Genetic Progress From 50 Years of Smooth Bromegrass Breeding

Since its introduction from Eurasia, smooth bromegrass (Bromus inermis Leyss.) has become an important cool-season forage grass in North America. The objective of this study was to document breeding progress in smooth bromegrass between 1942 and 1995 in North America. Thirty cultivars or experimental populations were tested at up to seven sites in the eastern and central USA, with a range of soil types and climates. There have been small genetic changes in forage yield, brown leafspot resistance [caused by Pyrenophora bromi (Died) Drechs.], in vitro dry matter digestibility (IVDMD), and neutral detergent fiber (NDF) concentration. Brown leafspot resistance increased gradually, averaging 0.21 units decade(-1). Mean forage yield did not change for cultivars developed after 1942, but was 0.54 Mg ha(-1) (7.2%) higher for the post-1942 group than in \u27Lincoln\u27, a direct representative of smooth bromegrass introduced into North America. Selection for increased IVDMD led to an average increase in IVDMD of 9 g kg(-1) (1.4%), an increase in forage yield of 0.33 Mg ha(-1) (5.0%), and a decrease in NDF of -8 g kg(-1) (-1.2%) in the post-1942 group. The slow rate of progress for smooth bromegrass forage yield is due to its complex polypoid inheritance, emphasis on traits other than forage yield, and relatively little concentrated attention from public and private breeders

Latitudinal and Longitudinal Adaptation of Smooth Bromegrass Populations

Breeding progress has been slow in smooth bromegrass (Bromus inermis Leyss) since its introduction to North America. Much of the variability among cultivars appears to have arisen by natural selection and adaptive responses. The objective of this study was to determine if smooth bromegrass cultivars differ in latitudinal or longitudinal adaptation, as measured by forage yield, and if that variability relates to their breeding or selection history. The target region was defined as the Great Plains to the East Coast of the USA, from 38 to 47 degrees N latitude. Twenty-nine cultivars and experimental populations were evaluated for forage yield at up to seven locations ranging from central to eastern USA. Populations were classified according to pooled population main effect and population x location interaction effect (G + GL deviations). Cluster analysis resulted in eight clusters that explained 90% of the variation among G + GL deviations. One cluster consisted of populations average in adaptation, four clusters consisted of populations that were largely unadapted across the entire region, and three clusters consisted of populations that were specifically adapted to the entire region or a large part thereof. Much of the grouping and adaptation characteristics could be explained by similar pedigrees, selection history, and selection location. However, the phenotypic similarity of some superior, but divergent-pedigree populations suggested that alleles for high and stable forage yield in smooth bromegrass probably exist in numerous germplasm sources. Despite a history of little to no gains in forage yield, these results suggest unrealized potential for future improvement of forage yield of smooth bromegrass across a broad geographic region

Rational land and housing bubbles in infinite-horizon economies

URL des Documents de travail : http://ces.univ-paris1.fr/cesdp/cesdp2016.htmlDocuments de travail du Centre d'Economie de la Sorbonne 2016.27 - ISSN : 1955-611XThis paper considers rational land and housing bubbles in an infinite-horizon general equilibrium model. Their demands rest on two different grounds: the land is an input to produce while the house may be consumed. Our work differs from the existing literature in two respects. First, dividends on both these long-lived assets are endogenous and their sequences are computed. Second, we introduce and study different concepts of bubbles, including individual and strong bubbles

Pleasure in decision-making situations

BACKGROUND: This study explores the role of pleasure in decision making. RESULTS: In Experiment 1, 12 subjects were presented with a questionnaire containing 46 items taken from the literature. Twenty-three items described a situation where a decision should be made and ended with a suggested solution. The other items served as filler items. The subjects were requested not to make a decision but to rate the pleasure or displeasure they experienced when reading the situation described in the item. The subjects' ratings were then compared to the decisions on the same situations made by the other subjects of the studies published by other workers. The ratings of pleasure/displeasure given by our subjects correlated significantly with the choices published by other authors. This result satisfies a necessary condition for pleasure to be the key of the decision making process in theoretical situations. In Experiment 2, a new group of 12 subjects rated their experience of pleasure/displeasure when reading various versions of 50 situations taken from daily life where an ethical decision had to be made (Questionnaire I) including 200 items. This was followed by a multiple-choice test with the 50 situations (Questionnaire II) using the same 200 items and offering the various behaviors. Subjects tended to choose ethical and unethical responses corresponding to their highest pleasure rating within each problem. In all cases the subjects' behavior was higher than chance level, and thus, followed the trend to maximize pleasure. In Experiment 3, 12 subjects reading 50 mathematical short problems followed by correct and incorrect versions of the answer to the problem (Questionnaire III), including 200 items. This was followed by a multiple-choice mathematical test with the 50 problems (Questionnaire IV) using the same 200 items and offering the correct and incorrect answers. In questionnaire IV, subjects tended to choose correct as well as incorrect responses corresponding to their highest hedonic rating within each problem. In all cases the subjects' behavior was higher than chance level, and thus, followed the trend to maximize pleasure. CONCLUSIONS: The results of the three experiments support the hypothesis according to which decisions are made in the hedonic dimension of conscious experience