The Relationship Between Environmental Factors and Rootstock Growth Stage with Graft Success in Walnut

Abstract

The aim of this study was to determine the influence of environmental factors and rootstock growth stage on graft success. The experiment was conducted during 2012 and 2013 at the Black Sea Agricultural Research Institute of Samsun, Turkey. The whip-and-tongue method was used to graft 'Chandler' (J. regia) scion wood onto one-yr-old English walnut seedlings (Juglans regia L.). A factorial experiment with two years, two nursery conditions (open field and greenhouse with 50% shade) and four grafting times (15 March, 5 April, 25 April and 15 May) was performed to evaluate factors affecting grafting success. Graft success ranged from 18.3 to 100 % depending on nursery conditions, grafting time and year. Best graft success was obtained between the period of bud burst and about 15 cm shoot growth of rootstocks. Depending on the year, graft success was negatively correlated with minimum and mean temperature (p<0.01). The growth level of rootstocks was a useful indicator to initiate grafting for walnut under outdoor conditions.