Evaluation of Bread Wheat (Triticum aestivum L.) Genotypes for Drought Tolerance through Selection Indices Jawed Aslam Khyber 1 , Faiza Soomro 1 , Wahid Dino Sipio 1 , Abdul Wahid Baloch 1 , Jay Kumar Soothar 1 , Mukesh Kumar Soothar 2,3 *, Zahid Ali 4 1 Department of Plant Breeding and Genetics, Sindh Agriculture University Tandojam, Pakistan 2 Farmland Irrigation Research Institute, Chinese Academy of Agricultural Sciences, Xinxiang 453000, China 3 Department of Soil Science, Sindh Agriculture University Tandojam, Pakistan 4 Department of Agronomy, Sindh Agriculture University Tandojam, Pakistan mukeshksootar@gmail.com Keywords: Wheat, selection indices, physiological traits, drought. Abstract. The current study was planned to identify drought tolerance bread wheat genotypes based on physiological and yield traits. In this context, a set of 12 genotypes (Sarsabz, NIA-Sundar, NIA- Amber, Sassui, Khirman, Marvi-2000, NIA-Sarang, Kiran-95, NIA-Sunheri, Bhittai, Bathoor-08 and Tatara) were evaluated under optimum and water stress conditions. Mean squares from analysis of variance exhibited that genotypes, treatments and genotype x treatment interaction showed significant differences (P<0.05) for majority of the studied traits, indicating that there is significant variations are existing for physio-yield traits; therefore these genotypes may be preferred for further breeding programs with respect to drought stress. Regarding reduction percentage of genotypes under drought stress against optimum water conditions, the minimum reduction was observed in Bathoor-08 for spike length and flag leaf area, Kiran-95 for grain yield plant, NIA-Sundar for seed index, Marvi-2000 for relative water content, Sarsabz for grains spike, whereas maximum but desirable reduction of stomatal dimension and density was displayed by Sarsabz and Tatara under water stress conditions, respectively. On the basis of drought tolerant indices, the genotypes Kiran- 95, NIA-Sundar and Sarsabz showed lower values for tolerance index (TOL), trait stability index (TSI) and stress susceptibility (SSI), nevertheless, it is believed that lower values of these indices show the less reduction in yield and its related traits due to water stress conditions hence can be tagged as tolerant genotypes for drought. Correlation results revealed that MP, SSI, TOL and TSI indices were correlated with grain yield under two conditions and they can be the appropriate indices for screening wheat genotypes. Introduction Wheat is the world most important cereal crop in terms of area and production. It has been grown in a wide range of arid and semi-arid regions, where due to rainfall fluctuations in rain-fed regions, drought occurs frequently [1]. Nowadays, in most countries wheat is the major staple food for people, because it provides more than 20% of the needed energy of the population in the world [2]. From all the stresses either biotic or abiotic factors, it is drought which plays a significant role in the reduction of wheat production and performance upto a great extent. It is recognized that almost 50% of wheat cultivated land in the developing countries is under rainfed condition [3]. Drought has been a worldwide problem constraining global crop production seriously [4]. Drought, being the important environmental stress, severely impairs plant growth and development [5]. The severe effects of drought are numerous, including: reduction in the crop yield, unavailability of fodder and feed. Wheat yield is reduced by 57% from their potential because of drought spell on about 60 million hectare in the developing world [6]. Water stress at all stages of plant growth affects the grain yield but when it takes place in critical stages of growth, grain yield is sharply Journal of Horticulture and Plant Research Submitted: 2019-04-03 ISSN: 2624-814X, Vol. 7, pp 40-52 Revised: 2019-05-08 doi:10.18052/www.scipress.com/JHPR.7.40 Accepted: 2019-08-07 2019 SciPress Ltd, Switzerland Online: 2019-08-28 SciPress applies the CC-BY 4.0 license to works we publish: https://creativecommons.org/licenses/by/4.0/