Abstract

The purpose of this study is to develop an appropriate protocol aiming to improve the rooting capacity of carob (Ceratonia siliqua L.) explants grown in vitro. Rooting is known to be difficult for this species, which therefore hinder the propagation of productive genotypes. Explants prepared from germinated seeds of C. siliqua L. were exposed to two sonication durations 15 and 30min at a frequency of 42 KHz. A combination of optimal sonication (15min) with hormonal (IBA) treatment was applied by immersing the basal part of the explants in three different concentrations (0.5, 1, and 2 mg/l). The results of sonication were significant on the parameters of aerial and root growth. The exposure time of 15 min is the best compared to the 30 min. Hormonal treatment (alone or in combination with sonication) has a positive effect on the length of the plant, and the number and length of the roots. The results show significant differences with control at 2 mg/l IBA treatment combined with 15min sonication, or 15min sonication followed by 2 mg/l IBA treatment (dark, 12 h, and 5°C). The results of these experiments show that sound wave stimulation can certainly promote plant growth. Furthermore, this protocol offers a new root induction pathway for cultivars characterized by low rooting capacity in nature.