Micropropagation of walnut (Juglans regia L.)

The objective of this work was to establish regeneration protocol for walnut (Juglans regia L.) by multiplication of shoots from axillary buds. Different concentrations of TDZ (0.0, 1.0, 2.5, 5.0 mg/l), IBA (0.0, 1.0, 2.5, 5.0 mg/l) or IBA together with TDZ were investigated to optimize regeneration for the multiplication in the NGE (Sanchez) culture medium. Multiplication rate increased with increased concentration of TDZ or IBA together with TDZ. The highest mean multiplication rate was observed in the fourth subculture with 2.5 mg/l TDZ + 2.5 mg/l IBA reaching 5.33 shoots per explant. The shoots supplemented with 5 mg/l IBA (62.71%) had higher number of rooted shoots than those supplemented with 2.5 mg/l IBA (45.66%). With 73.24% of rooting, the shoots rooted on medium containing 2.5 mg/l IBA after etiolation application had higher number of rooted shoots than those supplemented with 5 mg/l IBA with 64.69% of rooting after etiolation application. The highest mean survival rate of the shoots was observed in 2.5 mg/l TDZ + 2.5 mg/l IBA reaching 35.27%. Results showed that walnut in vitro micropropagation is feasible and the best growth percentage was obtained in 5.0 mg/l TDZ, and 2.5 mg/l TDZ with 2.5 mg/l IBA.