THEORY AND PRACTICE OF WALNUT GRAFTING

Walnut (Juglans regia L.) is the fruit tree distributed widely in the world, which is also one with long history, wide cultivation and very important dry-fruit and oil-yielding trees in China.
On the study of grafting technique, it has made an encouraging progress both at home and abroad in recent years.
But the problem that the grafting survival percentage of walnut is lower and not stable hasn’t been solved up to now, which hindered the advancement of good varieties, regional assignment and marketibility of walnut production directly.
Therefore, it is extremely urgent to explore the main factors affecting the survival of walnut grafting, to fine the grafting technique and to solve the problem that the survival percentage of walnut grafting is lower.
On the main factors affecting the survival of walnut grafting, there were two main opinions as follows: (1)The xylem bleeding was the main factor affecting walnut grafting.
Prativiera (1983)² considered that was due to the exist of juglone in the bleeding, which was harmful to the growth of walnut callus.
But Zhu Zhiti¹ thought it as the reduction of tannin was destroyed, but oxidation and polycondensation aggravated and the necrotic layer thickened when the graft union was filled up by xylem bleeding. (2) For the content of phenols was higher in walnut, phenols oxidiation was accompanyed by the protein deposition to produce insoluble polyphenols to form dark necrotic layer when grafting, which affected the grafting survival by cutting off the interchange between the scions and stocks of the graft union.

The study was carried out with three kinds of walnut varieties

I International Symposium on Walnut Production

X. Rongting, D. Pinghai

https://doi.org/10.17660/ActaHortic.1990.284.10