Prevention of Iron‐Deficiency Induced Chlorosis in Kiwifruit (Actinidia deliciosa) Through Soil Application of Synthetic Vivianite in a Calcareous Soil

Abstract

In this study we have tested the hypothesis that lime‐induced Fe deficiency chlorosis of kiwifruit may be prevented by the application of a synthetic iron(II)‐phosphate analogous to the mineral vivianite [(Fe₃(PO₄)₂·8H₂O)]. Two experiments, under greenhouse and field conditions, were performed. In the greenhouse, 1‐year old micropropagated plants (Actinidia deliciosa, cv. Hayward), grown in 3‐L pots on a calcareous soil, were treated in early autumn with soil‐applied: (1) synthetic vivianite (1.35 g plant⁻¹) and (2) Fe‐EDDHA (24 mg Fe plant⁻¹). The synthetic vivianite suspension, prepared by dissolving ferrous sulfate and mono‐ammonium phosphate, was injected into the soil as a sole application whereas the Fe‐EDDHA solution was applied four times at weekly intervals. The field experiment was conducted in a mature drip‐irrigated kiwifruit orchard located on a calcareous soil in the Eastern Po Valley (Italy). Treatments were performed in early autumn by injecting synthetic vivianite (1.8 kg tree⁻¹) and Fe‐EDDHA (600 mg Fe tree⁻¹) into four holes in the soil around each tree, at a depth of 25–30 cm. The Fe‐chelate application was repeated at the same rate in the following spring. Untreated (control) plants were used in both experiments. Autumn‐applied Fe fertilisers significantly prevented development of Fe chlorosis under greenhouse conditions whereas in the field only vivianite was effective. In conclusion, these 1‐year results show that vivianite represents an effective alternative to soil‐applied Fe chelates for preventing Fe chlorosis in kiwifruit orchards.

Keywords:

• Kiwifruit
• Fe chlorosis
• Vivianite
• Fe‐chelate
• Calcareous soil

Acknowledgments

We greatly thank the Graziani farm (Via Formellino 3, Faenza, Italy) and the PEMPA (Faenza, Italy) grower association for their valuable cooperation in the field experiment.