Effect of Organic Fertilizers and Salicylic Acid on Growth Traits, Flavonoid, Photosynthetic Pigments, and Essential Oil in Dragonhead

The use of manure in sustainable agriculture as a cheap and valuable resource is a common practice. Vermicompost has characteristics such as high cation exchange power, high porosity, high field capacity and is Free of unpleasant odor and pathogens and contains microbial metabolites that act. Salicylic acid (SA), a plant phenolic compound is considered as a plant growth regulator and its role in the defense mechanisms against biotic and abiotic stresses has been well characterized. It can act as a secondary metabolite stimulant in plants. Therefore, its application is an appropriate method for increasing the production of secondary metabolites in medicinal plants and plays an important role in the secondary metabolite production cycle. This study was conducted to investigate the effect of vermicompost, cow manure and different concentrations of salicylic acid on growth traits, essential oil yield and physiological characteristics of medicinal plant dragonhead under Miandoab saline soil. Experiment was carried out in a factorial experiment in a randomized complete block design with three replications.

The experiment was carried out as a factorial experiment in a completely randomized block design with three replications and two fertilizer factors (at three levels manure 30 ton/ha, vermicompost fertilizer 10 ton/ha and control treatment) and salicylic acid (at four levels zero, 5, 10 and 15 mM) were administered. Seeds were prepared from Isfahan Pakan Bazr. seeds were sown in plots 2 m long and 1.5 m wide. Seedlings were thinning in three to four leaf stages after emergence. Salicylic acid treatment was sprayed in three stages, two months after planting and ten days in a row. Irrigation was carried out using a siphon twice a week. In this experiment the traits included plant height, fresh weight of shoot, dry weight of shoot, leaf number, crown diameter, internode length, flavonoid, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid and essential oil yield were measured.

Analysis of variance showed that the effect of organic fertilizer and salicylic acid concentration on measured traits was significant at 1% probability level. Mean comparisons showed the highest plant height, leaf number and chlorophyll a in vermicompost treatment and 1.5 mM salicylic acid. The highest total chlorophyll and carotenoids content was obtained in cow manure and 1.5 mM salicylic acid treatment. and the highest flavonoid content was obtained in cow manure and 0.5 mM salicylic acid treatment. This study showed that organic fertilizer treatment increased the quantitative and qualitative traits of the plant relative to the control treatment, which may be due to the presence of phytohormones in organic fertilizer and high nutrient content, especially important growth elements such as nitrogen, potassium and phosphorus.The slow release of nutrients from organic fertilizers, high soil water storage capacity, increased uptake of nutrients by plants, and overall improved chemical and physical structure of crop yields due to increased crop yields. Organicity has a stimulatory effect on the accumulation of phenolic compounds in plants. The large amount of flavonoids in plants is related to the role of organic fertilizers in the biosynthesis of substances that induce the gastric acetate pathway, thereby producing more flavonoid and phenolics. Therefore, it can be said that in order to reduce the use of chemical inputs and achieve sustainable agricultural goals, part of the nutrient requirement of the plant can be met, especially in saline fields of the Midandab region using organic fertilizers.

The results of this study showed a positive response of the Dragonhead to the application of organic fertilizers and salicylic acid. Therefore, it can be said that in order to reduce the use of chemical inputs and achieve sustainable agricultural goals, part of the nutrient requirement of the plant can be met, especially in unsuitable saline soils such as miandoab saline soils by using of organic fertilizers and salicylic acid.