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Designing breeding programs for winter rapeseed (Brassica napus L.) cultivars with improved seed and oil yields requires information about the genetic variability of traits. In this study, 28 winter rapeseed cultivars were evaluated for genetic variation and relationships between 11 agro-morphological characters during 2010 and 2011. Cultivars and cultivar × year interaction showed significant variation for all studied traits. Genotypic coefficients of variation indicated that yield, number of branches per plant, and plant height had the highest variation. Broad sense heritability estimates ranged from 6% to 87% for seed yield and pod length, respectively. Positive correlation was found between seed yield with number of pods per plant, number of branches per plant, days to flowering, and days to ripening. The result of factor analysis showed three independent factors that explained 71% of the total variability, which were named ‘productivity’, ‘phenology and oil’, and ‘pod length’, respectively. According to the first factor, RGS003, Opera, and Hayola were identified as high seed yielding cultivars. Based on all three factors, Lilian, Licord, and Ella were identified as the best cultivars concerning seed yield and oil content. 

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Tall fescue is an out-crossing allohexaploid grass species extensively used for forage and turf worldwide. Cultivars of outbreeding forage grasses such as tall fescue are usually synthetic populations derived from intercrossing several selected parents using the polycross method. In this study, the application of AFLP molecular markers to optimize genetic diversity in a polycross breeding program of tall fescue was evaluated. For both phenotypic characters and AFLP molecular markers, two polycrosses of six parental plants with contrasting levels of genetic diversity were composed. A fifth polycross population was composed using six genotypes with the highest general combining ability. The results of this study showed that marker assistant parental selection produced superior progenies, indicating that selection based on molecular marker diversity may be an appropriate means to improve first generation progenies of tall fescue. This may be mainly useful in large breeding programs because the identification of diversity based on phenotypic traits is time consuming and may be influenced by environmental effects.

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To develop synthetic varieties, not only the estimation of General Combining Ability (GCA) for forage production is required but also the stability of GCA for parental genotypes is necessary. Little is known about genetic analysis and selection for high production, combining ability, and stability in grasses. In this study, half-sib families derived from the polycross of 25 smooth bromegrass genotypes were evaluated under 10 environments (combination of five years and two moisture environments, including non-stressed and drought stress conditions). Considerable variation for genetic and Genotype×Environment (G×E) interaction was found among half-sib families. Low broad sense heritability (27%) was found for forage yield indicating that selection based on an index may be more useful for improvement of this trait in recurrent selection programs. On the other hand, since the interactions of genetic by environment are significant, selection of superior genotypes for development of synthetic varieties should be done based on multi-environments trails.

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There are contrasting reports on the relationship between production and drought tolerance of crops with root structure. The presented research aimed to evaluate grain yield and root-related traits (in two depths) under optimal and drought stress conditions and assess the effect of root-related traits on grain yield and drought tolerance in cultivated barley (Hordeum vulgare ssp. vulgare) and wild barley (H. vulgare ssp. spontaneum). In this experiment, 30 barley genotypes were evaluated in pot culture experiment for root traits and in the field for grain yield and drought tolerance for two consecutive years. The results indicated that the genotypes with high root dry weight, area, volume and length and root to shoot ratio in depth 0-30 cm have also high value of these root traits under the depth of 30-60 cm. In this study, the root system size increased when the plants imposed to drought stress, and the level of increase was higher in the deeper soil layer. The wild barley genotypes Hsp06, Hsp74 and Hsp79 had high averages of the root dry weight, area, volume and length under both water environments. The results of farm experiment indicated that the genotypes from cultivated barley mostly have higher yield potential; however, the wild barley genotypes mainly have more yield stability under drought stress environment. The wild barley Hsp71 was identified with both high yield potential and stability under drought stress. Root dry weight and root to shoot ratio were negatively correlated with grain yield under control conditions. Under stress condition, root area, length and volume were positively correlated with yield stability index. Results indicated that the vigorous root system is not necessarily related to higher grain yield in barley; however, higher yield stability under stress environment is highly related.