University of Tehran Press Iranian Journal of Soil and Water Research 2008-479X 51 12 2021 02 19 Investigation of Different Levels of Irrigation on Yield and Water Use Efficiency of Stevia Rebaudiana Bertoni in Greenhouse and Field Environment Conditions Investigation of Different Levels of Irrigation on Yield and Water Use Efficiency of Stevia Rebaudiana Bertoni in Greenhouse and Field Environment Conditions 3115 3125 80437 10.22059/ijswr.2020.308735.668716 FA Houshang Ghamarnia Water Engineering Dept, Faculty of Agricultural Science and Engineering, Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran 0000-0003-2106-1075 Zahra Jalili Water Engineering Department, Faculty of Agricultural Sciences and Engineering, Campus of Agriculture and Natural Resources, Razi University, Kermanshah, Iran Seyed Vahidoddin Rezvani Water Engineering Department, Faculty of Agriculture Engineering, University of Kurdistan, Sanandaj, Iran Journal Article 2020 08 23 Iran, with a mean precipitation of 230 mm per year, is classified as arid and semi-arid region in the world, facing a water crisis. Since, water resources with high quality for irrigation are limited, therefore the use of deficit irrigation as a method for reducing water consumption is essential in the future. Stevia is a plant with medicinal and anti-diabetic effects, native to the mountainous region of Amoeba, located on the border of Brazil and Paraguay, which is widely cultivated in Shiraz and Isfahan of Iran. The diterpene glycosides in this plant (the main cause of the very sweet taste in plant extracts) are up to 300 times sweeter than sugar used in the pharmaceutical and food industries. In the present study, different treatments consist of 40, 60, 80 and 100% of total crop water requirement were carried out to investigate the effects of different water shortage on (<em>Stevia Rebaudiana B</em>.). This experiment was performed in three replications in the greenhouse and farm environment condition in 2016 and 2017.The results showed that the tolerance threshold of stevia in low irrigation to prevent reduced leaf and sugar yield in the greenhouse environment was about (3.2 and 3.1) and (0.94 and 0.83) and in the farm condition was obtained as: (3.3 and 3.1) and (1.12 and 0.98) of defecit irrigation percentage in the first and second year of cultivation respectively. Iran, with a mean precipitation of 230 mm per year, is classified as arid and semi-arid region in the world, facing a water crisis. Since, water resources with high quality for irrigation are limited, therefore the use of deficit irrigation as a method for reducing water consumption is essential in the future. Stevia is a plant with medicinal and anti-diabetic effects, native to the mountainous region of Amoeba, located on the border of Brazil and Paraguay, which is widely cultivated in Shiraz and Isfahan of Iran. The diterpene glycosides in this plant (the main cause of the very sweet taste in plant extracts) are up to 300 times sweeter than sugar used in the pharmaceutical and food industries. In the present study, different treatments consist of 40, 60, 80 and 100% of total crop water requirement were carried out to investigate the effects of different water shortage on (<em>Stevia Rebaudiana B</em>.). This experiment was performed in three replications in the greenhouse and farm environment condition in 2016 and 2017.The results showed that the tolerance threshold of stevia in low irrigation to prevent reduced leaf and sugar yield in the greenhouse environment was about (3.2 and 3.1) and (0.94 and 0.83) and in the farm condition was obtained as: (3.3 and 3.1) and (1.12 and 0.98) of defecit irrigation percentage in the first and second year of cultivation respectively. https://ijswr.ut.ac.ir/article_80437_b5dc8e724f2e2b5fbf61ef9ed7328f44.pdf