The effect of soil properties and manure application on morphological characteristics and quality of peppermint (Mentha piperita L.) medicinal plant

  In addition to the genetic effects on the morphological characteristics and quality of the medicinal plants, environmental factors have an important role on the plant growth and their quality. Soil properties have effect on the characteristics of medicinal plants. Unfortunately, investigation of the effect of soil properties and manure application on the morphological characteristics of medicinal plants is rarely considered. Therefore, the main objective of the present study was to find out the effect of the different soil properties and manure application on the morphological characteristics and quality of peppermint (Mentha piperita L.). The pot experiment was performed as a factorial in a randomized complete block design (RCBD) with three replications. Factors were consisting of three soils series (Chaharmahal, Boldaji and Sefid-dasht) of Shahrekord plain in Chaharmahal-Va-Bakhtiari Province and two levels of control (no application of animal manure) and application of animal manure (147 g per pot equal to 30 ton/ha). Firstly, the soil physicochemical properties were determined and after the cultivation period, the vegetative characteristics, plant yield, essential oil content and yield were measured. The results showed that the effect of soil, animal manure and their interaction on leaf length and width, number of leaf per stem, stem height, leaf fresh and dry weight, stem dry weight, biological yield and essential oil yield were significant at 1% probability level in both cutting. Also, means comparison showed significant differences between different soils. The sefid-dasht soil with more phosphorous, soluble magnesium and K and less calcium carbonate equivalent caused increase in growth, biological yield and essential oil yield in both cuttings. Moreover, fertilization had a positive and significant effect on the leaf length and width, leaf number per stem, leaf fresh and dry weight, biological yield and essential oil percentage and yield. Means comparison of interaction showed that the most biological yield and essential oil yield were obtained in sefid-dasht soil and usage of manure in both cuttings. The results showed that morphological characteristics and quality of peppermint (Mentha piperita L.) were statistically different at the studied soil series. Also, results demonstrated that the Sefid-dasht and Boldaji soil series have the highest and lowest potential for peppermint (Mentha piperita L.) production, respectively. Moreover, fertilization had a positive and significant effect on the leaf length and width, leaf number per stem, leaf fresh and dry weight, biological yield and essential oil percentage and yield.
Keywords: Soil series, Peppermint, Manure, Morphological characteristics, Essential oil