University of Guilan Cereal Research 2252-0163 2 3 2012 12 27 Effect of drought stress on yield and yield components in rice landraces and improved cultivars under Gonbad Kavous environmental condition Effect of drought stress on yield and yield components in rice landraces and improved cultivars under Gonbad Kavous environmental condition 165 179 1654 FA Mahdi Ghiasy Former Graduate Student, Dept. of Plant Breeding, University of Shahid Bahonar Kerman Hassan Farahbakhsh Assist. Prof., Dept. of Plant Breeding, University of Shahid Bahonar Kerman Hossein Sabouri Assist. Prof., Dept. of Plant Production, College of Agriculture and Natural Resources, Gonbad Kavous University Ghasem Mohammadinejad Assist. Profs., Dept. of Plant Breeding, University of Shahid Bahonar Kerman Journal Article 2012 09 09 To evaluate seed yield and some associated characteristics in rice under drought stress conditions, 15 rice genotypes (including seven local and eight foreign varieties) were studied in two environments (normal and drought stress conditions) using randomized complete block design with three replications in research field of Faculty of Agricultural Sciences, Gonbad Kavous University, in 2008. Analysis of variance showed that there were significant effect (p<0.01) of genotypes on all traits in two environments, so that local varieties showed a better response to drought stress than foreign varieties. Mean comparison of genotypes showed that the highest yield belonged to Domsiah and Sorkho cultivars in normal condition and Gardeh in stress condition. Evaluating the reduction percentage of traits mean showed that most damage of drought stress was due to increasing of unfilled grains (23.45%). 100 kernel weight  under normal condition (0.89) and the number of filled grains under drought stress condition (0.92) had the highest positive correlation with the grain yield. Results of path analysis showed that the highest positive direct effect on grain yield was related to 100 kernel weight and the number of filled grains in non-stress and stress conditions, respectively, which were considered as the most important agronomic traits for selecting the higher yield cultivars under flooded and drought stresses. To evaluate seed yield and some associated characteristics in rice under drought stress conditions, 15 rice genotypes (including seven local and eight foreign varieties) were studied in two environments (normal and drought stress conditions) using randomized complete block design with three replications in research field of Faculty of Agricultural Sciences, Gonbad Kavous University, in 2008. Analysis of variance showed that there were significant effect (p<0.01) of genotypes on all traits in two environments, so that local varieties showed a better response to drought stress than foreign varieties. Mean comparison of genotypes showed that the highest yield belonged to Domsiah and Sorkho cultivars in normal condition and Gardeh in stress condition. Evaluating the reduction percentage of traits mean showed that most damage of drought stress was due to increasing of unfilled grains (23.45%). 100 kernel weight  under normal condition (0.89) and the number of filled grains under drought stress condition (0.92) had the highest positive correlation with the grain yield. Results of path analysis showed that the highest positive direct effect on grain yield was related to 100 kernel weight and the number of filled grains in non-stress and stress conditions, respectively, which were considered as the most important agronomic traits for selecting the higher yield cultivars under flooded and drought stresses. https://cr.guilan.ac.ir/article_1654_f40966afd431786bd0e0f6406afaad3a.pdf