Ex vitro interspecific micrografting in passionflower

Abstract

This study aimed at evaluating the effect of Passiflora species used as rootstocks on the success and development of ex vitro interspecific micrografting, and at anatomically characterizing the region where it is done. Stem apices of Passiflora edulis f. flavicarpa were grafted onto the hypocotyl of P. alata, P. cincinnata, P. edulis, and P. setacea seedlings. The micrografting development, the occurrence of adventitious shoots in rootstocks and the percentage of micrografts with expanded leaves were evaluated. The rootstocks were subjected to anatomical and histochemical evaluation. Micrograft development and adventitious shoot number were higher when P. edulis rootstocks were used, and lower for rootstocks of P. setacea and P. alata. P. edulis, P. cincinnata, P. alata, and P. setacea rootstocks developed 30.3, 10, 1.6, and 0% of micrografts with expanded leaves, respectively. The histological evaluation revealed increased thickness of the cortical region in rootstocks of P. edulis, while in P. setacea a lower number of cortical layers, increased phloem fibers, and increased alkaloids were observed, characteristics that negatively influenced the micrografting outcome.