بررسی تاثیر بافت های مختلف خاک بر خصوصیات مورفولوژیکی و میزان اسانس گیاه دارویی به‌‌لیمو (lippia citriodora)

این پژوهش با هدف بررسی اثر بافت‌های مختلف خاک بر روی رشد و میزان اسانس گیاه دارویی به‌ لیمو به منظور انتخاب بهترین نوع بافت خاک جهت پرورش و اسانس گیری در شرایط گلخانه در سال زراعی 1397-1398 انجام شده است. بدین منظور آزمایش در قالب طرح بلوک های کاملا تصادفی و در سه تکرار به اجرا در آمد. تیمارهای مورد آزمایش شامل چهار نوع بافت خاک لومی، شنی لومی، شنی، لوم رسی سیلتی بودند. نتایج نشان داد که تاثیر نوع خاک بر میزان اسانس گیاه به لیمو در سطح یک هزارم (p≤0.001)؛ بر ارتفاع گیاه و حجم ریشه در سطح یک درصد (p≤0.01) و در سطح پنج درصد هم بر ضخامت ساقه، تعداد برگ هر بوته و وزن خشک برگ اثرات  معناداری از خود نشان داده است (p≤0.05). نتایج ضرایب همبستگی پیرسون نشان داد ارتباط مثبت و  معناداری بین بافت های مختلف خاک و صفات اندازه گیری شده وجود دارد؛ بالاترین همبستگی مربوط به طول ریشه و سطح برگ به ترتیب با ضریب 0/89 و 0/80 مشاهده شد (p≤0.01). نتایج مقایسۀ میانگین ها برای بررسی تاثیر بافت خاک بر درصد اسانس گیاه دارویی به ‌‌لیمو نشان داد که، در بافت لوم رسی سیلتی بیش ترین درصد اسانس وجود دارد و کم ترین آن مربوط به بافت خاک شنی است. با توجه به نتایج بدست آمده گیاه به‌ لیمو برای رشد و نمو از نظر مواد غذایی مورد نیاز در حد متوسط است. از آن جایی که مقدار برگ تولیدی گیاه به لیمو در خاک لومی و لومی شنی از سایر بافت ها بیشتر گزارش شد؛ بنابراین، بافت لومی و لومی شنی جهت کشت گیاه دارویی به ‌‌لیمو به منظور رسیدن به بهترین نتیجه توصیه می گردد.

investigating the effect of different soil textures on morphological characteristics and the amount of essential oil of lippia citriodora medicinal plant

introduction the physical properties of soil are essential because of their role in supporting plant growth. these characteristics determine how the plant interacts with the soil, absorption of water and nutrients, root penetration, soil temperature, and the activity of microorganisms. among the physical properties of soil, soil texture has a significant impact. on the other hand, with the increase in the population and the pharmaceutical industry’s need for medicinal plants as the primary raw material for drug production, attention and research on the lippia citriodora plant are essential. l. citriodora is effective in treating colds, asthma, colic, fever, diarrhea, dyspepsia, insomnia, and anxiety. l. citriodora tea is relaxing and soothing to the nerves. its analgesic, antiinflammatory, and antioxidant effects have been proven. plants containing essential oil, such as l. citriodora may differ in yield and quality of oil according to the type of soil texture, so in order to achieve the highest yield of essential oil and the best quality, the soil should be adapted to the type and needs of the plant for better growth and development be provided. therefore, the purpose of this research is to investigate the effects of different soil textures on the growth and development and the amount of essential oil of l. citriodora in greenhouse conditions. materials and methodsthis research has been carried out in pots in the research greenhouse of yazd university in the crop year of 20172018. the experiment was conducted as a randomized complete block design in three replications for five months. plastic pots with drains of 18 heights, opening diameter of 17 cm, and drain diameter of one cm were used for growing seedlings. the pots with different soil textures (loamy, sandy loam, sand, and silty clay loam) based on the calculation of the weight percent of soil moisture at the field capacity (fc) were irrigated. the length of the stem and roots were measured with a ruler with mm accuracy. a caliper was used to measure the thickness of the stem. the samples of shoots and roots were kept in an oven at 70 °c for 48 hr. a digital scale with an accuracy of 0.001 gr was used to measure the dry weight of the shoots and roots of the plants. in order to measure the root volume after separating and washing the roots, the roots of each replicate were placed inside a graded cylinder with a certain amount of water, and the volume of the root was measured in mm based on the change in the water volume inside the cylinder. to measure the plant leaf surface, five leaves of different sizes were randomly separated from each repetition and different parts of the plant, and using the adc bioscienticltd model (am200) device, the total surface size of each of five leaves was measured in each repetition. the essential oil of l. citriodora was extracted by distillation method with water from a cloninger machine. in this way, in order to increase the contact surface of the water with the plant in the process of extracting essential oils, first the dry leaves of the l. citriodora, were turned into powder by an electric mill and immediately transferred into a 2000 ml flask, then 500 ml of water was added to it. after boiling in water for three hr, the heat source was cut off and the resulting essential oil was poured into opaque glass containers and stored in a refrigerator at 4 °c. to check the statistical effects of each treatment on the study variables, the normality of the data was checked using the kolmogorovsmirnov test at the 95% confidence level. oneway analysis of variance (anova) was also used and duncan’s test was applied to compare means. pearson’s correlation method was performed to check the correlation between soil texture and measured traits. results and discussion the results showed the significant effects of soil type on the amount of l. citriodora essential oil (p≤0.001).