Persian walnut (Juglans regia L.) is a nutritionally rich and also popular nut which is largely consumed throughout the world. Since ancient times, it has been used in folk medicine for treatment of several diseases and disorders such as diabetes, cancer, skin disease and infections, rheumatoid arthritis. Persian walnut (Juglans regia L.) is one of the main nut crops in Iran. Walnut together with pistachio and almond have covered more than 800,000 ha (28.5 %) of Iran’s orchards. After pistachio, walnut is the second important nut crop in term of production.