Anatomy of Rootstocks and Scions in Four Pine Species

When performing grafts, it is thought that by using plants of the same species the engraftment rate will be high; when the above is not fulfilled, the grafter, type of graft or the origin of the scions is blamed, but the anatomy of the parts forming the graft is not considered. The aim of this study was to evaluate the anatomy of four pine species used as rootstock and scion to define which species to use as rootstock based on cambium shape and bark thickness. Before grafting, 2-cm stem fractions were cut from plants that were used as rootstocks and scions. The evaluated species were Pinus patula, P. greggii, P. leiophylla and P. teocote. Cuts of 10 μm in thickness were made to determine bark and xylem thickness. Photographs were also taken with a photomicroscope to observe the "shape" of the vascular cambium. The experimental design was completely randomized with a 4x2 factorial arrangement, using 12 measurements as the sample size with four replicates. P. patula had greater bark thickness, while P. leiophylla obtained the greatest xylem thickness. In the images of the anatomical cuts, it was determined that the vascular cambium is continuous for all the species both in rootstock and in scions, but it is only circular in the P. teocote and P. leiophylla rootstocks, and the P. leiophylla scions did not present this feature. Based on the anatomy of the cambium, P. greggii, P. patula and P. teocote scions have greater possibilities of engraftment if they are grafted onto P. teocote andP. leiophylla because the cambium is circular. Tissue anatomy is one of the areas that must be known before making grafts in order to make appropriate decisions regarding the materials to be used.