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

Sohrab Davarpanah,Gholamhossein Davarynejad,Mahvash Zarei,Mehdi Aran,Javier Abadía,Ali Tehranifar

doi:10.3390/agronomy10060832

Sohrab Davarpanah, Gholamhossein Davarynejad + Show 4 more

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https://doi.org/10.3390/agronomy10060832

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Abstract

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.

Highlights

Pomegranate (Punica granatum L.; Punicaceae) is a fruit tree grown in a wide range of soils in subtropical and tropical regions, including Mediterranean, Caucasian and Asian countries [1]
Foliar Fe fertilization led to significant increases in leaf Fe concentrations when compared with those in the unfertilized controls, the only exception being the lowest dose of chelate
Foliar fertilization with Fe compounds significantly increased fruit yield in both seasons, with the only exception being the lowest dose of chelate (Table 1)

Summary

Introduction

Pomegranate (Punica granatum L.; Punicaceae) is a fruit tree grown in a wide range of soils in subtropical and tropical regions, including Mediterranean, Caucasian and Asian countries [1]. Fertilizers are crucial for fruit tree production because the plant nutritional status affects vegetative growth, flowering, fruit set and fruit retention and has a marked effect on fruit quality and yield [4,5]. Macronutrients and micronutrients are usually acquired from the soil by roots, but both types of nutrients can be supplied directly to plants via foliar fertilization. This practice minimizes fertilizer and water inputs, and is increasingly used in arid and semiarid regions to correct micronutrient deficiencies [6]. Foliar fertilization has been shown to enhance grain metal contents in cereals [7] and to improve plant nutritional status [8] and fruit set [6] in tree crops. Crop responses to foliar fertilization largely depend on experimental conditions and plant species [6,8]

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