EVALUATION OF DIFFERENT ACCLIMATIZATION METHODS OF IN VITRO BANANA (Musa acuminata) PLANTLETS

Three sets of experiments were involved in this study. They were carried out at the Plant Tissue Culture Laboratory, Department of Horticulture and Agricultural Biotechnology, Yezin Agricultural University from December, 2012 to July, 2014. Experiment I was aimed at investigating the effect of different substrates in acclimatization stage on micropropagated banana plantlets. Randomized Complete Block (RCB) design was employed with three replications. The treatments were sand:garden soil, sand:compost, sand:burnt rice husk, sand:vermicompost, sand only, sand:garden soil+arbuscular mycorrhizal fungi (AMF), sand:compost+ AMF, sand:burnt rice husk+AMF, sand:vermicompost +AMF and sand+AMF. In Experiment II, effects of sugar concentrations and agar levels on the in vitro acclimatization were studied on the ex vitro acclimatization of micropropagated banana plantlets. Two factors factorial experiment in RCB design was used with 30 replications. Three levels of sugar concentrations (10, 20, 30 g.L-1) and three levels of agar medium (3, 5, 7 g.L-1) were studied. In Experiment III, the effect of pre-treatments on acclimatization of in vitro grown banana plantlets were studied. RCB design with three replications was used. The treatments were control (water), homai, ferti-start, atonik, moralmone, ferti-start+ homai, atonik+ homai, moralmone +homai. Among different substrates in acclimatization stage, the combination of sand + burnt rice husk +AMF provided the highest values in number of leaves, leaf area, fresh weight and dry weight of micropropagated banana plantlets. Sand only substrate gave the highest survival percentage. Among the sugar concentrations and agar levels in in vitro hardening, 30 g.L-1 of sugar and 3 g.L-1 of agar gave the maximum values in most parameters studied. The maximum survival percentage was observed on 30 g.L-1 sugar + 3 g.L-1 agar and 30 g.L-1 sugar + 5 g.L-1 agar in in vitro acclimatization to ex vitro condition. According to pre-treatments in acclimatization, the plantlets treated with homai gave the highest results in most parameters. Thus, it can be concluded that substrates which have good aeration are more important for micropropagated plantlets during the acclimatization period. 30 g.L-1 of sugar and 3 g.L-1 of agar are the best sugar concentration and agar level for micropropagated banana plantlets during in vitro acclimatization. Homai should be used as a pre-treatment on acclimatization stage of in vitro grown banana plantlets