Studies on shoot and root induction of eight commercial banana varieties of West Bengal by macro-propagation technique

For mass multiplication of healthy planting materials, shoot and root were successfully induced by macro-propagation technique from eight commercial banana varieties grown in West Bengal, viz., Grand Naine (AAA), Robusta (AAA), Martaman (AAB), Champa (AAB), Kanthali clone-1 (ABB), Bagda Kanthali (ABB), Baish Chhara (ABB) and Behula (ABB). Corms prepared by decapitation and pairing of healthy suckers (4-5 months old) were planted in growth media bed (containing 2 kg sawdust + 30g Trichoderma viride/Bacillus subtilis + 30g VAM per corm) and treated weekly with 25 ppm 6-benzylaminopurine (BAP) solution. However, each variety was significantly different from others with respect to induction time and number of primary, secondary and tertiary shoots induced and the number and length of primary and secondary roots induced. The time required for induction of primary shoot varied from 19.75 days in Grand Naine to 28.25 days in Bagda variety. The number of induced primary shoot was recorded higher (3.23 to 3.40/corm) in varieties under AAA group, compared to the AAB (2.70-2.90 shoots/corm) and ABB groups (2.20-2.50 shoots/corm). Similar trends were also recorded for induction of secondary and tertiary shoots. The number of tertiary shoots produced per corm was maximum (24.23) in Grand Naine and minimum (9.61) in Kanthali variety. The tertiary shoots were separated from corms at 2-3 leaves stage and planted in sterile sand bed by basal treatment with rooting hormone (IBA) @ 5 ppm. Two weeks after treatment, primary roots were induced, which was higher (2.20-2.65/plantlet) in the varieties under AAA group, compared with 1.23 to 2.29/plantlet in AAB and ABB groups. These plants were planted in polythene packets containing hardening mixture and hardened for 60 days under shade net house. After hardening, the number of primary and secondary roots were recorded maximum (10.80 and 35.50/plant, respectively) in Grand Nain and minimum (9.20 and 31.60/plant, respectively) in Baish Chhara variety.