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For evaluation of genetic diversity among improved alfalfa varieties and Iranian landraces, 12 populations including five improved varieties (Kaysari, Kadi, Ranger, Mesmir, Seariver) and seven landraces (Gharayonje, Amozeynadin, Rahnani, Tazekand, Shazand, Hamedani, Yazdi) were evaluated using agronomic traits and enzyme markers. Thirty-five individuals of each variety were grown and analyzed in separate pots in a unbalanced completely randomized design (CRD). Analysis of variance for agronomic traits showed significant differences for most of the traits among improved and landrace varieties. For esterase and peroxidase enzymes based on presence or absence of enzyme bands (1, 0) eleven polymprphic isozyme bands were detected. For improved and landrace varieties Shanon index mean was 0.48 ± 0.246 and 0.519 ± 0.193, respectively, furthermore Nei genetic diversity index mean for improved and landraces was 0.327 ± 0.181 and 0.352 ± 0.148 respectively, suggesting no difference between improved and landrace varieties was found. Analysis of relation between isozyme markers and agronomic traits showed that there are significant differences between the presence of POX-4 and wet and dry yield in improved varieties.

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Drought stress is one of the factors that reduces yield in the world. Considering that wheat is grown mostly in semi-arid areas, much attention has been paid to develop drought tolerant varieties. This experiment was conducted during 2013-2014 in Tabriz University research farm, Iran. In this investigation the inheritance of some agronomic and physiological traits was studied in the field condition through generations mean analysis. The generations were produced from the cross of Arg (tolerant to drought) and Moghan3 (sensitive to drought) varieties. The experiment was a split plot design based on randomized complete blocks with two replications. The irrigation conditions were arranged in the main plots and generations in the subplots. In the stress condition, irrigation was withheld after pollination. Based on the analysis of variance, significant difference were observed among different generations in terms of plant height, peduncle length, flag leaf length, flag leaf width, number of fertile tillers, leaf chlorophyll content, leaf temperature, days to maturity, spike weight, straw weight, biomass, grain yield and harvest index. The interaction between generations and irrigation conditions was significant only for grain yield. The generation mean analysis in both normal and drought stress conditions showed that chi-square of three parameter model was significant for all of the studied characteristics, indicating the presence of non-allelic interactions in the inheritance of these traits. The broad sense and narrow sense heritabilities for the traits under study were estimated as 0.502-0.946 and 0.244-0.429 in the normal condition and 0.653-0.951 and 0.221-0.377 in the water stress condition, respectively. The average degree of dominance for all of the characters in both normal and water stress conditions was greater than one which indicated the existence of over-dominance gene action in controlling these traits. At both conditions, the dominance genetic variance was higher than the additive genetic variance for all of the traits. The results indicate the necessity of selection in advanced generation or exploiting dominance gene action in the breeding programs, if hybrid varieties are produced in the wheat plant.