Improving the bud take rate in conventional patch budding of Persian walnut by applying a paste of the DKW semi-solid medium enriched with plant growth regulators

Low bud take rate is an important barrier to successful clonal propagation of Persian walnut (Juglans regia) in Iran. In this study, inspired from the treatments used in in-vitro propagation of walnut, we developed some semi-solid treatments based on the DKW medium to which growth regulators and antioxidants were added. The experiment was conducted with 11 treatments and 17 replications. The scion was Z60 genotype, which was patch budded on two-year-old trees raised from seeds of local walnut (J. regia). The effect of experimental treatment on bud-take rate, number of nodes, scion diameter and length were observed after one and tree months after budding. The bud take rate was influenced significantly by applied treatments. The treated buds with DKW semi-solid medium containing 5 µM BA and 57 µM ascorbic acid showed higher bud take rate (82%) which was not considered significant from that of control (59%) after one month. However, in the second observation which was done after three months from budding the same treatment still kept a high bud take (71%), which was considered significantly more than that of the control treatment (24%). The scion diameter was the other trait that was significantly increased by the DKW semi-solid medium containing 10 µM BA and 57 µM ascorbic acid (6.2 vs. 5.3 mm in the control). The results show viability of this approach as a tool for improvement of bud take rate in Persian walnut and possibly other orthodox plants.