Exploring combinations of grafting time and scion cultivar in walnut grafting success under open field condition

Long juvenile period, hard shelled nature of fruit of seed propagated plants, difficulty in grafting and poor success rate has been the major concerns in walnut production in the world. Our study will aid in standardization of suitable techniques for multiplication of high yielding varieties so as to escalate the competitiveness in the international market. Hence, this study was rendered to determine the impact of scion cultivar as well as grafting time in walnut in Jumla district, Nepal in 2021. Hartley and Payne cultivars of walnut together with four disparate grafting dates viz. 14^th March, 21^st March, 28^th March, and 4^th April were employed as treatments and the entire analysis was set down in two factorial randomized complete block design (RCBD). Twenty grafted plants were defined per treatment for the investigation and each treatment were replicated four times. Circumference of ingrafted portion (cm), scion diameter (cm), length of scion (cm), number of leaves per shoot, days to bud burst, grafting success (%), and marketable plants (%) were the parameters measured during the experiment. Our experiment unveiled highly significant influence of cultivar and grafting time on length of scion, number of leaves, days to bud burst, grafting success and marketable plants. Highest scion length (66.03cm) was recorded on 'Payne' while maximum number of leaves (39.75) were observed on 4^th of April and least (32.25) was observed on 14^th March. Significantly earlier bud burst occurred in 'Payne' (55.87 days) whereas 'Hartley' took 61.59 days to bud burst. 'Hartley' variety divulged maximum graft take (81.56%) and marketable plants (75%) whereas least graft take (70.31%) and marketable plants (64.38%) was found in 'Payne' variety. Similarly, highest grafting success (83.13%) and marketable plants (77.50%) were recorded on 4^th April while least graft take (71.25%) and marketable plants (65.63%) were recorded on 21^st March. In a nutshell, 'Hartley' variety uncloaked higher grafting success rate with 4^th April as an ideal grafting time in Jumla district. Thus, grafting on the first week of April using 'Hartley' variety is suggested to the walnut growers and other concerned stakeholders of similar agroclimatic conditions to optimize the graft take rate.