Abstract
Satureja rechingeri Jamzad, which belongs to the Lamiaceae family, is a rich source of essential oil particularly carvacrol, and rosmarinic acid. Salinity stress significantly impacts plant growth and biochemical traits. The present study aimed to examine the impact of exogenously applied putrescine (PUT) polyamine (0, 1, 2, 3, and 4 mM) on the agro-morphological, physio-biochemical, and phytochemical traits of S. rechingeri plants cultivated under different levels of salt stress (0, 50, and 100 mM NaCl). Conducted as a factorial experiment with a completely randomized design. Results showed that PUT application ameliorated the negative effects of salt stress on agro-morphological traits, including plant height, leaf dimensions, biomass, and essential oil yield, alongside increased cell membrane integrity and leaf chlorophyll. Under severe salinity, biomass reduction by 55-60% was improved by up to 80% with 4 mM PUT. PUT also increased cell membrane integrity and chlorophyll content, with the highest chlorophyll enhancement observed at 4 mM PUT. In addition, higher PUT concentrations under salinity stress significantly promoted phytochemical traits. TPC and TFC increased by up to 34% and 51%, respectively, while rosmarinic acid rose by about 19% compared with untreated stressed plants. Essential oil content increased under salinity by 20-44%, and PUT application further elevated essential oil yield by more than 60%. Also, observed reducing in cell membrane damage, osmolytes like proline, antioxidant enzymes activity including superoxide dismutase (SOD), peroxidase, and catalase (CAT), with application of PUT under salinity stress that highlighting PUT potential in increasing in antioxidant activity in order to decreasing ROS and reprograming osmolytes like proline, and antioxidant enzymes activities in order to enhancing plants resilience to salinity stress. Overall, putrescine application can be considered an effective approach to enhance the salinity tolerance of S. rechingeri, while improving agro-morphological parameters, secondary metabolite production, and supporting agricultural sustainability and essential oil production.