Micropropagation of Banana Varieties (Musa spp.) Using Shoot-Tip Culture

A study was carried out at the Tissue Culture Laboratory of Melkassa Agricultural Research Centre, Ethiopian Institute of Agricultural Research (EIAR) to investigate the effects of different types and concentrations of cytokinin's and auxins on shoot initiation and multiplication, and in vitro shoot rooting of three banana varieties using shoot-tip explants. Shoot initiation was greater on Murashige and Skoog (MS) basal medium supplemented with 3 mg/l N6-benzylaminopurine (BAP) for Dwarf and Giant Cavendish while 2 mg/l for Poyo varieties. Among the different concentrations of plant growth regulators (PGR) tested, MS medium supplemented with combinations of BAP and indole-3-acetic acid (IAA) at 3+0.4, 4+0.4 and 3+0.2 mg/l for Dwarf, Giant and Poyo respectively, were best combinations for high rates of shoot proliferation and elongation. Further multiplication of shoots required up to 5 times sub culturing of 1 month each on the same media combination. In this study, about 3-fold multiplication rate was achieved during every subculture. Better rooting was obtained when the shoots were cultured on MS medium with 2.12 mg/l α-naphthaleneacetic acid (NAA) for Dwarf and Giant while 1.74 mg/l indol-3-butyric acid (IBA) for Poyo. In vitro rooted plantlets were transferred to the lighthouse for acclimatization and hardening. The best growth was recorded for plantlets transplanted on potting media containing a 3:1 ratio (v/v) of sugarcane filter cake and sand. The hardened plants were transferred and well established to the field.本研究于埃塞俄比亚农业研究所(Ethiopian Institute of Agricultural Research, EIAR)的梅尔卡萨农业研究中心组织培养实验室开展，旨在探究不同类型及浓度的细胞分裂素(cytokinin)与生长素(auxin)对以茎尖外植体(shoot-tip explants)为材料的三个香蕉品种的芽诱导与增殖，以及离体芽生根的影响。相较于其他培养基，添加3 mg/L N6-苄基腺嘌呤(N6-benzylaminopurine, BAP)的Murashige和Skoog(MS)基础培养基更利于矮香芽蕉(Dwarf Cavendish)与大香芽蕉(Giant Cavendish)的芽诱导，而波约(Poyo)品种的最佳诱导浓度为2 mg/L BAP。在所测试的不同浓度植物生长调节剂(Plant Growth Regulators, PGR)组合中，针对矮香芽蕉、大香芽蕉与波约品种，分别采用3+0.4、4+0.4与3+0.2 mg/L的BAP与吲哚-3-乙酸(indole-3-acetic acid, IAA)组合，为实现高芽增殖率与伸长率的最优配比。进一步的芽增殖需在相同培养基配比下进行至多5次继代培养，每次培养周期为1个月；本研究中，每次继代培养可实现约3倍的增殖倍率。当将芽苗接种于添加2.12 mg/L α-萘乙酸(α-naphthaleneacetic acid, NAA)的MS培养基时，矮香芽蕉与大香芽蕉的生根效果更佳；而波约品种则以添加1.74 mg/L吲哚-3-丁酸(indol-3-butyric acid, IBA)的MS培养基生根效果最优。离体生根的组培苗被转移至光照驯化室进行驯化与炼苗处理。以3:1(体积比)的甘蔗滤饼与沙子混合作为盆栽基质时，移栽组培苗的生长表现最优。炼苗完成后的植株可被移栽至大田并成功定植。