How the application of amino acids biostimulants in powder affects growth, yield, and phytochemical compositions of Ziziphora clinopodioides under salinity stress

Salinity is widely considered a critical environmental stress that poses significant challenges to crop growth and development. This study investigated the ameliorative effects of Pluramin (an amino acid-based biostimulant) on Ziziphora clinopodioides grown under saline conditions. The plants were irrigated with nutrient solutions at electrical conductivities of 0 (control), 3, 6, and 9 dS m −1 , combined with Pluramin at concentrations of 0, 1, and 2 g L −1 . As the salinity concentration increased from 0 to 9 dS m⁻¹ biometric parameters such as plant height, fresh weight, and dry weight decreased by 32.19%, 47.87%, and 24.13%, respectively. Salinity also reduced the content of essential oil (EO) however, foliar application of 2 g L −1 of Pluramin significantly improved by 53.73%, 25.00%, and 31.37% for the three levels of salinity, respectively. Furthermore, Pluramin increased the concentration of the key EO compounds menthone ( iso ), piperitone, and pulegone under both control and saline conditions. In conclusion, although salinity affected the quantitative and qualitative parameters of Z. clinopodioides , the foliar application of Pluramin could mitigate the negative effects of salinity stress. These findings suggest that Pluramin is a promising strategy for alleviating the reductions in growth and EO quality induced by salinity, supporting its potential use in cultivating medicinal plants in salt-affected areas.