IN VITRO CALLUS INDUCTION AND SUBSEQUENT PLANTLET REGENERATION IN SWEET POTATO (Jpomoea batatas L.)

Abstract

Experiments on induction of callus in vitro and subsequent regeneration of plantlets in three high dry matter content of sweet potato germplasms such as 368572.36, 322300.92 and 471068.05 were conducted during July to December, 2005. For induction of callus, three levels of each of BAP ( 0, 2.0 and 4.0 mg/I ) and NAA (0, 0.05 and 0.10 mg/I) and for regeneration of plantlet, BAP (0, 2.0 and 4.0 mg/I) and IBA (0, 0.5 and 1.0 mg/l) with MS basic salts were used. The germplasms did not vary significantly for most of the parameters studied. Either callusing or regeneration of plantlet did not occur either with the control treatment of BAP+NAA or BAP+IBA, respectively. All cultures of the germplasm 368572.36 under 4.0 mg/l BAP + 0.05 mg/I NAA formed callus within 11.80 days, whereas, the germplasm 322300.92 under 4.0 mg/I BAP ..... 0.10 mg I l';AA gav e largest callus both in diameter (13.47 mm) and in weight (2667.59 mg) and also growth rate. 0.22 mm/day and 66.69 mg/day, respectively. All the germplasms under 2.0 or 4.0 mg/I BAP and 0.5 or 1.0 mg/I IBA formed maximum 93.33-100.00°-'o shoots in .... .... callus cultures \\ ithin 7.31-11A1 days. Under the above BAP and IBA combinations, the germplasms exhibited >3.0 shooting index and >2 shoots per culture. All the germplasms under the combinations of BAP and IBA attained plant height of >4.0 cm, producing 4-6 leaves per plant, 0.71-1.03 cm internode length, 0.68-0.90 leaf per week and 0.81-0.98 cm/day growth rate. The treatment of BAP singly did not form any root. The other treatments formed roots within the range of 5.2-11.0 days and rooting index varied from 0.33-2.46. The germplasms fanned maximum 3.6 roots per plant under 2.0 mg/l BAP + 1.0 mg/l IBA and maximum length was 4.44 cm in gennplasm 471068.05 under 2.0 mg/l BAP + 0.5 mg/I IBA.