Duckweeds are the model organisms in plant physiology, ecology, ecotoxicology, ecophysiology and are sensitive to various stressful environmental conditions such as heavy metal stress, thermal or heat stress, drought, high salinity, extremely low or high temperature. Abscisic acid is a stress hormone in plants involved in seed dormancy the effect of ABA was tested on two different Spirodela polyrhiza ecotypes (in terms of turion production) in 7-day tests. ABA in larger concentrations induced growth retardation and growth inhibition in both clones. Both clones showed high turion yields (40-60%). Effective concentrations of abscisic acid resulting in 50% growth inhibition (EC50) of the two clones approached 0.1 μmol with a slightly higher value for Clone 2. From time-dose experiments, Clone 2 exhibited slower growth. In correlation to dry matter content, ABA-induced turions and semi-turions of Clone 1 exhibited 2-4 times higher DMC % than the respective fronds in a given treatment between 0.25 and 1 μmol ABA. External ABA-induced significant accumulation of starch in fronds with the highest extent at 1 μmol ABA more significantly in Clone 2.