Habitat conditions strongly affect macro- and microelement concentrations in Taraxacum microspecies growing on coastal meadows along a soil salinity gradient

Abstract

Wild greens can contribute to the human diet as an important source of essential nutrients and drugs. Since environmental factors, including soil properties, may affect the chemical composition of plants, it is necessary among others to assess various habitats in terms of their usefulness for wild plant harvesting and to study impact of environmental factors on the qualitative and quantitative chemical composition of plants. This study was aimed at (1) examining the mineral composition of leaves of three dandelion microspecies, (2) determining the variability of macro- and microelement concentrations in dandelion leaves from populations growing on salty, brackish and non-saline coastal meadows, and (3) assessing the effects of different habitat conditions on the mineral composition of dandelion leaves. It was hypothesized that dandelion microspecies would differ significantly in the mineral composition of leaves. It was also expected that soil conditions would significantly affect nutrient concentrations in dandelion leaves, with soil salinity being the most important factor that differentiated studied populations. Leaves of three dandelion microspecies (Taraxacum balticum, T. nordstedtii, T. haematicum) were harvested in Baltic costal grasslands, along the soil salinity gradient, to determine macro- and microelement concentrations. Soil samples collected in the closest vicinity of the harvested plants showed the study sites to differ significantly in their soil properties. Moderately saline and organic soils, rich in potassium (K), magnesium (Mg), and calcium (Ca), supported T. balticum. Moderately or weakly saline and non-saline, organic or mineral soils, with lower median values of K, Mg, and Ca, were typical of T. nordstedtii sites, while the lowest median values of all the soil properties studied were found for T. haematicum sites. Our results proved that dandelion microspecies differ significantly in the mineral composition of their leaves. The between-microspecies differences were significant for all the macroelements except magnesium and all the microelements except molybdenum. Most of the macro- and microelements in leaves of the dandelion microspecies correlated positively and significantly with the soil properties, the strongest correlations being found for soil salinity and the leaf Na, Mn, Ca, Fe, K and Zn contents, followed by soil pH and the leaf Na, Mn, Fe, K, Ca, Zn and Mg. Moreover, the impact of soil properties on the mineral contents in leaves of the dandelions we examined seems to be stronger than the genetic differences between dandelion microspecies. Results of our studies on mineral composition of dandelion leaves lend support to the contention that wild greens provide essential mineral nutrients to the diet. Coastal meadows, fed by the brackish water of the Baltic Sea and free of anthropogenic pollution, are a good habitat to collect wild greens from.