Effect of Elymus repens on yield of winter wheat, spring barley and faba bean in an organic crop rotation experiment

The impact of crop rotation, nutrient levels and use of catch crops on effect of E. repens on a sandy soil at Jyndevad on yield of winter wheat (2006), spring barley (2007-2008) and faba bean (2006-2008) was studied in an existing organic crop rotation experiment (Olesen et al., 2000; Rasmussen et al., 2006). Some of the objectives were to determine the yield loss at different levels of infestation of the weed, and to determine whether this relationship was influenced by the treatments. For all crops, the treatments had a high impact on the yield. The two treatments that had no manure applied for up to 12 years consistently had the lowest yields. In spring barley, the two treatments with manure and with catch crops consistently had the highest yields. In faba bean, the treatment with manure and without catch crops had the highest yields. As for the effect of E. repens shoots on yield, in spring barley, there was a larger decrease in the system without grass clover. The same tendency was seen for winter wheat. For spring barley and faba bean, within each system (with or without grass clover), the yield in treatments without manure was less influenced by E. repens than in treatments with manure

Samfundsfagdidaktiske problemstillinger set fra lærernes perspektiv:

Samfundsfagdidaktiske problemstillinger set fra lærernes perspektiv

Vidensformer i samfundsfag

Vidensformer i samfundsfa

Trends in high life satisfaction among adolescents in five Nordic countries 2002–2014

Life satisfaction is an important indicator when assessing positive mental health aspects in populations, including among adolescents. The aim of this study was to investigate trends over time in prevalence of high life satisfaction among adolescents from five Nordic countries: Denmark, Iceland, Finland, Norway and Sweden. We used data from four waves of the Health Behaviour in School-Aged Children study from 2002, 2006, 2010 and 2014 (n=109,847). HBSC is a school-based study examining social circumstances, health and health behaviour among 11-, 13- and 15-years olds every four years in many European and North American countries. The Cantril Ladder, an 11-step visual analogue scale, was used as the measure of life satisfaction, and was dichotomised into two groups: high life satisfaction (scoring 9 or 10 on the scale) and medium/low life satisfaction (scoring <9). Over the 12-year period studied, between 28.6 and 44.8% of adolescents in the five countries rated their life satisfaction as high. Relatively large changes in prevalence levels occurred at the country level over the period. Denmark and Finland showed a steady, significant decline in the prevalence of high life satisfaction over the years. Iceland showed the highest prevalence in 2010. Norway and Sweden showed similar development until 2010, followed by a clear increase for Norway and a sharp decline in adolescent high life satisfaction for Sweden up until 2014. In all countries, high life satisfaction was most prevalent in 11-year- olds and least prevalent in almost all surveys among 15-year-old girls.peerReviewe

<i>Cupriavidus pinatubonensis</i> AEO106 deals with copper-induced oxidative stress before engaging in biodegradation of the herbicide 4-chloro-2-methylphenoxyacetic acid

Abstract Background Microbial degradation of phenoxy acid (PA) herbicides in agricultural soils is important to minimize herbicide leaching to groundwater reservoirs. Degradation may, however, be hampered by exposure of the degrader bacteria to toxic metals as copper (Cu) in the soil environment. Exposure to Cu leads to accumulation of intracellular reactive oxygen species (ROS) in some bacteria, but it is not known how Cu-derived ROS and an ensuing oxidative stress affect the degradation of PA herbicides. Based on the previously proposed paradigm that bacteria deal with environmental stress before they engage in biodegradation, we studied how the degradation of the PA herbicide 2-methyl-4-chlorophenoxyacetic acid (MCPA) by the model PA degrader Cupriavidus pinatubonensis AEO106 was affected by Cu exposure. Results Exposure of C. pinatubonensis in batch culture to sublethal concentrations of Cu increased accumulation of ROS measured by the oxidant sensing probe 2,7-dichlorodihydrofluorescein diacetate and flow cytometry, and resulted in upregulation of a gene encoding a protein belong to the Ohr/OsmC protein family. The ohr/osmC gene was also highly induced by H2O2 exposure suggesting that it is involved in the oxidative stress response in C. pinatubonensis. The increased ROS accumulation and increased expression of the oxidative stress defense coincided with a delay in the catabolic performance, since both expression of the catabolic tfdA gene and MCPA mineralization were delayed compared to unexposed control cells. Conclusions The current study suggests that Cu-induced ROS accumulation in C. pinatubonensis activates a stress response involving the product of the ohr/osmC gene. Further, the stress response is launched before induction of the catabolic tfdA gene and mineralization occurs