International Journal of Agriculture and Crop Sciences. Available online at www.ijagcs.com IJACS/2013/5-14/1601-1605 ISSN 2227-670X ©2013 IJACS Journal Evaluation of the advanced cultivars and lines of wheat bread in cutting irrigation condition at flowering stag by using the drought tolerance indices in Sistan region Musa Ramroodi 1 , Reza Baradaran 2 , Mohammad hossein Saberi 3, Mohammad Reza Naroui Rad 4 1. The branches management of the agricultural bank in Zahedan, Danesh three-way, University Avenue, Zahedan, Iran. 2. Assistant Professor, University of Birjand 3. Faculty Member of Agricultural and Natural Resources Research Center of Birjand 4. Faculty Member of Agricultural and Natural Resources Research Center of Sistan Corresponding author email: MR1349@YAHOO.COM ABSTRACT: In order to examine the effect of drought stress on cultivars and lines of ten wheat cultivars and also to introduce the genotypes which are tolerant and susceptible to drought, two separate experiments (normal and under stress) were performed in a randomized complete block design with three replications in research site of the Zabol Agricultural Research Center located in zahak city on agricultural season of 2007-2008. In the first experiment, the stress imposed and irrigation were cut off at the time of 50% flowering stage; but in non-stress experiment, a typical regional irrigation was done till the end of growing season and grain yield was measured at harvest time. The Analysis results of variance for traits under drought stress showed a significant difference between the traits of both normal and under stress conditions. To identify the genotypes tolerant to stress, five indices were used: Mean productivity (MP), geometric mean productivity (GMP), tolerance (TOL), stress susceptibility index (SSI) and stress tolerance index (STI). The MP, GMP and STI indices were highly correlated with grain yield under stress and non-stress conditions. Therefore; this indices can be used for selection of the tolerant genotypes. By considering the indices, the Kauz and Chamran-6 cultivars were identified as the most tolerant cultivars. Key words: wheat cultivars, Seed yield, Tolerance index, Susceptibility index INTRODUCTION Target of the yield comparing experiments is to select genotypes that are adapted to the stress and non-stress conditions, and varieties which are selected for high yield in non-stress condition may not have much yield under stress condition. In fact, a variety which is tolerant to stress should be evaluated in stress condition before being selected (Fernandez. 1992). Fischer and Maurer (Fischer and Maurer, 1978) have introduced the stress susceptibility index (SSI) to recognize genotypes which are susceptible and non- susceptible to stress so based on this method, the SI index is derived according the ratio of mean yield under stress condition to yield under non-stress condition, and then the stress susceptibility index is calculated by a special formula. To select the tolerant and susceptible genotypes from the tolerance indices, the geometric mean and STI were proposed (Fernandez. 1992), and the TOL index in form of subtraction between the mean yield in stress and non-stress conditions, and the MP index in form of mean average yield in both normal and drought-stress conditions were proposed by Rosielle and Hamblin (Roselle and Hamblin, 1981). Fernandez (Fernandez, 1992) classified the genotypes in four groups based on their responses to the environmental stress or non-stress conditions. Different indices have been introduced to evaluate the genotypes response in different environmental conditions and to determine their susceptibility and resistance. From these indices the tolerance index (TOL 1 ), mean productivity index (MP 2 ),