Abstract

We investigated the in vitro effect of the use of Ulva rigida extract as a plant stimulant on carob root induction. Treatments at different concentrations of U. rigida extract were tested, as well as treatment by immersion of the basal portion of the hypocotylar sections in a solution of indole-3-butyric acid (IBA) before their cultivation in agar medium contains seaweed extract have been tested. The results showed that the application of U. rigida significantly increased the growth and rooting of carob cuttings. Plants treated with U. rigida extract outperformed the untreated plants in terms of plant height, number of internodes, number of leaves, number of roots, and root length with a high percentage of rooting of 83%. The higher response in the adventitious roots of carob hypocotyl cuttings was recorded with a treatment combination with IBA at a concentration of 2 mgL-1 and culturing in a medium containing 4% U. rigida extract. The results demonstrate a significant effect of U. rigida extracts on the root development of Ceratonia siliqua. This study highlights the possibility of developing procedures to improve the rooting capacity of recalcitrant plants while improving their growing environment.

Key words: Ulva rigida, Ceratonia siliqua, roots, in vitro growth, seaweed extract