www.scholarsresearchlibrary.com t Available online a Scholars Research Library Annals of Biological Research, 2012, 3 (12):5744-5747 (http://scholarsresearchlibrary.com/archive.html) ISSN 0976-1233 CODEN (USA): ABRNBW 5744 Scholars Research Library Evaluation of Bread Wheat Recombinant Inbred Lines under drought conditions Saeid Aharizad* 1 , Abbas Karimi Fard 1 , Seyed Abolghasem Mohammadi 1 and Saeed Sedaghat 2 1 Department of Plant Breeding and Biotechnology, Faculty of Agriculture, University of Tabriz, Tabriz, Iran. 2 Division of Genetics, Department of Biology, Faculty of Science, University of Isfahan, Isfahan, Iran _____________________________________________________________________________________________ ABSTRACT To analyze genetic diversity and to estimate heritability and genetic gain of bread wheat recombinant inbred lines (RILs), 79 RILs derived from a cross between a commercial variety Yecoro Rojo and NO.49 an Iranian local genotype were assessed using square lattice design under normal and water deficit conditions. Combined analysis of variance revealed significant differences among lines for all the studied traits, whereas line and the irrigation interaction was not significant. Among the measured traits, grain yield, number of spikes per square meter, number of grain per spike, plant height and harvest index showed higher phenotypic and genotypic coefficient of variation. Narrow-sense heritability ranged from 38.04 for number of grain per spike to 86.25 for 1000-grian weight. Expected genetic gain was varied from 7.10% (day to heading) to 29.83% (harvest index). Key words: Bread wheat, Genetic gain, Genetic variability, Narrow-sense heritability, Recombinant inbred line _____________________________________________________________________________________________ INTRODUCTION Bread wheat (Triticum aestivum L.) is the most important cultivated agricultural plant that not only allocating approximately one sixth of arable soil to itself, but also constituting a major part of human’s food [1]. Cultivated land and crop yield of wheat are respectively 6.6 million hectares and 13.4 million tonnes in Iran and 225.4 million hectares and 681.9 million tonnes in the planet Earth [2]. drought stress is a limitation on successfully producing the wheat. According to Pfeiffer et al. [3] regularly around 50% or 230 million ha wheat cropland is annually affected by drought conditions. Therefore, genotypes of wheat which are tolerable to drought stress can be selected to increase the productivity in some regions [4]. In order to produce and select productive strains, genetic resources and the information on major traits' genetic parameters should be available. Heritability is regarded as one of the genetic parameters used to determine the breeding methods, which is also indicative of phenotype and genotype adaptation degree [5]. The additive genetic variance portion is important for genotype selection; as in successful selection, it is essential for the additive variance portion to be high enough in genetic variance (narrow-sense heritability) [6]. Simple phenotypic selection can be used in traits showing high heritability [7]. However, high heritability is not sufficient for selection in generations unless it is accompanied by an increase in genetic gain [8]. Manal [9] found rather high heritability in “day to heading”, “spike length” and “1000 grain weight”. Soylo [10] reported low heritability for narrow-sense heritability of “number of spikes per square meter” and “number of grains per spike”. By evaluating wheat doubled haploid lines, Heidari et al. [11] showed high narrow-sense heritability and genetic gain of selection for plant height, 1000 grain weight, and harvest index. The purpose of this research is to investigate