Study of The Compatibility by Field Grafting and Micrografting Between Some Almond Cultivars and its Wild Species

The research was carried out at the Abo-Jarash farm in Agriculture Faculty of Damascus university and the Laboratory of Biotechnology for Medicinal Plants of the National Commission for Biotechnology/ Damascus, during the period between 2018–2021, on four almond cultivars (Prunus dulcis cvs. Shami Furk, Dafadii, Ferragnes , Fournat) and four wild almond species (P. communis, P. orientalis, P. korschinskii , and P. arabica) to investigate the grafting and micrografting compatibility between these cultivars and wild Species.The results indicated that the P. communis exceeded significantly in the seed germination percentage, also, P. korschinskii exceeded in the highest persent of grafted- seedling (66%) at two years aged, compared to the rest of the tested species, Meanwhile, P. arabica seedling didn’t reach to the suitable grafting thickness.The result of field grafting clarified that a superiority of all the cultivars grafted onto P. korschinskii and P. communis rootstocks in the grafting success rates (78.05%, 75.94%), length of scions (33.30 cm, 27.72 cm) and its diameter (2.32 mm, 2.31 mm), respectively, compared to the grafting on P. orientalis. As for the anatomical study of union zone of grafting between scion/ rootstock combinations, cross sections taken after four week from grafting showed division of new formed cambium and few tissues of xylem were differentiated in all cultivars grafted on P. korschinskii and P. communis while it was observed semi compatible between Dafadii cultivar and P. orientalis rootstock0The results of micropropagation of tested cultivars indicated that the best results of surface disinfection were obtained when treatment with sodium hypochlorite at a concentration of 0.5% for 10 minutes then mercury chloride 0.1% for 30 seconds. Murashige and Skoog (MS) medium, supplemented with 1 mg.l-1 benzyl adenine (BA), 0.1 mg.l-1 indole-3-butyric acid (IBA) and 0.2 mg.l-1 gibberellic acid (GA3), achieved the highest shoot multiplication rate for Shami Furk and Dafadii cultivars, as for Ferragnes cultivar, the highest shoot multiplication rate achieved when 1 mg.l-1 BA + 0.2 mg.l-1 GA3 were added to MS media. The highest rooting rates with the largest average number of roots for studied cultivars (Shami Furk, Dafadii, Ferragnes) were obtained when using IBA auxin at a concentration of 1 mg.l-1, and the acclimatization percentages ranged between 50% for Ferragnes and 85% for Shami Furk.The result of micropropagation of tested species showed that the highest significant average number of shoots/explant and the longest shoot for both P. arabica and P. korschinskii were obtained in a medium supplemented with 1 mg.l-1 BA+ 0.1 mg.l-1 IBA+ 0.2 mg.l-1 GA3, whereas, P. orientalis and P. communis achieved the highest significant average number of shoots/explant and the longest shoot by using hormonal combination 1 mg.l-1 BA + 0.2 mg.l-1 GA3.The results showed the rooting improved when microshoots incubation immediately after planting on the rooting media for 7 days in the dark. It was also found that reducing macro elements concentration raised the rooting percentage of all tested species (P. arabica, P. korschinskii, P. communis, P.orientalis), and acclimatization percentages ranged between 60%-94%, P. orientalis was the best (94%).The result of micrografting, the highest grafting success rates obtained from Shami Furk/P. Arabica, Ferragnes/ P. Arabica and Dafadii/P. arabica combinations, while the lowest success rate was 50.63% with the Dafadii/P. orientalis combination. The liquid MS medium supplemented with 0.5 mg.l-1 BA + 0.1 mg.l-1 IBA achieved the highest micrografting success and scion shoot length.In conclusion, the results and observations in this research demonstrate the importance of using the P. korschinskii, P. arabica and P.communis as rootstocks for the tested almond cultivars, consequently, this research can be used to improve almond cultivation