Plastic petri dishes

To test for the presence (or not) of PY, seed imbibition of water was determined under laboratory conditions (approximately 23 ± 2°C, RH of 40–50%). Four replicates of 100 C. takesimana seeds were weighed using an electronic balance (ML204/01, Mettler Toledo, Columbus, OH, USA), and then seeds were placed on two layers. Thereafter, C. takesimana seeds from each replicate were individually placed on two layers of filter paper (Whatman No. 2, Toyo Roshi Kaisha, Ltd., Tokyo, Japan) moistened with distilled water in four 90 × 15 mm plastic Petri dishes (SPL Life Sciences Co., Ltd., Pocheon, Korea). After 3, 6, 9, 12, 24, 72 and 96 h of incubation, each replicate of seeds was weighed. Water was removed from the seed surface with paper towels, and after weighing seeds were returned to the moist filter papers. The percentage increase in mass due to absorption of water by the seeds was calculated using the following formula [16 (link)].
$$\%{\mathrm{W}}_{\mathrm{s}}=[({\mathrm{W}}_{\mathrm{i}}‐{\mathrm{W}}_{\mathrm{d}}/{\mathrm{W}}_{\mathrm{d}})]\times 100$$
where W_s indicates the increase in seed mass, W_i is the seed weight after a given imbibition interval, and W_d is the original seed weight before water absorption.

To test for the presence (or not) of PY, seed imbibition of water was determined under laboratory conditions (approximately 23 ± 2°C, RH of 40–50%). Four replicates of 100 C. takesimana seeds were weighed using an electronic balance (ML204/01, Mettler Toledo, Columbus, OH, USA), and then seeds were placed on two layers. Thereafter, C. takesimana seeds from each replicate were individually placed on two layers of filter paper (Whatman No. 2, Toyo Roshi Kaisha, Ltd., Tokyo, Japan) moistened with distilled water in four 90 × 15 mm plastic Petri dishes (SPL Life Sciences Co., Ltd., Pocheon, Korea). After 3, 6, 9, 12, 24, 72 and 96 h of incubation, each replicate of seeds was weighed. Water was removed from the seed surface with paper towels, and after weighing seeds were returned to the moist filter papers. The percentage increase in mass due to absorption of water by the seeds was calculated using the following formula [16 (link)].
$$\%{\mathrm{W}}_{\mathrm{s}}=[({\mathrm{W}}_{\mathrm{i}}‐{\mathrm{W}}_{\mathrm{d}}/{\mathrm{W}}_{\mathrm{d}})]\times 100$$
where W_s indicates the increase in seed mass, W_i is the seed weight after a given imbibition interval, and W_d is the original seed weight before water absorption.

The permeability of seeds was determined to identify their PY under laboratory conditions (approximately 23 ± 2 °C, RH of 40–50%). Nontreated (with endocarp) and ER seeds were used in the water absorption rate test. Four replicates of 25 seeds each were initially weighed using an electronic balance. Subsequently, R. scandens seeds from each replicate were individually placed on two layers of filter paper (Whatman No. 2; Toyo Roshi Kaisha, Ltd., Tokyo, Japan) moistened with distilled water in 90 mm × 15 mm plastic Petri dishes (SPL Life Sciences Co., Ltd., Pocheon, Republic of Korea). Water was removed from the seed surfaces using paper towels, and the increase in mass for water absorption was determined after 3, 6, 9, 12, 24, 48, and 72 h of incubation. The water absorption rate of seeds was calculated using the water uptake formula [17 (link)].

where W_s is the increase in seed mass, W_i is the seed weight after a given imbibition interval, and W_a is the original seed weight before water absorption.