FACTORS AFFECTING ABSCISSION IN SPIRODELA OLIGORHIZA (LEMNACEAE): II. SUCROSE

0.1 M and 0.2 M sucrose do not induce abscission and significantly reduce abscission induced by ultraviolet radiation whereas higher concentrations (0.4 M) induce abscission even without UV radiation. The effect of different concentrations of sucrose on endogenous ABA levels and on ethylene release suggest that sucrose‐induced abscission occurs when ethylene release is accompanied by a rise in the endogenous ABA level. When plants are floated on low concentrations of ABA (0.1 ppm), they release a considerable amount of ethylene but do not abscise. On higher concentrations of ABA (10 ppm), they abscise, even though ethylene release is lower.