Effects of girdling on cleft grafting of Macadamia

Abstract

     Cleft grafting is one of asexual propagation which most commonly used for macadamia. The achievement propagation of macadamia depended on various factors included scion branch, rootstock, endosperm, plant hormones and environmental factors because it is a timber tree and very difficult to cutting propagation. This study was demonstrated in three periods including May, July and November for approach grafting on macadamia. The experiments arrangement was a randomized complete block (RCBD) with four replications in four treatments as follow: (1) control (no girdling) (2) girdling at 4 week (3) girdling at 6 week and (4) girdling at 8 week, using 25 plants per replications. The experiment was conducted at Chiang Mai Royal Agricultural Research Center in Maehea and Khunwang substations during 2016-2018. At Maehea substation showed the results of cleft grafting in May that the girdling at eight weeks was the highest survival rate of scion at 76% with significantly different from the control. Besides the cleft grafting in July, the results of the girdling at eight weeks showed the highest survival rate at 85% and significantly different from the control (47%). And the cleft grafting in November, the girdling at eight weeks was the highest survival rate at 63% and significantly different from the control (40%). In a same as the previous station, the results from Khunwang substation showed the girdling at eights in May, July and November was the highest survival rate at 62, 65, and 75% respectively and significantly different from control. In summary, girdling the scion branch at eight weeks was the highest survival rate in cleft grafting. In addition, the timing of cleft grafting at Maehea substation was showed higher survival rate in July while, Khunwang substation was represented in November.