Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 45 4 2014 12 22 The impact of barley root structure and physiological traits on drought response The impact of barley root structure and physiological traits on drought response 553 563 53565 10.22059/ijfcs.2014.53565 FA Reza Kesahvarznia Ph. D. Student, Genetics Engineering, University of Tehran 0000-0002-4357-750X Maryam Shahbazi Assistant Professor, Biotechnology Institute of Agricultural Educate Valiolah Mohammadi Associate Professor , University College of Agriculture & Natural Resources, University of Tehran, Karaj 0000-0001-6487-0740 Ghasem Hosseini Salekdeh Associate Professor, Biotechnology Institute of Agricultural Educate, Ali Ahmadi Assistant Professor, University College of Agriculture & Natural Resources, University of Tehran, Karaj 0000-0003-0044-2645 Ehsan Mohseni-Fard Ph. D. Student, Faculty of Agriculture, Ferdowsi University of Mashhad Journal Article 2014 01 12 abstract Drought is the most important factor limiting crop yield word wide. Osmotic adjustment (OA) and strong and deep root system result in increased cereal drought tolerance through increasing water uptake and water use efficiency. The impact of root structure and physiological traits on drought stress response was studied in three barley cultivars including Yousof (drought tolerant), Morocco (susceptible), and Fajr30 (semi-tolerant) and an Iranian accession of wild species, <em>Hordeom spontaneum</em> (tolerant). Seeds were planted in PVC pipes 100 cm depth and 10 cm diameter. Two moisture regimes applied including a normal irrigation at field capacity (control), and drought stress at 20% available water. Root characteristics and physiological traits were measured ar flowering stage. Drought stress reduced stomatal conductivity, RWC, Leaf water potential, osmotic potential, OA and increased leaf temperature. Minimum decline in Leaf water potential, osmotic potential and RWC was observed in tolerant varieties (Yousof and <em>H. spontaneum</em>). The tolerant and susceptible varieties showed the highest and the lowest OA. Drought stress led to reduced root dry weight and volume in all varieties, susceptible variety showing the highest decline. Root depth increased under stress in all tolerant and semi-tolerant cultivars, while decreased in the susceptible one. The results showed that tolerant varieties are varieties which could uptake more water by increasing root depth leading to higher OA and higher RWC. Higher RWC results in more transpiration and lower leaf temperature under stress condition. abstract Drought is the most important factor limiting crop yield word wide. Osmotic adjustment (OA) and strong and deep root system result in increased cereal drought tolerance through increasing water uptake and water use efficiency. The impact of root structure and physiological traits on drought stress response was studied in three barley cultivars including Yousof (drought tolerant), Morocco (susceptible), and Fajr30 (semi-tolerant) and an Iranian accession of wild species, <em>Hordeom spontaneum</em> (tolerant). Seeds were planted in PVC pipes 100 cm depth and 10 cm diameter. Two moisture regimes applied including a normal irrigation at field capacity (control), and drought stress at 20% available water. Root characteristics and physiological traits were measured ar flowering stage. Drought stress reduced stomatal conductivity, RWC, Leaf water potential, osmotic potential, OA and increased leaf temperature. Minimum decline in Leaf water potential, osmotic potential and RWC was observed in tolerant varieties (Yousof and <em>H. spontaneum</em>). The tolerant and susceptible varieties showed the highest and the lowest OA. Drought stress led to reduced root dry weight and volume in all varieties, susceptible variety showing the highest decline. Root depth increased under stress in all tolerant and semi-tolerant cultivars, while decreased in the susceptible one. The results showed that tolerant varieties are varieties which could uptake more water by increasing root depth leading to higher OA and higher RWC. Higher RWC results in more transpiration and lower leaf temperature under stress condition. https://ijfcs.ut.ac.ir/article_53565_e310e4d8a8909c5853aa3a3fbcbc7ea6.pdf