Study on Parameters of Rootstock and Scion About Grafting of Pitaya

Objective This study was made to perfect grafting technique and parameters of rootstock and scion of pitaya so as to improve grafting survival rate and ensure bud sprouting in time.

Method 'Hongshuijing No.6' pitaya was selected as test material. Rootstocks were cut from ripe or green ripe vine-type shoots with different lengths. Mixed orthogonal array design (OAD) and OAD were used to observe the effect of rootstock position in vine, grafting method, number of buds per scion and scion maturity on grafting survival. Multivariate analyses on parameters of rootstock length, mass, ratio of mass to length, rootstock circumference and scion length were conducted with whether scion sprouted or not and scion sprouted time as the dependent variable respectively.

Result The grafting survival rates of short ripe and green ripe vines, cut into 2 sections averagely for rootstocks, were 75.0% and 87.5%, respectively. Long ripe vine, cut into 3 sections averagely for rootstocks, was unfit to be grafted with one bud scion. The middle section from long green ripe vine was unfit for rootstock. It was estimated that longer rootstock, rootstock with lower ratio of mass to length and slight maturity, and longer scion might be suitable for grafting. Scions grafted on shorter, thicker and heavier rootstocks with higher ratio of mass to length and maturity were prone to germinate later or even unable to germinate.

Conclusion The basic principle of the grafting of 'Hongshuijing No. 6' rootstocks was preliminarily determined. 1-2 years old vines, preferably green ripe vines, may be used for rootstocks. However, the middle section of long green ripe vine was unfit for rootstock. Rootstock length was not less than 40 cm. Scions were selected from solid stems near growing point and cut from up to down for grafting. Scion length was not less than 3 cm with 2 buds at least. Flat grafting was preferred. The grafting technique proved to be effective and practical after mass grafting was carried out with high survival rate of 81.2%. Therefore, it was advocated to be used for breeding and production of pitaya seedlings.