Drill grafting application in pistachio (Pistacia vera L.)

Our study was conducted in the Gökçebağ town of the Central district of Siirt province, in an orchard with pistachio trees between the ages of 40-45, established by grafting the Siirt variety onto the Menengiç rootstock. In order to rejuvenate the pistachio trees in the orchard, drill grafting method was applied to the trees. Grafting was carried out twice, in early spring term and during flowering term. In both periods, Siirt variety was grafted onto three different pistachio trees using a drill with a tip diameter of 1-1,2 cm and scions with two shoot buds on top. In the controls carried out on 01.05.2022, it was observed that the shoot buds of the graftings made at both different times were awakened. In the grafting performed in early spring, 5 of 9 scions (55,5%) and 9 of 18 shoot buds (50%) awoke; In the grafting performed during the flowering period, it was determined that 3 of 9 scions grafted (33,3%) and 3 of 18 shoot buds (16,6%) were awakened. In the second controls made on 06.06.2022, it was determined that in the 1st and 2nd graft applications, all of the shoot buds were completely dried and there was intense gumming formation and secretion in the wound tissues opened during the grafting in the plant. The fact that the tree stems consist mainly of fungous tissues, the drill bit is thick, the graft hole and the scion diameter have a large surface area, further increased the formation of gum and significantly negatively affected the possibility of the scions grafted to fuse with the cambium tissue in the tree stem. For this reason, on 06.03.2024, the grafting process was repeated on the young branches of the trees in the same orchard, using 0,6-0,8 cm diameter drill bits instead of 1-1,2 cm diameter drill bits, only in the early spring period. The grafts were checked on 17.04.2024 and it was observed that 4 of 9 scions grafted (44,4%) and 8 of 18 shoot buds (44,4%) were awakened. In the last checks carried out on 17.05.2024, it was observed that some of the awakened shoot buds were dried, while the remaining ones showed signs of drying. As a result of our study, contact between the cambium tissues was prevented due to the gum secretion that fills the gap between the rootstock and the scion in the woody tissue of pistachio trees and grafting applications with a drill were not successful.