African Journal of Agricultural Research Vol. 5(20), pp. 2829-2836, 18 October, 2010 Available online at http://www.academicjournals.org/AJAR ISSN 1991-637X ©2010 Academic Journals Full Length Research Paper Evaluation of yield potential and stress adaptive trait in wheat genotypes under post anthesis drought stress conditions Amirgholi Sanjari Pireivatlou 1 *, Bahram Dehdar Masjedlou 1 and Ramiz T. Aliyev 2 1 Agricultural and Natural Resources Research Station, Ardabil-Islamic Republic of Iran. 2 Genetic Resources Institute, Azerbaijan National Academy of Science, Republic of Azerbaijan. Accepted 6 September, 2010 Twenty winter wheat genotypes were evaluated under both post-anthesis drought stress and normal conditions in Ardabil Agricultural Research Station in two successive growing seasons 2005 - 2007 using randomized complete block design with three replications. The results showed that there were significant differences between genotypes in stem reserve under both normal and post anthesis drought stress conditions. Post-anthesis drought stress did not affect kernel numbers per spike. The rate of dry matter accumulation by kernels considerably decreased by water deficit. Dry weight of vegetative organs decreased in grain filling period under stress and normal conditions, contrasting anthesis stage. But, the rate of translocated dry matter was much higher in genotypes nos. 14, 15, 16, 18, 19 and 20 under drought stress condition. 1000 GW and weight of kernels per spike were more severely reduced by water deficit. The positive correlation of grain yield with grain weight per spike, 1000 GW, remobilization of dry matter, harvest index and stress tolerance index (STI) and significant negative correlation of grain yield with drought susceptibility index (SSI) revealed that selection must be exercised for high harvest index, grain weight per spike, 1000 GW, remobilization of dry matter and STI in stress condition. The negative correlation of ‘STI’ with ‘SSI’ indicated the efficiency of ‘STI’ as a selection criterion for identifying the drought tolerant with high yield potential in winter wheat genotypes. Key words: Winter wheat, drought stress, dry matter, remobilization. INTRODUCTION In semi-arid areas of the world with a Mediterranean climate, rainfall decreases as soil evaporation increases in spring when bread wheat (Triticum aestivum L.) enters the grain-filling period (Ehdaie et al., 2006). Wheat crops often experience water deficit and heat stress during grain growth and development, which limit productivity (Ehdaie et al., 1988; Ehdaie and Waines, 1989). Wheat is grown on 6.9 million ha in Iran (Anonymous, 2003). About 36% of that is in irrigated and 64% in rainfed areas. Approximately 50 - 55% of wheat grown areas are planted by winter and facultative wheat varieties. Most winter wheat are grown under varied rainfed and water stressed conditions in the semiarid cold climate of Iran. *Corresponding author. E-mail: amirgholis@yahoo.com. Year–to-year fluctuations in the amount (annual precipitation ranges between 280 – 300 mm), frequency and duration of rain is high. Other factors such as low temperature in winter (absolute minimum temperature is –30ºC), high temperature during the terminal grain filling period (+35ºC) and post-anthesis water deficit conditions in irrigated wheat, influence crop growth and yield (Sanjari, 2001). Grain growth and development in wheat depend on C from three sources: Current assimilates produced by photosynthesis in leaves and stems, mobilization of the stored carbohydrates and N containing compounds within these organs and their subsequent transport to the spike and growing kernels, and assimilates produced by the spike (Bradfor and Hasio, 1982). Under terminal drought, there is a rapid decline of photosynthesis after anthesis that limits the contribution of current assimilates to the grain (Johnson et al., 1981).