Response of antioxidative defence system to temperature and water stress combinations in wheat seedlings

The effects of environmental stress combinations on soluble metabolic compounds were investigated in Triticum aestivum L. (cv. Bezostaya-1, cv. Seri-82, cv. Kirac-66) and Triticum durum Desf. (ev. Kiziltan-91, ev. Kunduru 414-44, ev. C.1252). The seedlings were grown at normal (24/16 degreesC), low (LT, 5/-5 degreesC) and high (HT, 40/30 degreesC) temperature conditions and then exposed to waterlogging, drought and salinity (0.7% NaCl) stresses. Seedlings responses to cross interactions between temperature and water stresses were investigated. Root and shoot elongation significantly decreased under drought and salt stresses. LT and HT treatment supported the growth inhibition observed in the seedlings under salt stress. The LT stress increased the total ascorbic acid (TAA) content, catalase (CAT, EC 1.11.1.6) and glutathione reductase (GR, EC 1.6.4.2) activities. The HT stress increased the carotenoids and GR activities. The content of alpha-tocopherol significantly increased under drought and salt stresses but significantly decreased under HT stress. While CAT activity decreased especially in T durum genotypes, GR activity increased under the HT stress. It is concluded that the effects of temperature stresses on antioxidative defence system may be altered by water-salt stress. (C) 2002 Elsevier Science Ireland Ltd. All rights reserved.