Mitigation of salt-stress effects by moringa leaf extract or salicylic acid through motivating antioxidant machinery in damask rose

Despite the fact that damask rose (Rosa damascena Mill. var. trigintipetala Dieck) is an economically important aromatic plant, its growth and development has been severely suppressed by salt stress. Reports show that moringa leaf extract (MLE) or salicylic acid (SA) are involved in salt-stress tolerance. Nevertheless, scarce information is available about MLE or SA impacts on aromatic plants, especially damask rose under salinity. This investigation was, therefore, conducted to investigate the effects of MLE and (or) SA on salt-stress mitigation in damask rose. Rose plants were treated with 200 mmol·L−1 sodium chloride, and foliar applied with MLE at 1:30 (v:v) and (or) 0.2 mmol·L−1 SA. Foliar spraying with MLE and (or) SA enhanced the growth attributes, chlorophyll content, relative water content, proline content, and membrane stability index under salinity. Less accumulation of malondialdehyde and H2O2 was also observed when MLE and (or) SA were applied. Furthermore, MLE and (or) SA applications considerably increased the radical scavenging activity, total phenols, and antioxidant enzyme activity (catalase and superoxide dismutase) under stress. The mitigative effect of MLE or SA was more pronounced when they were applied in combination. Collectively, MLE and (or) SA had efficient antioxidant defense system that scavenged reactive oxygen species, and thus afforded considerable protection against salt-induced oxidative damage.