پاسخ ژنوتيپ هاي گياه خارمريم (Silybum marianum L.) به تنش كم آبي، تغذيه برگي سولفات پتاسيم، تاريخ كاشت و افزايش غلظت دي اكسيدكربن

This research was conducted to investigate the effects of drought stress, potassium sulfate foliar application, elevated air carbon dioxide, an‎d planting date on milk thistle (Silybum marianum L.), a highly valuable plant due to its medicinal properties an‎d having grains rich in silymarin. The study was carried out in the form of three separate experiments during the years of 2019 to 2021 at the research farm an‎d greenhouse of Isfahan University of Technology. In the first experiment, ten milk thistle genotypes (Alborz, Isfahan, Omidiyeh, Shushtar, Sari, Charam, Hungary, Mashhad, Najafabad, Yazd) were eva‎luated under three irrigation regimes (based on depletion of 40, 60, an‎d 80% available water) an‎d two levels of potassium sulfate. Water stress increased the concentrations of proline, soluble carbohydrates, malondialdehyde, phenol, flavonoid, silymarin, an‎d the activity of antioxidant enzymes were, while decreased relative leaf water content, quantum efficiency of photosystem II, chlorophyll an‎d carotenoid contents, shoot dry weight, an‎d the yields of grain, oil, an‎d silymarin. The lowest reduction in grain yield was observed in Hungary genotype at irrigation treatment based on 60% water depletion, whereas at irrigation based on 80% available water depletion, it was observed in the Shushtar genotype. The highest increase in silymarin content under water stress belonged to Mashhad. potassium foliar application decreased the concentrations of proline, soluble carbohydrates, phenol, flavonoid, an‎d silymarin, while increased relative leaf water content, quantum efficiency of photosystem II, DPPH, chlorophyll an‎d carotenoid contents, shoot dry weight, an‎d grain an‎d oil yields. The highest increase in grain yield due to potassium foliar application was obtained in Isfahan, Mashhad, an‎d Yazd genotypes, respectively at irrigation treatments based on 40, 60 an‎d 80% water depletion. In the second field experiment, four milk thistle genotypes (Isfahan, Omidiyeh, Charam, an‎d Hungary) were eva‎luated under three irrigation levels based on 40, 60, an‎d 80% depletion of available water under five planting dates including September 27, October 17, November 6 an‎d 26, an‎d March 10. Water stress increased the concentrations of proline, soluble carbohydrates, the activity of antioxidant enzymes, but decreased relative leaf water content, quantum efficiency of photosystem II, chlorophyll an‎d carotenoid contents, plant height, growing degree days to flowering an‎d maturity, number of flowers per plant, shoot dry weight, an‎d grain yield. The lowest reduction in grain yield was observed in Omidiyeh, an‎d the highest yield belonged to Isfahan an‎d Charam under planting date of October 17. The greatest increase in the activity of ascorbate peroxidase enzyme under water stress was observed in the Omidiyeh, indicating the role of this enzyme in the drought tolerance of this genotype. In greenhouse experiment, four milk thistle genotypes were eva‎luated under three irrigation levels based on 40, 60, an‎d 80% depletion of available water an‎d two carbon dioxide concentrations (400 an‎d 700 µmol mol⁻¹). Elevated carbon dioxide concentration decreased the concentrations of proline, malondialdehyde, chlorophyll, carotenoids, phenols, an‎d flavonoids, antioxidant enzyme activity, an‎d quantum efficiency of photosystem II, while increased relative leaf water content, soluble carbohydrates, plant height, root an‎d shoot dry weight, grain yield, oil percentage an‎d yield, an‎d silymarin percentage. The highest increase in grain yield due to increased carbon dioxide concentration was observed in Hungary. The results of this study showed that significant variation exists among milk thistle genotypes in terms of their response to water deficit, potassium fertilizer, an‎d elevated air carbon dioxide concentration.

حميدرضا عشقي زاده , مرتضي زاهدي

محمد مهدي مجيدي , مهدي قيصري

حسن كريم مجني , مريم حقيقي , محمود رضا تدين