Investigating the Effect of Jasmonate and Lead on some Physiological and Biochemical Traits of Dracocephalum Moldavica L. under the Application of Vermicompost

In recent years, heavy metal pollution has been one of the basic problems of the environment and the production of agricultural and medicinal plants that compounds such as jasmonate in plants can be effective in modulating this stress. In order to investigate the effect of jasmonate and lead on some physiological and biochemical traits of the medicinal plant Dracocephalum Moldavica L. under the application of vermicompost, a factorial experiment was conducted in the form of a completely randomized design with three replications. The treatments included lead at five levels (0, 100, 200, 300, and 400 mg/kg soil) and jasmonate at four levels (0, 50, 100, and 150 mmol L-1) in the conditions of non-application and application of 10 tons per hectare of vermicompost. The traits investigated in this experiment included fresh and dry weight of shoot and root, the ratio of shoot to root dry weight, leaf area and the amount of carbohydrate, proline and  catalase in plant leaves. The results showed that in the vegetative growth stage of Dracocephalum Moldavica, with increasing jasmonate concentration, the fresh and dry weight of shoot and root increased, so that the highest amount of fresh and dry weight of shoot, dry weight of root and total weight of the plant was obtained in 150 mmol L-1 jasmonate treatment. In both vegetative, and reproductive stages, different levels of lead had a significant effect on the fresh and dry weight of vegetative organs, and with the increase in lead up to 300 mgkg-1, fresh and dry weight of shoot, root and fresh weight of the whole plant, showed a significant decreasing trend. The application of vermicompost also significantly increased the fresh and dry weight of shoot, the dry weight of the root and the fresh weight of the whole plant in the reproductive stage. With the increase of jasmonate levels, the amount of leaf carbohydrate first showed an increasing trend and then decreased. Also, with the increase in lead concentration, the average carbohydrate signifi cantly increased. With the increase in the amount of applied jasmonate, the average leaf proline also decreased at first, but at higher levels, the value of this parameter showed an increasing trend. Also, with the increase in lead level, the average leaf proline found a significant non-linear increasing trend. In general, the investigation of the triple effect of jasmonate, lead, and vermicompost on the studied traits showed that the highest amount of carbohydrate and proline in the vegetative growth stage were respectively in combined treatments of 100 mmol.l-1jasmonate, 200 mg.l-1 lead without applying vermicompost and 0 mmol.l-1 jasmonate, 400 mg.l-1 lead without applying vermicompost was obtained. In the reproductive growth stage, the highest amounts of carbohydrate and proline were obtained in the combined treatments of 0 mmol.l-1 jasmonate, 300 mg.l-1 lead without applying vermicompost and 150 mmol.l-1 jasmonate, 100 mg.l-1 lead without applying vermicompost. In general, in the mean of investigated lead levels with the increase of jasmonate and the application of vermicompost, the amount of lead in the plant organs showed a decreasing trend.