Differences in omega-6/omega-3 ratio and polyunsaturated fatty acid content in five Iranian walnuts (Juglans regia) cultivars - TOOTOONCHI, AMIR SASAN; DOOSTI, MAHMOOD; ABDI, KHOSROU; AMIN, GHOLAMREZA; GOODARZI, MOHAMMAD TAGHI (The Indian Journal of Agricultural Sciences, 2013)