The diversity of iron acquisition strategies of calcifuge plant species from dry acidic grasslands

Although the calcifuge plant species existing in dry acidic grasslands are believed to be prone to iron (Fe) -dependent limitations, little is known about their susceptibility and reaction to pH-dependent Fe starvation. Therefore, the present study examines the effects of contrasting soils (acidic Podzol vs alkaline Rendzina) and Fe supplementation (Fe-HBED) on alkaline substratum (5 and 25 mu mol Fe-HBED kg-1 soil). Five calcifuge dicoty-ledonous plant species (Alyssum montanum L., Antennaria dioica (L.) Gaertn., Hypochaeris radicata L., Jasione montana L. and Potentilla arenaria Borkh.) were tested in a pot experiment under field conditions. Chlorosis, chlorophyll content, growth and chlorophyll a fluorescence were measured. The elemental composition (contents of Ca, Mg, Fe, Mn, Zn and Cu) of the roots and shoots were analyzed, as well as their specialized metabolites. Two studied species (A. dioica d and J. montana) were susceptible to pH-dependent chlorosis, and this deficiency was successfully diminished by the application of Fe-HBED. Almost all the studied species (except A. montanum) preferred the acidic soil. Fe-HBED treatments were not sufficient for supporting the growth of H. radicata and J. montana in alkaline soil to the same degree as in acidic soil, which suggests additional non-Fe-dependent limitations. Both Fe starvation and Fe over-supplementation caused species-specific changes in chlorophyll a fluorescence. The disturbed Fe acquisition in the alkaline soil was not the sole source of the observed limitations, as the chlorosis-susceptible species demonstrated a complex interaction between Fe, Mn and Zn. The species resistant to lime chlorosis contained greater amounts of specialized metabolites than the susceptible plants. Our findings do not support hypothesis that all calcifuges are susceptible to Fe-dependent chlorosis: calcifuge plant species from dry acidic grasslands appear to have diverse Fe requirements and acquisition strategies.

Automated summary

This study examines the susceptibility and reaction of calcifuge plant species in dry acidic grasslands to pH-dependent iron (Fe) starvation. It finds that some plants are sensitive to pH-dependent chlorosis, and this deficiency can be reduced by Fe supplementation. The preference for acidic soil varies among different plants, and Fe-HBED treatments in alkaline soil may not support growth as effectively as in acidic soil. Overall, calcifuge plant species from dry acidic grasslands have diverse susceptibility to Fe-dependent chlorosis and different Fe requirements and acquisition strategies.