Early Season Foliar Iron Fertilization Increases Fruit Yield and Quality in Pomegranate

© 2020 by the authors.Early season foliar fertilization with different nutrients is a promising tool in pomegranate grown in poor, high pH soils. The effects of foliar fertilization with FeSO4 and the synthetic chelate Fe(III)-EDDHA (Fe(III)-ethylendiaminedi(o-hydroxyphenylacetate)) on fruit yield and physicochemical characteristics were assessed in a two-season field trial. Fertilizers were sprayed at full bloom and one month later, using Fe concentrations of 1.3 and 2.6 mM for FeSO4 and 1.1 and 2.1 mM for the Fe-chelate. Both doses of FeSO4 and the higher chelate dose increased leaf Fe concentrations and fruit yield, with the best results being observed with 2.6 mM FeSO4 (20–31% increases in yield). On the other hand, leaf N, P, K, Ca, and Mn concentrations were not affected by foliar Fe fertilization. The only treatment that increased the number of fruits per tree, aril juice content and juice total soluble solids and decreased juice total acidity in both seasons was 2.6 mM FeSO4. Both FeSO4 doses caused consistent increases in the maturity index and total sugars in juice, along with minor decreases in juice total phenolic compounds. The antioxidant activity in juice was slightly decreased by 2.6 mM FeSO4. In conclusion, early season foliar Fe fertilization had positive effects on pomegranate yield and quality, with FeSO4 being better than Fe(III)-EDDHA.The study was funded by the Ferdowsi University of Mashhad (code: 3/32199). J.A. was partially supported by the Spanish State Research Agency (AEI) co-financed by the European Regional Development Fund (FEDER) (project AGL2016-75226-R; AEI/FEDER, UE) and the Aragón Government (group A09-20R).Peer reviewe