Almond is a nutritive fruit, rich in monounsaturated fats, protein, and antioxidants. In Portugal, almonds are a traditional culture in the north and south. However, new orchards are being installed mainly in irrigated systems using commercial varieties neglecting the traditional cultivars. Micrografting, grafting in vitro conditions, involves the placement of a shoot explant into a decapitated rootstock in sterilized conditions [1]. This technique allows rapid and large-scale multiplication, and it has been used for the production of disease-free plants, rejuvenation of mature tissues, and to determine the compatibility between the scion and the rootstock. Only a few protocols have been established for commercial almond trees [2], but no studies have been described with Portuguese varieties.
The main objective of this work was to optimize new and efficient protocols of almond micrografting with traditional varieties (Rabo de Zorra, Gama Dura and Canhota), known for their high fruit quality. The effect of plant growth regulators (BAP and IBA) and activated charcoal on culture medium were evaluated during micrografting assays. In addition, rooting assays of bitter almond rootstock were also analysed. The healing percentage of micrografts observed was higher than 87%. Auxin IBA was important for root induction of rootstocks during micrografting and rootstock assays. However, the IBA dipping procedure (IBA 1 mg/L) presented higher rooting rates (60%), when compared to MS medium supplement with IBA (27%) in the same concentrations. In the future, the success of almond micrografts will be evaluated in ex-vitro conditions, namely in field tests.
Reference:
[1] Hussain, G., Wani, M.S., Mir, M.A., Rather, Z.A., Bhat, K. M., (2014). Micrografting for fruit crop improvement. African Journal of Biotechnology, 13, 2474-2483.
[2] Yildirim, H., Akdemir, H., Süzerer, V., Ozden, Y., Onay, A., (2013). In Vitro Micrografting of the almond Cultivars “Texas”, “Ferrastar” and “Nonpareil”. Biotechnology & Biotechnological Equipment, 27:1, 3493-3501.
