Effect of Fructose on Growth of Papaw Shoot Explants in vitro

Abstract

The effects on papaw (Carica papaya L.) shoot growth of the carbohydrates sucrose, fructose, glucose and ribose singly and combined, were compared at a range of concentrations, in both autoclaved and filtered media. Fructose (10 g L^-1), when autoclaved together with other media components, consistently promoted growth of shoots from buds on nodal sections or buds excised with a wedge of stem tissue. This enhancement was seen if the fructose was used singly or in combination with 10 g L^-1 sucrose. By contrast, autoclaved media containing fructose reduced growth of small axillary bud explants. Decreasing the pH of fructose solution from 5.8 to 4.4 before autoclaving enhanced growth of buds from nodal sections. Other sugars in the D-ketose group inhibited papaw shoot growth totally when autoclaved with other media components. A radish cotyledon bioassay of solutions of fructose autoclaved singly or with NH₄NO₃ (20 mM) showed no evidence of cytokinin effects.