Mini-grafting of adult Passiflora edulis Sims f. flavicarpa Deg. scions onto vegetatively propagated adult rootstocks of P. mucronata Lam

Abstract

The mini-grafting is a nondestructive vegetative propagation method based on grafting apical segments onto adult donor plants-derived rootstocks. Here, we aimed at evaluating the mini-grafting of shoot tips derived from adult Passiflora edulis f. flavicarpa plants (yellow passion fruit) onto vegetatively propagated rootstocks of P. mucronata (sandbank passion fruit). Different shoot tip lengths and the fastening material were assayed. A randomized block experimental design was set up following a 2 × 3 factorial scheme [shoots: 8-12 and 3-7 cm × fastening materials (circular clip, "V" shaped clip, and Parafilm®)] totaling six treatments with four repetitions of eight plants each. The following characteristics were evaluated: graft setting (%); graft and rootstock diameters (mm); graft diameter/rootstock diameter ratio; cellular division in the graft region and starch presence in the graft and rootstock. Parafilm® provided better adhesion (89.57%) compared to circular (76.03%) and "V" shaped clips (68.74%). The attachment was favored by rootstocks with 8-12 cm shoots (90.27%), compared with those of the 3-7 cm (65.96%). The presence of starch grains in the parenchymatic cells of the graft suggests the translocation of photo-assimilates from physiologically active mature leaves of P. edulis f. flavicarpa to the stem apex. Additionally, the hydrolysis and mobilization of the starch associated and the endogenous auxin levels in this meristematic region may have been responsible for improving the success of the mini-grafting.