Deficiency of water can enhance root respiration rate of drought-sensitive but not drought-tolerant spring wheat

Root respiration was measured in vivo by infrared gas analysis of complete root systems in drought-sensitive (Longchun 8139-2) and drought-tolerant (Dingxi 24) spring wheat (Triticum aestivum) cultivars. Plants were grown in sand culture for 3 weeks under the following regimes: (a) water sufficiency, (b) moderate drought stress or (c) severe drought stress. The aim was to study the acclimation to drought stress in terms of changes in root growth, root respiration and energy requirement for water uptake. Drought stress increased the root:shoot ratio of both varieties. Roots of water-sufficient treatments respired 4.03 and 2.87 mg glucose h(-1) g(-1) in Longchun 8139-2 and Dingxi 24, respectively. However, severe drought stress enhanced root respiration of Longchun 8139-2 and Dingxi 24 to 6.52 and 3.01 mg glucose h(-1) g(-1), respectively. Compared with water-sufficient plants, drought-sensitive spring wheat (Longchun 8139-2) used a relatively higher amount of glucose to absorb water in drought stress treatment, especially in severe drought stress. The drought-resistant spring wheat Dingxi 24 used lower amount of glucose to absorb water in drought stress conditions, relative to drought-sensitive plants. In the arid and semi-arid region of the Losses Plateau, drought-resistant wheat species have many advantages over drought-sensitive species. (C) 2003 Elsevier B.V. All rights reserved.