Effectiveness of synthetic calcite doped with Fe-EDDHSA as a slow-release Fe source: In-vitro experiment on kiwifruit (Actinidia chinensis var. deliciosa) plants

Doped calcite (Fe-EDDHSA/CaCO3) was experimentally produced. The hypothesis of the present experiment is that, when roots get in contact with Fe-EDDHSA/CaCO3, the extrusion of H+ decreases the pH and dissolves calcite with subsequent release of Fe that becomes available for roots. The aim of the experiment was to determine whether doped calcite might represent a slow-release Fe source for in-vitro grown kiwifruit plantlets. The root elongation media used in the experiment had pH 8.0 and differed from each other for Fe supply as follow: Control medium that contained complete Murashige and Skoog salt mixture, including FeSO4 and Na(2)EDTA; calcite medium enriched with Fe-EDDHSA/CaCO3 as the only Fe source; -Fe medium without Fe. The absence of FeSO4 in the medium caused a reduction of plantlet growth. The final pH was higher with calcite medium than in control and -Fe. The addition of Fe-EDDHSA/CaCO3 increased Fe shoot concentration when compared with the -Fe medium. The data of the present experiment show the potential Fe slow release ability of Fe-EDDHSA/CaCO3; however, further investigation on Fe containing fertilizers should be conducted on potted plants to validate our results