Daminozide modulates germination and vegetative growth of yellow passion fruit

Abstract Passiflora edulis Sims. f. flavicarpa Deg. (yellow passion fruit) is a tropical species of high economic importance for which seeds constitute an important source of propagules and genetic variability. Controlling vegetative growth can facilitate seedling management and reduce excessive internode elongation, resulting in more compact plants. Daminozide is a growth retardant used in ornamental plants whose physiological effects on passion fruit seeds and seedlings are still poorly understood. In this study, we analyzed the effects of daminozide exposure during seed imbibition and germination on the physiological quality and initial growth of P. edulis f. flavicarpa seedlings. Seeds were soaked for 12 h in solutions containing 0.0, 0.2, 0.5, 1.0, or 2.0 g L − 1 of daminozide, and then were germinated in paper rolls in a BOD incubator at alternating temperatures of 20/30°C. Germination percentage, germination speed index, mean germination time, and hypocotyl length, root length, epicotyl length, aerial part length, and total plant length were evaluated. Seedlings were grown for 120 days for aerial part and total plant length measurements and qualitative stem anatomical analysis. The highest concentrations of daminozide (1.0 and 2.0 g L − 1 ) increased germination percentage and speed, but progressively reduced hypocotyl length, epicotyl length, root length, aerial part length, and total plant length. Qualitative histological observations suggested differences in the apparent organization and dimensions of stem tissues among treatments. Exposure to daminozide during seed imbibition and germination increased germination percentage and reduced vegetative growth of P. edulis f. flavicarpa .