Propagação, desempenho e sobrevivência a estresses bióticos de maracujazeiro amarelo enxertado em espécies de passiflora

Abstract

Yellow passion fruit cultivation has a major socioeconomic importance in Brazil, especially in the Northeast region, even though the increasing incidence of several diseases in the last years has been affecting its cultivation. Researchers have been studying this crop management that associated with breeding and alternative grafting of susceptible varieties onto resistant rootstocks may be promising. This work evaluated the propagation and the performance of Passiflora spp. in three trials with the following objectives, in this order: 1) evaluate plant emergence and initial growth of wild species with potential use as rootstocks after immersion of stored and fresh seeds in four gibberellic acid (GA3) concentrations and obtained from fruits on different maturation stages; 2) determinate the tying material that leads to the highest hipocotyledonar budtake of yellow passion fruit grafted onto wild species; and 3) evaluate growth, fruit set and survival of these graft combinations in an area with high incidence of virosis, antracnosis and fusariosis. Species evaluated were Passiflora alata, P. cincinnata, P. setacea, P. gibertii and P. edulis, cultivated as seedlings or grafted with yellow passion fruit. The immersion of seeds stored for 11 months in cold chamber in GA3 solution at 1000 mg L-1 did not increase emergence and initial growth of Passiflora spp. rootstocks, with P. alata and P. cincinnata lacking emergence under these conditions. On the other hand, seeds that were extracted from just-harvested ripe fruits presented higher and faster emergence and plant growth after the immersion in GA3 solutions from 500 to 1000 mg L-1, regardless of the passion fruit species. Fruits in the maturation stages of pre-ripeness, ripeness and senescence led to similar seed emergence. The use of masking tape, metallic hair clip and spring plastic graf clip as tying materials resulted in high budtake without differences among the treatments. Therefore, their use can be recommended for yellow passion fruit grafting. Plant growth was higher for grafts onto P. edulis and P. gibertii in relation to P. alata, 90 days after hipocotyledonar grafting. Seedlings of P. edulis, P. gibertii, P. cincinnata and P. alata had higher plant growth and similar flowering and fruit set in comparison with P. edulis grafted on the same species, 13 months after field transplantation, with the exception of reduced flowering and fruit set in the combination P. edulis / P. gibertii. The grafting of P. edulis onto P. gibertii, P. cincinnata and P. alata led to lower survival to fusariosis and similar response to antracnosis and virosis in relation to plants grafted onto P. edulis and to the respective seedlings, in the same period of evaluation.