Investigate the Possibility of Early Prediction of Sweet Cherry Graft Incompatibility by in vitro Techniques

Graft compatibility is one of the most problems in fruit tree. Determination graft compatibility, it may last a long time but it was achieved in a short time by in vitro techniques. Plants increase their capacity antioxidant rapidly when stress occurs to increase resistance and tolerance to the conditions created. Since grafting in plants is also considered a form of stress, this way. It can be said that the plant's ability to disperse excess energy and neutralize free radicals is impaired, thus increasing the antioxidant capacity to increase the resistance to stress, so in incompatible grafts increases phenolic compounds and peroxidase to minimize oxidative damage compared to compatible grafts. This study Investigation the possibility of early determination of grafting (in) compatibility of sweet cherry by compare phenolic compound and peroxidase activity in vitro techniques.

Two factorial experiment was carried out on the base of completely randomized design with three replications. Treatments including the first factor, four levels of sweet cherry cultivars “Bing’’, “Takdaneh”, “Siyah Mashhad”, and “Adli” and the second factor, four levels of rootstocks Gisela-5, Gisela-6 (compatibility control), Mahaleb-168, and GF-305 (incompatibility control). Measurement of total phenolic compounds was determind according to the Folin-Ciocalteu method (Singleton et al., 1999). Antioxidant enzyme extraction was determined with the method of Mac Adam (1992) with some modifications. Analysis of variance was carried out by SAS software ver. 9.1 and mean comparison was conducted using LSD test.

The result showed that the highest and lowest percentage of grafting were “Bing” cultivar on Gisela-6 rootstock with an average of 64.21% and “Bing” cultivar on GF-305 rootstock of 1.1%. The highest number of leaves and longitudinal growth of scion was in “Bing” cultivar on Gisela-6. The highest number of roots and root lengths were in “Takdaneh” cultivar on Gisela-6 and “Bing” on Gisela-6. The highest amount of total phenol at the graft union was GF-305 and the lowest at the graft union was Gisela-5. The highest and lowest of peroxidase were at the graft union of “Bing” on-G5-305 and “Bing” and “Siyah mashhad” on Gisela. In general, the highest levels of total phenol and peroxidase at the graft union were higher on the GF-305 incompatible rootstock than Gisela-6 compatible rootstock. Therefore, our finding leads to the conclusion that phenolic compounds and peroxidase activity can be used to pre-screen for incompatible grafts. In general, the amount of total phenol in the grafts made on Gisela-6 (compatible control) and Gisela-5 rootstocks was less than GF-305 (incompatible control). GF-305 is incompatible with cherry cultivars. Phenolic compounds such as Catechins above the graft site can be used as a biochemical marker in the diagnosis of graft incompatibility (Baron et al., 2019). Peroxidase levels in incompatible grafts were higher than compatible grafts. It seems that the peroxidase enzyme can be used to predict incompatible grafts quickly. Preliminary analyzes on the role of peroxidase indicate that this enzyme is involved in the formation of cell wall constituents and in the next step reduces the flexibility of the cell wall by creating cross-linking between phenolic polymers of the cell wall (Cassab & Varner, 1987).

The highest levels of total phenol and peroxidase at the graft union were higher on the GF-305 incompatible rootstock than Gisela-6 compatible rootstock. Therefore, the finding of this study leads to the conclusion that phenolic compounds (mostly) and peroxidase activity can be used to pre-screen for incompatible grafts