Paclobutrazol as a strategy to induce reproductive precocity in sour passion fruit

Abstract The adoption of growth regulators can be an alternative method to modulate the quality of the propagation material and obtain reproductive precocity. The objective was to evaluate if a gibberellin biosynthesis inhibitor affects the morphophysiological, biochemical and anatomical parameters of sour passion fruit seedlings and if such alterations affect the reproductive period. Two trials were conducted. In trial I, 40 days after emergence, the seedlings were immersed up to the substrate level in paclobutrazol (PBZ) solutions at concentrations of: 0, 40, 80, 120 and 160 mg L-1. At 45 days after the application of PBZ - DAA, the morphophysiology, biochemistry and anatomy were evaluated. Trail II was conducted in pots, using seedlings from trail I with 45 DAA of PBZ. At 200 days after transplanting, accumulation of shoots and roots fresh and dry mass (g), flowering speed index, total number of reproductive organs and SPAD index were evaluated. In seedlings, restriction of shoot growth induced by PBZ was associated with root increment, seedling quality, photosynthetic pigments and optimization of gas exchange. A shorter period of transition from the juvenile – vegetative phase to reproductive is observed when the seedlings were submitted to PBZ concentrations.