Effects of Different Culture Media Compositions on In Vitro Micropropagation from Paradox Walnut Rootstock Nodes

The aim of this study is to establish an effective protocol for in vitro micropropagation from node explants of the 'Paradox' (Juglans regia x J. hindsii) rootstock. In the first stage of the study, the node explants were cultured in semi-solid media after being exposed to different sterilization methods. The most effective sterilization method was observed as ST2 with the lowest darkening rate (4 %). According to the results, SP4 medium provided the highest number of shoots per unit explant (1.05 shoots/explant) and 100 % shoot formation, SP2 medium provided the best mean shoot length (1.6 cm) and the mean number of nodes per unit explant (7.95 nodes/explant). Best root induction was provided from ½ Modified MS medium containing 4 mg/L IBA with 30 g/L sucrose. For root induction explants were retained under dark conditions for 7 days at 24±2oC. In order to ensure root formation and elongation, shoot explants with root induction cultured in a 16-hour photoperiod (3500 lux) for 21 days in different nutrient media containing 2.4 mg/L Gelrite, hormone-free and mixed with vermiculite (1:1 v/v) and was rooting rate is 45.45 % in ¼DFe medium.