To study the genetic variation, heritability and genetic correlations of some agro-morphological traits in tall fescue, 25 parents from a genetically broadbase germplasm were polycrossed and their respective half-sib families were generated. Clonally propagated parents and their half-sib families were grown as spaced single plants using a randomized completeblock design with three replications, and observed for seven traits in 2006 and 2007. The estimates of broad-sense heritability h 2 n À Á were moderate to high h 2 b ¼ 0:43 À 0:80 À Á for the traits studied. Narrowsense heritability h 2 n À Á estimates from analyses of progenies and from regression of half-sib (HS) progenies on parents h 2 op suggested that genetic variation for these traits was largely controlled by additive gene action. Association of dry matter yield (DMY) with plant height, number of fertile shoot, curbs width and spring growth was positive and significant. With the exception of number of days to pollination, correlation coefficients of the traits between the parents and offspring were not significant. Based on parentoffspring regression, genetic gain from selection for DMY was high, demonstrating genetic potential for improving this trait. Overall, there was high genetic variation and moderate heritability for most traits in the tall fescue populations evaluated. In conclusion, to improve herbage yield, selection would be more effective based on forage yield components.
This research was conducted to study the genetic diversity in safflower (Carthamus tinctorius L.) using agro-morphological traits and RAPD markers. Sixteen selected lines derived from landraces growing in various agro-climatic regions of Iran along with four exotic genotypes were evaluated in a randomized complete block design with three replications under field conditions. Days to emergence, days to initial flowering, days to flowering, days to maturity, plant height, branches per plant, capitula per plant, seeds per capitulum, 1,000-seed weight, seed yield per plant, seed yield, and reaction to powdery mildew (Leveillula taurica Arnaud) were evaluated in this study.
Tall fescue (Festuca arundinacea Schreb.) is an outcrossing allohexaploid grass species extensively used for forage and turf worldwide. Twenty‐five genotypes of tall fescue were chosen from a broad‐base population and the genetic diversity was evaluated based on expressed sequence tag‐simple sequence repeat molecular markers and agronomical and morphological traits. Their respective half‐sib polycross progenies were also evaluated for these same traits at six environments (two locations for 3 yr). The high genotypic variation observed for plant seed yield and some morphological traits in parental genotypes and their respective progenies indicated high potential for improving these traits through targeted selection in breeding programs. Family and family × location interactions were significant for most characteristics. Narrow‐sense heritability estimates were moderately high for plant seed weight (49%), number of fertile tillers (46%), panicle length (45%), and plant height (44%). These indicate that family selection methods should be more effective than individual selection. Stable families across environments were identified based on the regression coefficients, deviations from the regression, and yield potential indicating the usefulness of these parameters in the selection process for seed and forage yield improvement where additive × environment interactions are present.
Many dentists experience the MSDs, especially in cervical region, as a consequence of occupational stresses. Therefore, detecting occupational risk factors, standards of work position, regular exercise and following ergonomic policy are intensely recommended.
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