Improvement of caper (Capparis spinosa L.) propagation using in vitro culture and gamma irradiation

Some of the factors influencing the propagation of caper (Capparis spinosa L.) plants in vitro and germination of the seed were studied. The number of adventitious shoots emerging from caper stems cultured in vitro increased from 2.2 shoots per explant when the growth medium contained 2 mg/L of gibberellic acid (GA3) to 5.5 when the growth medium contained 2 mg/L zeatin riboside (ZR) and 1 mg/L naphthalene acetic acid (NAA). The best medium for callus formation from leaf and stem parts contained the growth regulators 1 mg/L 6-benzylaminopurine (BAP) and 0.1 mg/L NAA and the best medium for plant regeneration contained 1 mg/L kinetin and 0.1 mg/L indole-3-acetic acid (IAA). The effect of gamma irradiation on the growth of caper shoots in vitro was also studied. A 10 Gy dose of gamma irradiation stimulated growth of shoots up to 200% and increased shoot rooting percentage from 75 to 100%.Methods of scratching the seed coat with iron particles and treating the whole seeds with concentrated H2SO4, ultrasonic waves and gamma rays were employed for breaking the seed dormancy. Treating the seed with H2SO4 for 20 min along with scratching was very effective in stimulating germination (46% as compared with 0% for the control). Irradiating caper seeds with 100 Gray (Gy) dose of gamma rays led to 50% seed germination in vitro and 70% on peatmoss one month after culturing.

Research highlights▶ Gibberellic acid (2 mg/L) stimulates formation of adventitious shoots in vitro. ▶ A 10 Gy dose of gamma rays increases growth of shoots up to 200% in vitro. ▶ A 100 Gray (Gy) dose of gamma rays stimulates seed germination up to 70%. ▶ Treating scratched seed with H2SO4 stimulates seed germination up to 46%.