The Effect of Biostimulants based on Free Amino Acids on some Growth and Physiological Parameters of Dracocephalum moldavica L. under Salinity Stress

In arid and semi-arid areas salinity reduces agricultural productivity. Biostimulants based on amino acids promote plant growth and yield while significantly reducing abiotic stresses-related injuries. As a result, current study assessed the effect of biostimulants based on free amino acids on Moldavian balm under salinity stress. A factorial experiment using a randomized complete block design with three replications was done. The plants were imposed with four levels of salinity (0, 20, 40 and 60 mM NaCl) and were treated using four formulations of amino acids (Kadostim, Fosnutren, Humiforte and Aminolforte). The results revealed that increasing the salinity level significantly reduced growth parameters such as fresh and dry weight of biomass, root length, shoot length, secondary branch length, crown diameter, internode number, internode length, secondary branch number, leaf number and biochemical parameters such as RWC, chlorophyll a, b, total and carotenoids while increased some osmolytes such as soluble sugar and proline in root and shoot. Leaf spraying of the bio-stimulates based on amino acids, significantly improved the negative effects of salinity stress on growth and biochemical parameters in Moldavian balm, and among them Kadostim had the most significantly positive effects on morphological and biochemical parameters and followed by Aminolforte.