Study of the Trend of Graft Union Formation in Minigrafting of Walnut (Juglans regia L.)

Walnuts orchards in Iran are not uniform due to sexual propagation. Asexual propagation including minigrafting will lead to uniform orchards and nut production. To study the trend of grafting union formation in walnut some microscopic slides were prepared in different time after 'Serr' cultivar was minigrafted on seedlings. Different stages of grafting process including callus formation and development, necrotic layers deterioration, cambium differentiation and vascular tissues formation in samples were evaluated in 3, 7, 10 weeks; and 6 and 12 months after minigrafting. Results indicated that successful minigraft was observed after 12 months in winter minigrafted seedlings.