Effects of ethylene inhibitors, silver nitrate (AgNO3), cobalt chloride (CoCl2) and aminooxyacetic acid (AOA), on in vitro shoot induction and rooting of banana (Musa acuminata L.)

Abstract

Significant increase in shoot regeneration, leaf chlorophyll content and rooting occurred when silver nitrate (AgNO₃), cobalt chloride (CoCl₂) or aminooxyacetic acid (AOA) were added to banana culture medium. The highest numbers of shoots per explants shoot length and leaf surface area was obtained when media were supplemented with 10 mgl^-1 AgNO₃. Number of shoots per explants increased three fold, shoot length and leaf surface area increased by an average of 4.5 and 2 cm², respectively, in comparison to control. CoCl₂ and AOA had less promotive effects on shoot generation with maximum shoot number per explant and shoot length achieved at 15 mgl^-1. Rooting of banana shoots in vitro was enhanced by these compounds. The highest number of roots per shoot (21.7) and the longest roots (12.68 cm) were observed when rooting media was supplemented with 10 mgl^-1 AgNO₃. For CoCl₂ and AOA the maximum rooting occurred in media supplemented with 15 mgl^-1, although roots number and root length were lower than those achieved by AgNO₃. Considerable increase in leaf total chlorophyll content occurred in shoots grown on media containing AgNO₃ and AOA. The largest increase in leaf chlorophyll content (120%) was noted when shoots were grown in the presence of 10 mgl^-1 AgNO₃. This was followed by AOA which increased chlorophyll content by 35%. CoCl₂ had no significant effect on leaf chlorophyll content. These findings suggest that application of ethylene inhibitors, particularly AgNO_3, to culture media may be useful for improving in vitro growth performance of banana cultures.