In vitro micrografting success and histological union characterization of Argania spinosa (L.) skeels scion lines grafted onto rootstock G54.

The argan tree (Argania spinosa L.) is ecologically and economically important but its propagation is difficult on a large scale due to difficulty in rooting and grafting. This study provides a preliminary protocol for rootstock preparation and micrografting, and evaluated the compatibility of three scion genotypes (G41, G27, G27/41) grafted onto the rootstock G54. In vitro seed germination on basal MS medium without plant growth regulators resulted in an 82% germination rate, resulting in a sufficient quantity of healthy rootstocks suitable for micrografting. Shoot regeneration trials identified substantial genotypic differences; G41 had the highest level of shoot regeneration (100%), at 0.1mg L⁻¹ GA3, and had the highest levels of vegetative vigor and branching potential, as confirmed by principal component analysis (PCA), whereas G27 displayed more limited morphogenetic performance. Micrografting compatibility differed significantly among the graft combinations. The G41/G54 combination achieved the highest graft success rate (80%) and the lowest necrosis rate (20%) (p < 0.001). Histological examination of G41/G54 at two months after grafting revealed callus continuity, cambial organization and lignified vascular elements spanning the graft interface, features consistent with anatomical graft-union formation. Under the tested conditions, grafting performance differed among the three scion lines grafted onto G54. Because only one rootstock genotype and one histologically examined graft combination were evaluated, these findings require validation through additional and reciprocal graft combinations, comparative histology, acclimatization and long-term survival assessment. The findings provide a preliminary basis for further development of argan micrografting protocols.