Studies on Some Scion-rootstock Physiological Indexes Related to Micrografting Survival of Walnut

Walnut microshoot grafting is a new technique using juvenile seedlings as rootstocks and shoots in vitro as scions to propagate walnut cultivars.Some tests were carried out to focus on the relation between scion-rootstock physiological states and grafting survival.Results were that during the first main leaf expanding,there was a significant change of the physiological metabolism in rootstock seedings,which was closely related to the grafting survival.Before the leaf was fully expanded,the level of cytokinin,auxin,water content,glucose and levulose in rootstock was higher,the grafting uniting can easily be achieved and the survival rate was more than 80.8%.After the leaf expansion,the physiological indexes went down and the grafting uniting became more and more difficult.The physiological state on shoots in vitro and their grafting also demonstrated that the tender,fast growing and strong shoots showed higher levels of the physiological indexes,and their grafting survival rate was higher,whereas the old,thin and longer shoots with twisted leaves showed lower levels of the indexes,and their grafting was difficult.