The cell regeneration and conection on grafting between pear and quince trees is defined by cortex and phloem

Abstract

Pear cultivation in the tropics currently requires the complex use of Pyrus calleryana or Chaenomeles sinensis rootstocks with Cydonia oblonga interstocks. However, there is a disagreement in the literature regarding the tissues that are responsible for regeneration during grafting, especially during intergeneric grafting. The objective of the present study is to quantify the different proportions of tissues in rootstock-interstock combinations established to obtain saplings. Packham's Triumph pear (crown) was double grafted by cleft grafting onto interstocks of C. oblonga (Adams, BA-29, EMA, EMC and Sydo cultivars), and these combinations were subsequently grafted onto C. sinensis or P. calleryana rootstocks. The sprouting percentage was evaluated 150 days after sprouting. Subsequently, the anatomy of the connections between the crown and interstock and the interstock and rootstock was examined. The following characteristics were evaluated: xylem parenchyma ray area of each grafting component (scion, interstock and rootstock); total connection area; connection areas between xylem-xylem, phloem-phloem, phloem-cortex, and cortex-cortex; percentage of xylem, phloem, and cortex for all materials; rootstock area; interstock area; scion area; rootstock/interstock connection area; interstock/scion connection area; and areas with no connection or with necrosis. The data were subjected to analysis of variance and the ScottKnott test (P ≤ 0.05), and correlations between tissue percentages and connection areas were calculated and considered significant when R 2 ≥ 0.6. Only the tissues composing the cortex and phloem were positively correlated with the connection area. The P. calleryana rootstock has greater compatibility with the interstock due to its greater proportion of cortex. The xylem parenchyma rays do not significantly influence cell regeneration or connection. Therefore, woody species that contain more cortex and phloem in the rootstock and/or scion will have greater potential for grafting success.