Response to waterlogging and differing sensitivity to divalent iron and manganese in clones of Dactylis glomerata L. derived from well-drained and poorly-drained soils

Clonally propagated plants of Dactylis glomerata derived from a well-drained, heavily grazed cliff habitat (clone L) and from an undergrazed poorly-drained soil (clone A) were tested for waterlogging tolerance in soil-culture. Water-logging did not affect the two clones differentially, a result, which contrasted strongly with that of a previous experiment in which simulated grazing (clipping to 20 cm) unexpectedly caused clone A to be less tolerant of waterlogging than clone L. Maximum leaf and leaf sheath length was reduced more by water-logging in clone L than in clone A (P < 0.05). In solution-culture when provided with factorial combinations of 0.5, 5 and 50 mg dm−2 of Fe2+ and Mn2+ the shoot dry weight yield of the dry-soil clone was reduced more than that of the wet-soil clone by 50 mg Fe dm−3 irrespective of Mn2+ concentration (P < 0.01) but the reduction of growth was less at higher Mn2+ concentrations. Fifty milligrams of Mn2+ dm−3 reduced the growth of the dry soil clone but increased the growth of the wet soil clone with Fe2+ at 5 mg dm−2 (P < 0.05). Iron at 0.5 mg dm−2 was suboptimal for shoot growth of both clones at any level of Mn2+ and caused more severe leaf chlorosis in the wet soil clone. Leaf tissue of clone L contained more iron than that of clone A after waterlogging (P < 0.01) but in solution culture, though increasing iron from 0.5 to 50 mg dm−3 almost doubled leaf iron content (P < 0.001), the interaction Clones × Mn × Fe just failed to reach significance at P < 0.05. The manganese content of leaf tissue from the two clones varied differently in response to solution manganese (Clones × Mn P < 0.01), clone A showing a slightly greater increase of manganese content at high solution concentration. Iron at 50 mg dm−3 suppressed Mn uptake (Mn × Fe, P < 0.001) in both clones. The two clones thus show marked environmental adaptation to the chemistry of wet and dry soils.