Evaluation of cuttings ability of eighteen pomegranate cultivars from an ex-situ collection under influence of stem age and IBA treatment

The present experiment was conducted to assess the ability of the cutting of 18 pomegranate cultivars, 10 of which are local types and the other 8 are exotic varieties. The experiment was carried out in the controlled greenhouse, using two types of cuttings, semi-hardwood and hardwood and 4 IBA treatments (0, 1000, 2000 and 3000 mg L⁻¹). The measurements concerned biometric parameters of the roots (rooting rate, number of roots produced per cutting, root length, root weight) and vegetative growth of the aerial part (apical shoot growth, total shoot length, number of primary and secondary shoots). The rooting rate was influenced by the cuttings type, IBA concentration, and genotype. The hardwood cuttings had a higher rooting percentage and shoots growth than semi-hardwood cuttings in most cultivars. The effects of IBA treatments on rooting and vegetative growth of the cuttings significantly differed according to the genotype. Maximum rooting, root number, and root length were observed by using an IBA concentration of 3000 mg L⁻¹. The highest rooting rates were observed in ‘Zheri Precoce’ (90%), ‘Wonderful’ (90%) and ‘Chioukhi’ (80%), while the lowest rates were found in ‘Bzou’ (30%) and ‘Grenade Rouge’ (40%). Furthermore, there were large differences between cultivars in terms of vegetative traits. Among the studied cultivars, ‘Zheri Precoce’ and ‘Chioukhi’ showed the highest number of shoots and shoot length. It was concluded that the hardwood cuttings are more suitable for pomegranate propagation by cutting, with the use of high IBA concentrations. The pretreatment of cuttings by 3000 mg L⁻¹ is sufficient for most cultivars, while higher concentrations seem necessary to increase the rooting rate of certain cultivars.