Germination and <i>in vitro</i> multiplication of <i>Helianthemum kahiricum</i>, a threatened plant in Tunisia arid areas

Abstract

Seeds of Helianthemum kahiricum have an excellent germination rate extending to about 90% within short time not more than four days after scarification (mechanical treatment) and a good protocol of disinfection. A high frequency of sprouting and shoot differentiation was observed in the primary cultures of nodal explants of H. kahiricum on Murashige and Skoog medium (MS) free growth regulators or with less concentration of kinetin (0.5 mg L^-1 or 1.0 mg L^-1 kin). In vitro proliferated shoot were multiplied rapidly by culture of shoot tips on MS with kinetin (0.5 mg L^-1) which produced the greatest multiple shoot formation. The kinetin had a positive effect on the multiplication and growth, but a concentration that exceeded 2.0 mg.L^-1 decreased the growth. A high frequency of rooting with development of healthy roots was observed from shoots cultured on MS/8 medium hormone-free.

 Key words: Helianthemum kahiricum, in vitro germination, multiplication, axillary buds.

 Abbreviation: Zea, Zeatin (cytokinine); IAA, indole-3-acetic acid (auxin); IBA, indole-3-butyric acid (auxin); Kin, kinetin (cytokinine); MS, Murashige and Skoog medium; NAA, 2-naphthalene acetic acid (auxin); 2iP, 2 isopentenyladenine (cytokinine).