Effect of adenine sulphate, casein hydrolysate and spermidine on in vitro shoot multiplication of two banana varieties (FHIA-21 and PITA-3)

Abstract

A highly reproducible and efficient in vitro shoot regeneration system was developed for two banana varieties (FHIA-21 and PITA-3) using shoot tip as explant. Shoot tip was inoculated onto Murashige and Skoog (MS, 1962) medium supplemented with cytokinins [benzylaminopurine (BAP), kinetin (Kin) and 2-isopentenyl (2-iP)] and additives [Adenine sulphate (Ads), spermidine (Spd) and casein hydrolysate (CH)] for shoot multiplication. In all varieties, the maximum number of shoots and shoot length was obtained with 3 and 4 mg/L BAP, respectively. This rate was further enhanced by adding Ads (25 mg/L), CH (25 or 50 mg/L) and Spd (100 or 200 mg/L). In vitro raised shoots were successfully rooted on 1 mg/L 2-iP in combination with 0.5 mg/L naphthaleneacetic acid (NAA). Rooting was significantly enhanced by adding casein hydrolysate (25 or 50 mg/L). The well rooted plantlets were successfully acclimatized on different substrates (compost, forest soil, sand, forest soil + sawdust from dead tree and sand + sawdust from dead tree). The compost substrate  was found to be preferable. Finally,  after one month in the greenhouse, the hardened plants were transfered to the field environment for utmost survivability.   Key words: Additives, banana, cytokinins, in vitro shoot multiplication, rooting, shoot tip.