REPEATED MEASURES ANALYSIS OF CHANGES IN PHOTOSYNTHETIC EFFICIENCY IN SOUR CHERRY DURING WATER DEFICIT

The objective of this study was to investigate changes in photosynthetic efficiency applying repeated measures ANOVA using the photosynthetic performance index (PIABS) of the JIP-test as a vitality parameter in seven genotypes of sour cherry (Prunus cerasus, L.) during 10 days of continuous water deficit. Both univariate and multivariate ANOVA repeated measures revealed highly significant time effect (Days) and its subsequent interactions with genotype and water deficit. However, the multivariate Pillai’s trace test detected the interaction Time × Genotype × Water deficit as not significant. According to the Tukey’s Studentized Range (HSD) test, differences between the control and genotypes exposed to water stress became significant on the fourth day of the experiment, indicating that the plants on the average, began to lose their photosynthetic efficiency four days after being exposed to water shortage. It corroborates previous findings in other species that PIABS is very sensitive tool for detecting drought stress.