Pre-Germination Treatments, Temperature, and Light Conditions Improved Seed Germination of Passiflora incarnata L.

Perennial medicinal and aromatic plants (MAPs) may represent interesting, environmentally friendly crops for the Mediterranean environments. Among MAPs, Passiflora incarnata L. (maypop) represents a very promising crop for its wide adaptability to diverse climatic conditions, low input requirements, and high added-value due to its unique medicinal properties. The main problem in P. incarnata large-scale cultivation is the poor seed quality with erratic and low seed germination, due to its apparent pronounced seed dormancy. Therefore, the aim of this work was to investigate different chemical and physical treatments for overpassing seed dormancy and enhancing seed germination rates of P. incarnata. The effects of (i) different pre-germination treatments (pre-chilling, gibberellic acid—GA3, leaching, scarification, non-treated control), (ii) light or darkness exposure, and (iii) temperature conditions (25, 30, and 35 °C constant and 20–30 °C alternating temperatures) have been examined in seed germination percentage and mean germination time of three P. incarnata accessions (F2016, FF2016, and A2016) grown in field conditions in Central Italy. Data showed that the pre-germination treatments generally stimulated faster germination compared to the control, with the best results obtained in the dark and with high temperatures. These findings are useful for the choice of the most suitable seed pre-germination treatment that can facilitate stable, high and agronomically acceptable germination rates in P. incarnata.