Pestana, M.Gama, FlorindaSaavedra, TeresaVarennes, Amarilis deCorreia, P. J.2012-04-192012-04-192012Pestana, M.; Gama, F. The root ferric-chelate reductase of Ceratonia siliqua (L.) and Poncirus trifoliata (L.) Raf. responds differently to a low level of iron. Scientia Horticulturae, 135, 1, 65-67, 2012.03044238AU: PCO01134;http://hdl.handle.net/10400.1/1061Iron (Fe) deficiency is a common nutritional disorder in several crops grown in calcareous soils, but some species are well adapted to these conditions. A hydroponic experiment was conducted to compare the response of a calcicole species Ceratonia siliqua L. (carob) and of Poncirus trifoliata (L.) Raf., a citrus rootstock very sensitive to Fe deficiency. Rootstocks from both species were grown in nutrient solutions without Fe (0 M Fe), with 1 M Fe, and with 10 M Fe (carob) or 40 M Fe (P. trifoliata). A low level of Fe or its absence in the nutrient solution led to a significant decrease in P. trifoliata vegetative growth and in SPAD readings. The root activity of ferric-chelate reductase (FC-R), a key enzyme in Fe uptake, was low in the absence or with high levels of Fe. Its highest values were in roots exposed to a low level of Fe as described in several sensitive species. In contrast, the activity of FC-R was very high in carob in the absence of Fe and was decreased sharply even when only a low level of Fe was present in the nutrient solution. Plant growth and SPAD readings in the leaves of carob were similar in all treatments. Carob seems to maintain a large activity of root FC-R that may ensure enough Fe to satisfy plant demand. The fact that it presents a slow growing pattern may also contribute to the tolerance of this species to low levels of external Fe.engCarob-treeCitrusHydroponicsMicronutrientRelative growth rateRootstocksjournal article2012-03-14