Clonal effect on rooting and acclimation rates for in-vitro micropropagation in hybrid walnut (Juglans x intermedia Mj 209): preliminary observations

The success of walnut ( Juglans sp.) planted forests for timber production have been very variable and genetic material is considered as one of the main drivers (together with site selection and forest management) for the success or failure of the plantations, as the performance of the trees from seed material is very variable. Considering the relevance of this genetic material, several clones have been selected and research have been conducted in order to improve micropropagation procedures. The objective of the present study is to analyze the effects of different clones in the rooting and acclimation rates for in-vitro micropropagation in hybrid walnut ( Juglans x intermedia Mj 209). The results show a significative effect of clones on the rooting and the total micropropagation efficiency rates, but not on the acclimation rate. The efficiency rate of D-117 (65%) is considered statistically higher than the one for D-15 (38%), caused by a higher rooting rate of D-117 (73%) compared with D-15 (55%), because acclimation rate (57%) did not show any clone effect. Considering these differences in the micropropagation success, it might be considered (together with other factors) for clone selection to increase the general performance of the plant production units in large-scale propagation.