DIFFERENCES IN IRON NUTRITION STRATEGIES OF 2 CALCIFUGES, CAREX-PILULIFERA L. AND VERONICA-OFFICINALIS L

Veronica officinalis and Carex pilulifera, widespread calcifuge plants in Europe, were cultivated in acid and calcareous soils to study diff erences in Fe aquisition strategies indicated in previous studies. The experiments were performed in a computer-controlled glasshouse al a s oil solution moisture content of 50-60 % water holding capacity; addit ional light was supplied at 70 W m(-2) if ambient light was < 100 W m( -2) between 0600 and 1800h. Both species developed chlorosis when grow n in the calcareous soil. C. pilulifera proved unable to translocate s ufficient amounts of Fe to the leaves when cultivated in calcareous so il, but much Fe accumulated in, and especially as a precipitate on the surface of roots. Tn contrast, V. officinalis tended to increase Fe t aken up into the leaves of plants grown on calcareous soil, bur a much greater proportion of the leaf tissue Fe was accumulated as less acti ve forms not extracted by Fe complexing agents, e.g. 1,10-phenanthroli ne, than was the case in acid-soil grown plants. Considerably less Fe was accumulated in the root biomass of V. officinalis compared to C. p ilulifera. It is concluded that chlorosis in C. pilulifera is related to insufficient Fe uptake in the leaves, whereas leaf immobilization o f Fe in physiologically less active forms is the problem in V. officin alis. (C) 1997 Annals of Botany Company.