Fruit Growing Institute, BG – 4000 Plovdiv, Bulgaria
GANDEV, S., 2009. Propagation of walnut (Juglans regia L.) under controlled temperature by the methods of omega bench grafting, hot callus and epicotyl grafting. Bulg. J. Agric. Sci., 15: 105-108
The basic way for walnut propagation in Bulgaria is the Patch budding method. The grafted plants are grown in the open in the nursery and during years with low winter temperatures or spring frosts the survival rate is low. The aim of the experiment was to study and compare different methods of walnut propagation, in which the grafting success does not depend on the external climatic conditions. The investigation was carried out in 2006-2007 with cultivar ‘Izvor 10’ grafted on common walnut rootstock (Juglans regia L.). In the two years of the experiment at the end of March the tested grafted plants were placed under controlled temperature of 27° C for callus formation. Four weeks after grafting the plants were transferred to a room temperature of 15-18° C for twenty days, after which the percentage of graft take was recorded. The lowest percentage of successfully grafted plants was reported for the classical Omega bench grafting method (control) – 40.8 % in both years of the experiment. For the new propagation techniques, close percentages of successfully grafted plants were obtained – 74.2 % in average for the method of Hot callus and 77.5 % for the method of Epicotyl grafting. As a conclusion, the use of the new methods of walnut propagation – Hot callus and Epicotyl grafting – increased the percentage of the successfully grafted plants in the period of winter dormancy under controlled temperature.