ISHS Acta Horticulturae 636: XXVI International Horticultural Congress: Key Processes in the Growth and Cropping of Deciduous Fruit and Nut Trees
INVESTIGATING THE INFLUENCES OF SCION BUDS ON WALNUT IN SITU GRAFTING BY FEEDING 32P |
| Authors: | Y. Zhang, G. Li, W. Liu, T. Gao |
| Keywords: | Juglans regia, grafting union, new shoot growth, radioactive labeling, rootstock |
| Abstract:
‘Shan-1’, a cultivar of walnut (Juglans regia L.), was used to study the effects of scion buds on the uniting process of walnut in situ grafting by an isotopic tracing technique. 32P was fed to the root systems of rootstocks. The grafting method used was whip and tongue. There were four treatments of scion buds: two-bud scions, upper-bud scions, lower-bud scions and no-bud scions. The dynamic curves of 32P movement in the new shoots indicated that scion buds affected the healing process of graft unions significantly. The number of buds on a scion and the distance of scion bud from the graft union had great influences on the early healing at the graft union and scion bud emergence. Comparing the four treatments, 32P was detected earliest in the two-bud scions, and then the upper-bud scions and finally lower-bud scions; no 32P was detected in the no-bud scions. The results indicated that the earliest rootstock-scion unison occurred in the two-bud scions. The distance of the scion bud from the grafting union influenced rootstock-scion unison and new shoot growth. The two new shoots emerging on the two-bud scions showed different growth dynamics. The upper shoot grew faster than the lower shoot up to 80 days after emerging. After that, the growth of the lower shoot gradually increased, strengthened, and became dominant eventually. Although there were differences between two-bud scions and single-bud scions, the survival rate of grafting was not influenced, indicating that single-bud scions could be used in walnut in situ grafting. For single-bud scions, bud proximity to the graft union did not influence grafting success, although the speed of union healing varied. The practical significance of single-bud scion grafting is discussed with respect to the serious problem of the short supply of scionwood for walnut propagation. | |
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