Usability of blackthorn (Prunus spinosa) and some almond (Prunus amygdalus) rootstocks as rootstock for late flowering almond cultivars

In this study, it was aimed to determine the graft compatibility status of Ferrduel, Ferragnes, Makako, Tarraco, and Vairo almond cultivars with GF-677 rootstock and Prunus spinosa inter-stock at early stage. P. spinosa used as inter-stock was grafted onto GF-677 rootstock using tongue cleft grafting method, while almond cultivars were grafted onto P. spinosa using chip budding grafting method. Sections of graft samples were taken 15, 30, 45, 60, 90, and 120 days after grafting in budding grafts and 150 days after grafting in cleft graft. The taken sections were anatomically and histologically examined. In budding grafts, the highest graft success was found in P. spinosa/Makako combination with 96.66%, while the lowest graft success was found in P. spinosa/Ferraduel combination with 83.33%. In cleft graft, graft success in GF-677/P. spinosa was determined as 96.50%. When examined the taken graft sections, it was observed that callus formation started on the 15th day after grafting. It was determined that the previously formed callus developed further and cambial differentiation started on the 30th day. It was detected that the cambium connection was established between the graft elements and a distinct callus bridge was formed on the 45th day. It was observed that union between rootstock and scions was completed, callus tissue filled the space between rootstock and scions more than the previous period, and most of the callus tissue was differentiated to xylem cells on 60th day. It was determined that the newly differentiated cambium tissue produced new vascular tissues by maintaining its continuity along the entire graft surface, parenchymatic cells with a regular structure were formed between these tissues, and the newly formed vascular elements fulfilled their functions among the graft elements on the 90th day. It was detected that the graft union continued in majority of the combinations (60%), while all stages of the graft union occurred in some combinations (40%) on the 120th day. In conclusion, no indication of the graft incompatibility was encountered in the combinations.