Effects of elicitors on some morphological and phytochemical traits of Dracocephalum moldavica L. under low irrigation stress

The use of elicitors to produce the environmentally friendly biological products and in conjunction with the modern agriculture can increase the qualitative and quantitative growth of plants and reduce the effects of environmental stresses on them. To investigate the effects of biostimulants under the low irrigation stress on the morphological and phytochemical characteristics of Dracocephalum moldavica L., a factorial experiment was conducted in a completely randomized block design in the Zanjan University research farm in three replications in 2019. The main factor was the irrigation (100 and 70% of field capacity) and the sub-factor was the foliar application of elicitors including saffron extract (0.01 and 0.05%), ginseng extract (0.5 and 1%), amino acid L-cysteine (50 and 100 μM), and control treatment (no foliar application) at the four-, eight-, and twelve-leaf stages. The morphological and phytochemical traits were evaluated at the 90% flowering stage of the plants. In the present experiment, the highest amount of total chlorophyll (35.68 mg / g FW), carotenoids (9.18 mg / g FW), and relative leaf water content (83.20%) was obtained under the full irrigation conditions stimulated by the 50 μM L-cysteine treatment. While under the water stress conditions, the highest content of total phenols (33.17 mg GA / g DW), total flavonoids (1.53 mg QE / g DW), and antioxidant capacity (95.37%) was obtained in the no foliar application of elicitors treatment. The highest essential oil percentage (0.38%) was observed in the 100 μM L-cysteine treatment under the full irrigation conditions. Although the morphological parameters of D. moldavica had their highest values under the full irrigation conditions, the low irrigation stress led to the synthesis of higher amounts of phenolics and flavonoids and the stronger antioxidant capacity.