Inhaltszusammenfassung

Soil and leaf samples were taken from microsites of green and chlorotic pedunculate oaks (Quercus robur L.) growing at the sun-exposed margins of four stands on calcareous soils in the region of Gottingen (Lower Saxony, Germany). The chlorotic leaves exhibited typical symptoms of Fe/Mn deficiency. The Mn concentrations of the soil were low but significant differences between the microsites of green and chlorotic trees were not detected. Significant correlations were found between the foliar M...Soil and leaf samples were taken from microsites of green and chlorotic pedunculate oaks (Quercus robur L.) growing at the sun-exposed margins of four stands on calcareous soils in the region of Gottingen (Lower Saxony, Germany). The chlorotic leaves exhibited typical symptoms of Fe/Mn deficiency. The Mn concentrations of the soil were low but significant differences between the microsites of green and chlorotic trees were not detected. Significant correlations were found between the foliar Mn concentrations (dependent variable) and the fractions of Mn in both total exchangeable cations of the soil and total cations of the soil equilibrium solution (independent variables). The chlorotic leaves exhibited lower concentrations of Mn and 'active iron', but elevated Ca/Mn ratios and higher concentrations of ascorbate. Light-microscopic investigations did not reveal phloem damages to the petioles, and the starch concentrations of green and chlorotic leaves did not differ significantly. We conclude that the observed chlorosis is caused by lime-induced Mn deficiency, enhanced by a short supply of (physiologically active) Fe. Thus, the chlorosis syndrome can be explained satisfactorily by site factors without involving hypotheses based on the action of pathogens.» weiterlesen» einklappen

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Klassifikation

DFG Fachgebiet:
Pflanzenwissenschaften

DDC Sachgruppe:
Biowissenschaften, Biologie