Melatonin Effect (IMAGE) University of Copenhagen - Faculty of Science Caption Interactive effects of melatonin and abscisic acid (ABA) on dark-adapted image of maximum quantum efficiency of photosystem II (FV/FM) for top leaf of four-leaf stage seedling under cold stress barley var. Steptoe. The four-leaf stage seedlings were pretreated with 1 mM melatonin (MT), 1.5 mM ABA (ABA), 1.5 mM ABA + 1 mM melatonin (ABA + MT), 10 mM fluridone + 1 mM melatonin (FLU + MT), or distilled water (Mock), and were exposed to a 48-hour cold (2±0.5°C). The dark-adapted images of FV/FM were monitored to evaluate the cold tolerance. Credit Fulai Liu, University of Copenhagen Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.