evaluation of topworking methods and times in persian walnut trees in west azerbaijan conditions

walnut is one of the most important nut crops in iran. in order to achieve an appropriate and economical production of old seedling orchards of this product, the only fastest and most cost-effective possible option for improving seedling trees is graft operation through top-working using the new improved cultivars in the world. this study was conducted as a  factorial experiment in a randomized complete blocks design under west azerbaijan conditions, with the aims of determine the best time for grafting during april and may 2011-2012 season and doing a modified side grafting method and compare it with the bark grafting. for this purpose, two superior ‘pedro’ and ‘chandler’ walnut cultivars were used as scions to achieve a high percentage of graft take. the results showed that the highest percent of graft-take was related to the modified side grafting method with the highest rates of graft survival (97.32 percent) and final graft-take (83.93 percent), that was better than bark grafting in in top-working of walnut trees. also, regarding the grafting time, the highest percent of graft-take was obtained from may with the highest rates of graft survival (98.95 percent) and final graft-take (89.49 percent), that was higher than april.