation protocol was developed to provide healthy plants for large-scale plantations. Seeds were used as the explant and they were surface sterilized and cultured on MS medium free of growth regulators. Nodal segments taken from in vitro germinated seedlings were used for shoot initiation. The best medium for shoot induction (MS medium supplemented with 0.0–2.5 mg/L BAP), best medium for multiple shoot induction (MS medium supplemented with 0.0–5.0 mg/L BAP), effect of shoot cluster size (shoot clusters containing 1–4 shoots) and effect of physical state of the medium (semisolid and liquid media) on multiple shoot induction were determined using shoots per node, mean shoot length and mean number of leaves per shoot after 6 weeks of incubation. Elongated shoots were transferred into a rooting medium and the best medium for root induction (MS medium supplemented with 0.0–5.0 mg/L IBA and IAA) and effect of cluster size (shoot clusters containing 1–4 shoots) on rooting were determined using the number of roots and root length after 6 weeks of incubation. All the cultures were maintained under a 16-hour photoperiod. Well-developed plantlets were transferred to coir pellets and after four weeks transferred into different potting mixtures containing different combinations of sand, compost and coir dust. Unless otherwise mentioned there were at least twenty replicates in all treatments. The highest mean number of shoots per node (16.87±0.52), mean shoot length (4.12±0.27 cm) and mean number of leaves per shoot (4.80±0.33) were observed in the MS medium supplemented with 1.0 mg/L BAP. The MS medium supplemented with 2.0 mg/L BAP was the best for multiple shoot induction, shoot cluster with 3 shoots was the best cluster size and the liquid medium had a better effect on shoot multiplication. The half-strength MS medium supplemented with 2.0 mg/L IBA was the best for in vitro root induction with the highest mean number of roots (7.15±0.77) and a mean root length of 10.79±1.11 cm. Shoot clusters with 3 shoots was the best cluster size for root induction. A sand: compost: coir dust (1:1:1) mixture was the best potting mixture giving 100% survival. These findings provide a reliable micropropagation protocol for D. asper, which holds great promise for meeting the growing demand for bamboo resources and promoting sustainable bamboo cultivation.