Study on the new vegetative propagation method 'epicotyl grafting' in walnut trees (Juglans spp.).

摘要

Because walnut tree is difficult to graft and induce rooting, the epicotyl grafting technique was studied. Seeds of Mandshurica walnut (Juglans mandshurica) or Persian walnut (J. regia) were sown and seedlings were grafted from 5 to 10 days after its germination. Scions which contained one or two buds were cut from 3 to 6 cm. The seedlings were cut from 2 to 4 cm in height from the ground, and then the centre of cut section was conducted with cleft grafting method. Finally, they were fixed with plastic clamp. After grafting, each of the grafts was covered with polyvinyl envelope to protect against drying, and then kept at 25-27 degrees C and 80-85% humidity. After ~10 days, its buds started to burst. If the grafts would be grown from 3 to 5 cm, the envelope must be removed. Finally, if the seedling grew well in pots, and if it increased the external temperature, the grafts must be translocated to a nursery and be managed intensively. The survival rate was 65-87.5% according to grafting time. The rate in February was greater than that in March and April. In addition, the total average survival rate was 78.9%. But the rate in April was lower than the others as well as was not significant, statistically. Three cultivars, i.e. Yongdong, Sinnou and McKinster, were grafted each to 360 trees according to the sampled parts and varieties. The average rates within varieties were investigated in terminal and middle part, 85.5% and 78.4%, respectively, and the former part was measured to be superior to the latter. But only one scion could be sampled in the terminal part, on the other hand, several scion in the middle part. The survival rate of Yongdong, the new variety in Korea, was 76.4 and 68.9%, in terminal and middle part, respectively. In addition, the rate of Sinnou was 90.8 and 90.3%, and the rate of McKinster was 89.2 and 76.1%, respectively. Therefore, McKinster, a variety in the USA, was more excellent than the others in the survival rate..