Tolerance mechanisms and adaptive strategies of Moringa oleifera (L) during growth and vegetative development under water stress in hydroponics

In order to highlight the potential tolerance and/or resistance of Moringa oleifera (L), to drought during two weeks of germination in vitro. Osmotic water stress was induced under semi-controlled conditions. The water potential of the culture medium was lowered by the addition of polyethylene glycol (PEG-6000). As a result, four water potentials (ѰH) were tested: 0 (control), -2; -4 and -6 MPa. Our results showed that the variations at physiological level were materialized by: A slight decrease in the germination speed, accompanied by an increase in the latency time, as the ѰH decreases. However, our results showed that the growth of radicles and epicotyls of young seedlings of M. oleifera, two weeks old, significant reductions (p<0.05) of 27.8% and 77.5%, respectively, compared to controls. Our results also showed, a high accumulation of compatible solutes, in this case proline and proteins. With respective increases, estimated at 55%, and over 100% compared to controls. In addition, the comparison of the profiles of the cationic ions, of the control seeds compared to the treated ones, shows that the latter have the possibility of accumulating more ionic cations such as K+, Ca2+ and Mg2+ which would have roles of osmoregulation. Moreover, our results plead in favor of the capacity of our species to maintain or even improve its oxidative status, materialized by the increase of the activities of total polyphenols, total antioxidant capacity, catalase and ascorbate peroxidase.