On-uma Boonmee and Somchai Chuan-udom

pp. 219 - 228

Abstract

Two types of cytokinins, 6-Benzyladenine (BA) and/or coconut water (CW) and pH of medium were studied for their effects on shoot formation, growth and somaclonal variation of banana tissue culture. The cultures were carried out on Murashige and Skoog (MS) medium for 30 days. The average shoot length (5.82
cm) was obtained in liquid medium supplemented with 15% CW. While a high number of shoots at 3.8 shoots/explant were obtained in liquid medium supplemented with 5 mg/l BA. For fresh weight, liquid medium supplemented with 5 mg/l BA in combination with 15% CW gave the best results (2.26 g/shoot). An optimum pH for promotion shoot length (5.67 cm) was 5.6 whereas the lower value (pH 4) promoted a high number of shoot formation (3.89 shoots/explant). The highest fresh weight of 1.33 g/shoot was obtained on medium adjusted pH to 8. After maintaining the shoots by successive subculturing (3-4 week-intervals) on MS medium with 5 mg/l BA several morphological abnormalities were obtained. Among those, chlorotic
leaves (1.5%) were firstly observed in the first subculture and increased to 3% in the second subculture. Moreover, a narrow leaf at 25.76% was also observed in this period. Further subculture, more somaclonal variation, such as a thin long shoots, nodular shoots and bamboo-like leaf, appeared. Isozyme marker
revealed a difference in zymogram patterns among those somaclonal variants.