Evaluation of different methods to overcome <i>in vitro</i> seed dormancy from yellow passion fruit

Abstract

Seeds from yellow passion fruit (Passiflora edulis Sims) present dormancy imposed by the seed-coat. The present study aimed to evaluate some methods to overcome dormancy of seeds from P. edulis grown under in vitro conditions. The experimental design was completely randomized in factorial scheme (15 scarification methods × 2 substrates: PlantMax^® and MS medium), constituting 30 treatments with 10 replicates. The following treatments were established: Control (untreated seeds); seeds soaked in water at room temperature for 12, 24 and 48 h; seeds soaked in hot water at 80°C for 1, 2.5 and 5 min; chemical scarification with sulphuric acid (98%) for 1, 5, and 10 min; immersion of the seeds in absolute ethanol for 5, 10 and 25 min; physical scarification with wood sandpaper (no. 125); and total seed coat removal with a Gavin^® mini-vise. After each treatment, the seeds were inoculated in vitro in two sterile substrates (MS medium or PlantMax^®). The results show that the best treatment to overcome dormancy of P. edulis seeds was total removal of seed coat with Garvin^® mini-vise. This treatment yielded 100% seed germination under in vitro conditions either on PlantMax^® or MS medium. Approximately 150 seeds per hour could be decoated according to the operator’s skills. However, in some cases, there was physical damage to the zygotic embryo. Seed treated with sulphuric acid for 1 min also showed promising results (average 0.107). Seeds germinated within seven days after being treated with sulphuric acid and inoculated in vitro in PlantMax^® sterile substrate. Moreover, poor germination rates were achieved when seeds were treated with sulphuric acid, followed by inoculation in vitro onto MS medium (0.0711). All seeds germinated on in vitro PlantMax^® sterile substrate and presented an epinastic phenotype, possibly due the ethylene biosynthesis in vitro.

Keywords: Passiflora, dormancy, seed germination

African Journal of Biotechnology, Vol 13(31) 3657-3665