Effect of time of grafting on walnut graft success under different altitudes.

摘要

Walnut grafting failure has caused the Ministry of Agriculture in Bhutan to elude walnut industry development. This led to an experiment to investigate the effects of time of grafting under ambient conditions of four different altitude ranges on walnut graft survival. Grafting was performed in mid-December 2001, January, February, March, April and May 2002. In total, 360 grafts were made with 15 grafts for each treatment combination, comprising three replications of 5 grafts. Modified whip grafting was used for all the treatments. The scion portion of grafts were waxed and grown under ambient conditions of different altitude ranges and arranged in a randomized block design. The success of the grafts in all experiments were assessed three months after grafting, by then, the failed grafts had shrivelled and scions desiccated, and had become necrotic. The successful grafts showed considerable shoot growth. Two-analysis of variance (after angular transformation of data) for graft survival percentage showed highly significant (P&0.001) difference among the different time of grafting under different altitude ranges. March grafting resulted significantly higher graft success over the other times of grafting across the altitude ranges. There were no significant differences (P=0.05) between different altitude ranges on overall graft success (inclusive of six times of grafting)..