Iron Deficiency Chlorosis of Kiwi Trees (Actinidia deliciosa) as Affected by Soil Injection of Ferrous Sulfate, Sulfuric Acid and Organic Matter

For controlling iron deficiency of kiwi trees، a completely randomized block design experiment was conducted during 2012 and 2013 in Mazandaran، north of Iran. The experiment contained three types of soil injection: 1- iron sulfate (Fe0=0، Fe1=1 and Fe2=2 kg per tree)، 2- sulfuric acid (AS0=0، AS1=1 and AS2=2 L per tree)، and 3- organic matter (OM0=0، OM1=2 and OM2=4 kg per tree). These treatments were carried out early in 2012 and compared with fertigation of iron chelate (100 gr of Fe-EDDHA each year per tree). Biennial results showed that Fe2AS1OM2 caused the highest fruit yield and the largest leaf area. The highest leaf chlorophyll index (SPAD reading) was observed in Fe2AS2OM2. Single fruit weight and size were highest in Fe1AS2OM2. Soil injection of ferrous sulfate and sulfuric acid increased iron concentration in leaves، but organic matter had no such effect. Applying sulfuric acid also decreased phosphorus concentration in leaves. In conclusion، results of this two-year experiment confirmed superior benefits of soil injection of 2 kg of iron sulfate، 0. 5 L of sulfuric acid، and 4 kg of organic matter per tree، compared to iron chelate application، in kiwi orchards.