Effect of phenylalanine and gamma-aminobutyric acids on morphophysiological characteristics of Dracocephalum moldavica L. under salinity stress

Salinity is one of the most important environmental stresses that diminishes the growth and yield of crop plants. Application of biological fertilizers, especially amino acids, is important to overcome this issue in order to improve the growth, quantity and quality of the products. In order to investigate the effect of amino acids on some morphophysiological characteristics of the medicinal plant Dracocephalum moldavica grown under salinity stress, a factorial experiment was conducted in a randomized complete block design (RCBD) with three replications in the greenhouse of the University of Zanjan, during Autumn of ۲۰۲۲. The experimental treatments included three levels of salinity (۰, ۴۰ and ۸۰ mM NaCl) as the main plots and phenylalanine (۲ and ۴ mM), gamma aminobutyric acid (GABA ۵ and ۱۰ mM) plus control were used as subplots. The results showed that with increasing salinity, some morphological and physiological parameters of the plant decreased, but the anthocyanin content of the flower increased. The use of ۲ mM phenylalanine significantly increased the FW and DW of the plant, and the use of ۴ mM led to a significant increase in the number of leaves, cell membrane stability index, chlorophyll and carotenoid at ۰ mM and anthocyanin in the condition of ۸۰ mM sodium chloride. Also, ۵ and ۱۰ mM GABA in non-stress conditions and ۲ mM phenylalanine in ۴۰ and ۸۰ mM salinity conditions led to an increase in stem diameter. Although the application of ۴ mM phenylalanine had the greatest effect in non-stress conditions, GABA ۱۰ mM in salt stress conditions had a more effective role in increasing the FW and DW of the plant, chlorophyll, and carotenoid content, and as a result, increasing the stability of the cell membrane. Therefore, the use of different levels of the amino acids ۴ mM phenylalanine and ۱۰ mM GABA is recommended to improve the growth and development pattern and physiological characteristics of the Dracocephalum moldavica L. plant.

Keywords:

Photosynthetic pigments , Membrane stability index , Relative leaf water content , Amino acids , رنگیزه های فتوسنتزی , شاخص پایداری غشاء , محتوای نسبی آب برگ , اسیدهای آمینه