Intrapopulational variability and biochemistry of the globally rare species Coleanthus subtilis in response to the sediment parameters

Abstract

Aims Coleanthus subtilis is a globally rare or threatened, ephemeral therophyte of exposed bottoms of water reservoirs and riverbanks. Nevertheless, it shows a potential to conquer new areas and dominate in phytocoenoses showing morphological differentiation. The main aim of the study was to reveal the intrapopulational variability of the species in relation to sediment characteristics, ecological preferences in microscale, and allelopathic potential in the context of biochemical composition of its biomass. Methods A fishpond with a stable population was selected and data were collected from 107 plots distributed in transects perpendicular to the pond banks; in each plot following parameters were determined: pH, macroelement content in sediments, morphotypes of C. subtilis specimens, species composition of vegetation patches, and ecological indicator values. Collected specimens were used to determine the chemical composition and ecotoxicity. Results Morphological variability of C. subtilis is determined by pH and macroelement content of the sediments. Those parameters and values of ecological indicators (moisture, temperature and light) show a link to the composition of vegetation patches and the phytocoenoses with the high abundance of C. subtilis. Capability of C. subtilis to inhibit germination and growth of other species may account for its prevalence in phytocoenoses. Benzoxazinone derivatives, phenolic compounds and carboxylic acids known to be allelochemicals were identified in the species. Conclusions Morphological variability of C. subtilis is controlled by pH and nutrient content in sediments and species composition of vegetation patches; allelopathic effect found experimentally may be conditioned by chemical compounds determined in its specimens.