APICAL DOMINANCE BRAKE BY PHYSICAL PROCESSES ON BANANA IN VITRO CULTURE

Abstract

Several physical processes were evaluated for apical dominance brake of banana (Musa AAB cv. Maçã) initial explants. The treatments were: 1. whole explant subculture; 2. explants divided in two; 3. explants divided in four parts; and 4. explants superficially cut three times (star), rhizome base maintained intact. MS media were supplemented with NaH₂PO₄ 170 mg L^-1), adenine (40 mg L^-1), BAP (1.5 mg L^-1) and Kin (3.5 mg L^-1). After 80 days, explants originated from these treatments were subcultured in modified MS media, similar to the first, except for growth regulators BAP (2.3 mg L^-1) and AIA (0.18 mg L^-1). All treatments produced a linear increase on shoot number during the first 80 days, although losses due to oxidation and/or contamination were higher when initial explants were divided in two and four parts. Shoot production at 80 days showed no significant differences among treatments, while after six subcultures (164 days), explants divided in two parts produced more shoots. All treatments showed a decreasing tendency for multiplication rate.

KEY-WORDS: Tissue culture; micropropagation; Musa AAB.