Background: The use of organic and biological stimulants at different stages of plant growth may increase growth and yield of plants in addition to reducing environmental stresses.
Objective: The aim of this study was to determine the induction effect of various formulations of chitosan, humic acid, and nicgtric acid on nepetalactone content and biochemical traits in catnip.
Methods: This study, which was based on a completely randomized design (CRBD), was conducted in the research greenhouse of Medicinal Plants Research Institute, ACECR. Treatments consisted of: control, citric acid, different concentrations of humic acid, dual combinatorial formulations of chitosan and citric acid, and triple combinatorial formulations of chitosan, citric acid, and humic acid. First, the roots of the transplants were treated before being transferred to the pot. Then, about 20 days after planting, treatments were sprayed on the plants three times – once every15 days.
Results: Results showed that the induction of different formulations of humic acid, citric acid, and chitosan had significant effects on plant height (P≤0.05), the number of lateral branches, the number of leaves, dry weight of leaves, stems, and shoot, content of soluble sugar, phenols, tannins, flavonoids, and nepetalactone (P≤0.01). The highest amounts - in most morpho-physiological traits - were observed 400 ppm chitosan + 800 ppm humic acid + 400 ppm citric acid treatment. The maximum content of nepetalactone was obtained at 200 ppm chitosan + 800 ppm humic acid + 400 ppm citric acid.
Conclusion: The use of biostimulants formulation including humic acid, citric acid, and chitosan had a significant positive effect on improving vegetative characteristics and especially on phytochemical traits of catnip (Nepeta cataria L.).

Background: In sustainable agriculture, reduction of chemical fertilizers- induced environmental pollutions is mainly considered. Therefore, recently application of organic fertilizers particularly their foliar applications received increased attention. Besides, herbal medicine with higher antioxidant activity will be able to limit the formation of free radical species. Objective: Therefore, we aimed to determine the effect of foliar application of organic fertilizers on antioxidant activity and polyphenolic compounds of Marrubium vulgare L. in greenhouse experiment. Methods: In a completely randomized design experiment with three replications that was carried out in 2019, the applied treatments consisted of four levels (0, 250, 500, and 1000 mg L^-1) of foliar application of humic and fulvic acids (0, 250, 500, and 1000 mg L^-1). Some phenolic compounds including gallic acid, chloregenic acid, coumarin, hesperidin, and eugenol were detected and quantified in the Marrubium vulgare L. extracts. Results: Application of 250 mg humic acid L^-1 resulted in the highest extraction of phenolic compounds, coumarin, reducing this content at a higher applied level and by fulvic acid addition. As such, the foliar application of low concentrations of humic acid before the flowering stage was a useful and effective method to increase the synthesis of phenolic compounds. Among the studied organic acids, the application of 250 mg humic acid L^-1 showed the highest antioxidant activities. These compounds can be effective in controlling diseases with free radicals. Conclusion: Based on the findings of the present research, a more appropriate management of the growth and propagation of medicinal plants and their quality can be applied. In addition, humic substances application reduces the chemical fertilizers used, thereby maintaining the environment.