Walnut grafting success as affected by stratification.

The effect of air temperature and relative humidity inside a stratification room on walnut grafting success was investigated in this study. The whip-and-tongue grafting technique was used. One-year-old seedlings of local types of walnut (Juglans regia L.) and five cultivars and selections, including cv. Seinovo (control), Ovcar, G-286, Elit and G-139 were used for grafting. Three stratification treatments were employed. The air temperature inside the stratification room in 2003 and 2004 ranged from 26-28°C and 28-29°C respectively. As for relative humidity, the values measured in both 2003 and 2004 were within the 60-70% range. The average percent graft take was 70.0% in 2003 and 83.4% in 2004. The highest average graft success of 86.0% in both years in all the tested cultivars and selections was obtained with the treatment involving dipping scions and graft unions into paraffin, stratification in sawdust up to the union and covering with polyethylene foil. Among the cultivars and selections tested, the graft-take success was highest in cv. Seinovo (87.7%) and lowest in selection G-139 (67.9%).