Seasonal variability in leaf chemistry of Iris variegata L. genotypes growing in contrasting light conditions

Abstract

During their evolution plants developed a set of mechanisms to adapt to the varying environmental conditions. Light is one of the most dynamic components of the terrestrial environment that affects plant physiology and development. Optimization of light harvesting for photoautotrophic growth inevitably induces specific adjustments in all aspects of plant phenotype: morphology, anatomy, phytochemical composition, flowering phenology etc. As sessile organisms capable of perceiving quantitative and qualitative features of light surroundings, plants need to be particularly plastic in their response to different light environments. For this study genotypes of Iris variegata that occupy different light habitats in Deliblato sands were selected: a) open habitats where they were exposed to full sunlight and b) woodland understories with lower light intensity and changed light quality (vegetative shade). Specimens of those I. variegata genotypes were grown under two experimental light treatments: 1.) high intensity and higher red-far red light ratio and 2.) low intensity and lower red-far red light ratio. Leaves were collected during spring, summer and autumn of one experimental year, dried in silica gel and extracted with methanol. Samples were subjected to UHPLC/qqqMS profiling of phenolics (phenolic acids, flavonoids, and xanthones), and subsequently to chemometric analysis. Results showed that dissimilar light conditions in applied treatments markedly affected I. variegata phenolics composition. Repeated measures model ANOVA revealed a significant effect of seasons for all analyzed phenolics. Concentrations of half of the analyzed chemical compounds were significantly different under two light treatments. The correlations between traits were in almost all cases significant and positive.