Anatomical observations on formation and development of adventitious root primordium in canes of Vitis sp.

Understanding the anatomical aspects of adventitious root primordium formation can provide valuable insights into the improvement of propagation techniques, rootstock selection, and overall vineyard management practices in Vitis spp. This work was carried out to investigate anatomical root primordium formation in the rooted cuttings of Cabernet Sauvignon (CS, Vitis vinifera L.) and the rootstock Kober 5BB (Vitis berlandieri x V. riparia) with their relationship to stem anatomy. One-node cuttings were grown under temperature-controlled conditions for 8 weeks. After removal of the roots and calli, the stem parts were fixed in a fixative solution. A revised method of safranin staining was applied to the 90 µm thick cross-sections made with a hand microtome. It was observed that root primordia were derived from the two different regions of the cane tissues: from the groups of cells close to the outside of the conductive tissue system and from the cell groups in the deeper site, close to the pith. Cultivars showed significant differences in terms of the regions where they had their root primordial initials. Number of potential root primordia was statistically higher in CS. Both CS and 5BB had root angles in the range of 83° to 86°. It was concluded that grapevine cuttings had only induced root primordia and the capacity to produce them was dependent on the genotype. Formation and development of root primordia and the anatomical differentiation of the cell groups were similar in Cabernet Sauvignon and 5BB.