تاثیر تیمارهای مختلف آبیاری روی صفات فیزیولوژی و بیوشیمیایی گیاه داروئی خار مریم (silybum marianum)

تنش کمبود آب رفتار گیاهی را از طریق تاثیر بر متابولیسم گیاهی تغییر داده و بنابراین تاثیر زیادی در تولیدات گیاهان دارد. به منظور ارزیابی تاثیر تنش خشکی روی صفات فیزیولوژی و بیوشیمیایی گیاه خار‌مریم، تیمارهای 100 درصد، 75 درصد، 50 درصد و 25 درصد نیاز آبی گیاه در گلخانه شهرستان هیرمند روستای شندل بر گیاه اعمال و برداشت در مراحل مختلف شامل 6 و 13 هفته بعد از کاشت انجام و صفاتی نظیر وزن خشک، وزن تر، میزان کلروفیل a، کلروفیل b، کاروتنوئید، پروتئین، پرولین و میزان فعالیت آنزیم‌های آنتی‌اکسیدانی مورد سنجش قرار گرفت. نتایج تجزیه واریانس تفاوت معنی‌داری در اثر زمان برداشت، سطوح مختلف آبیاری و اثر متقابل زمان برداشت و سطوح مختلف آبیاری نشان داد. میزان کاروتنوئید با افزایش شدت تنش در هر دو مرحله برداشت شروع به کاهش کرد. میزان کلروفیل a در مرحله 6 هفته بعد از کاشت، کمتر از 13 هفته بعد از کاشت بود ولی در هر دو مرحله، با افزایش تنش میزان آن کاهش پیدا کرد. میزان پروتئین و پرولین نیز با افزایش شدت تنش افزایش یافت. میزان فعالیت آنزیم‌های آنتی‌اکسیدانی نیز با افزایش شدت تنش افزایش یافت، بطوری که در شرایط 100 درصد نیاز آبی‌ کمترین مقدار و در شرایط 25 درصد نیاز آبی به حداکثر مقدار رسید. نتایج این تحقیق ثابت کرد که گیاه خارمریم سازگاری خوبی به تنش خشکی داشته که احتمالاً به دلیل کاهش صدمات اکسیداتیو با القای سیستم آنتی‌اکسیدانی و تجمع اسمولیت‌هایی نظیر پرولین و پروتئین می باشد که این تغییرات نوعی سازگاری به شرایط تنش محسوب میشود.

the effect of various irrigation methods on physiology and biochemical traits of milk thistle (silybum marianum)

introduction: milk thistle contains flavonolignan silymarin in its fruits, making it one of the most important medicinal plants for protecting the liver and treating a variety of liver diseases, such as hepatitis and liver diseases containing toxins. the drought resistance mechanisms of medicinal plants, such as milk thistle, are of critical importance. the investigation of the effect of drought stress on the activity of antioxidant enzymes will aid in the identification of these mechanisms. water stress modifies plant behavior via its effect on plant metabolism and consequently has a substantial effect on plant production. the biosynthesis pathway of secondary metabolites is altered by environmental stresses, altering the production and concentration of active substances in plants. in addition to playing a crucial role in defense mechanisms, secondary metabolites are an important source of bioactive compounds. however, flavonoids not only have antioxidant activity via the release of free radicals, but they also regulate cellular pathways in the defense of plants against environmental stresses, alter plant metabolism, and have a significant impact on plant production.materials and method: in order to determine the effect of drought stress on the physiological and biochemical characteristics of milk thistle, treatments of 100%, 75%, 50%, and 25% water requirement were applied in a greenhouse in the village of shandel, city of hirmand. there were multiple harvesting stages, including 6 and 13 weeks after planting. measurements included dry weight, fresh weight, chlorophyll a, chlorophyll b, carotenoids, proteins, proline levels, and antioxidant enzyme activity. first, the data were examined for normality in minitab software version 18, using the smearnof columnograph method to determine data normality, and then the errors were examined for normality to confirm data normality. then, analysis of variance of all traits and comparison test of duncan were performed at 5% level with sas software version 9.2 (sas 2010).results and discussion:  the analysis of variance revealed significant differences in harvest time, irrigation level, and the interaction between harvest time and irrigation level. in both harvest stages, the concentration of carotenoids began to decrease as the level of stress increased. the amount of chlorophyll a at the stage 6 weeks after planting was less than at the stage 13 weeks after planting, but its amount decreased with increasing stress at both stages. the levels of protein and proline also increased as the level of stress increased. the activity of antioxidant enzymes also increased as the intensity of stress increased, to the point where 100% of water requirements reached the minimum value and 25% reached the maximum value. due to the fact that most oxidative enzymes in this study increased in response to stress, it can be concluded that catalase, superoxide dismutase, guaiacol peroxidase, polyphenol oxidase, and ascorbate peroxidase can eliminate ros in this plant. therefore, milk thistle has a good adaptation to drought stress, which is likely due to the reduction of oxidative damage caused by the activation of the antioxidant system and the accumulation of osmolytes such as proline and protein. these modifications are a form of adaptation to stress conditions.conclusion: the majority of traits were affected by growth stage and stress level.