A protocol for in vitro multiplication of caper (Capparis spinosa L. subsp. rupestris) from nodal segments collected from mature plants was developed. For shoot multiplication, one auxin (indol-3-butyric acid, IBA) and cytokinins of two different classes were used: the N6-substituted adenine derivatives 6-benzylamino purine (BAP), and the two synthetic phenylurea derivatives N-phenyl-N′-benzothiazol-6-ylurea (PBU) and N-phenyl-N′-(1.2,3-thidiazol-5-yl) urea (thidiazuron, TDZ). Maximum shoot production was achieved from explants cultured with the adeninic cytokinin BAP (4 μM) and the auxin IBA (0.5 μM). New shoots longer than 1 cm were used for rooting. To induce root formation, three auxins [indole-3-butyric acid (IBA), 1-naphthaleneacetic acid (NAA) and 3-Indoleacetic acid (IAA)] and two synthetic phenylurea derivatives [N,N-bis-(2.3-methylenedioxyphenyl)urea (2.3-MDPU) and N,N-bis-(3.4-methylenedioxyphenyl)urea (3.4-MDPU)] were used. All rooting compounds tested stimulated the formation of roots. However, the best result in terms of a high percentage of rooted shoots having a well-developed root system with many lateral roots was achieved with the synthetic phenylurea 2.3-MDPU (1 μM) with 93.7% of well rooted plantlets. About 80% of rooted plantlets were successfully acclimatized and transferred to the greenhouse.
