Exploring reading in social semiotics: theory and methods

The aim of this paper is to critically review how social semiotics has contributed to the study of reading and to develop an agenda for further research. We consider the theoretical and methodological resources that social semiotics has developed to account for multimodal text in the contemporary semiotic landscape, and explore how they can be used to teach critical reading skills to young people to support their participation in different social domains. We reflect on the possibilities and limitations of different analytical frameworks, highlighting barriers and possibilities for advancing social semiotic scholarship on reading and beyond. We end with a sketch of a new research agenda for social semiotics, in the light of technological change and its implications for reading

Exogenous application of plant defense hormones alters the effects of live soils on plant performance

Plant science

The negative effects of soil microorganisms on plant growth only extend to the first weeks

AimsSoil biotic communities can strongly impact plant performance. So far, most studies on plant-soil-interactions have estimated the effect of the soil microbial community on plant mass after a fixed duration of plant growth. However, these interactions may change over time and several studies have argued that plant-soil interactions are more important for young seedlings than for older plants. In this paper we ask the question: how long-lasting the effect of the soil microbial community on plant growth is. This is important as the growth rate of a plant is not only determined by the growing conditions but also by the size of the plant itself. Therefore, plant with a reduced growth rate early in life, due to negative effects of the soil microbial community, may increase less in biomass for a much longer period even though the relative growth rates do not differ any longer.MethodsWe examined the plant growth rates at three stages: early growth (0-21 days), mid growth (22 to 42 days) and late growth (43 to 63 days). We performed two growth experiments with Jacobaea vulgaris lasting 49 and 63 days. Plants were grown in sterilized soil or in sterilized soil inoculated with natural dune soil. In a third experiment, we examined the effect of the timing of soil inoculation prior to planting on the (relative-) growth rate of J. vulgaris plants with four different timing treatments.Important findingsIn all experiments, differences in biomass of plants grown in sterilized soil and inoculated soil (live soil) increased throughout the experiment. Interestingly, linear regression models with ln transformed dry weight against time for younger plants and for older plants in sterilized soil and live soil, respectively, showed that the relative growth rate of plants in the sterilized soil was only significantly higher than that of plants in the live soil in the first two to three weeks. After that period there was no longer a negative effect of the live soil on the relative growth rate of plants. In the third experiment, plant biomass decreased with increasing time between inoculation and planting. Overall, our results show that plants of J. vulgaris grew less well in live soil than in sterilized soil. The negative effects of soil inoculation on plant mass appeared to extend over the whole growth period but arise from the negative effects on relative growth rates that occurred in the first weeks after planting when plants have only less than 5% of the mass they obtained after 42 days. Our study highlights the importance of examining relative growth rates rather than final biomass to estimate the effects of soil microbial communities on plants.Plant science

Belowground responses of bacterial communities to foliar SA application over four plant generations

Background and aims Jacobaea vulgaris plants grow better in sterilized than in live soil. Foliar application of SA mitigates this negative effect of live soil on plant growth. To examine what causes the positive effect of SA application on plant growth in live soils, we analyzed the effects of SA application on the composition of active rhizosphere bacteria in the soil. Methods We studied the composition of the microbial community over four consecutive plant cycles (generations), using mRNA sequencing of the microbial communities in the rhizosphere of J. vulgaris. We initiated the experiment with an inoculum of live soil collected from the field, and at the start of each subsequent plant cycle, we inoculated a small part of the soil from the previous plant cycle into sterile bulk soil. Results Application of SA did not significantly increase or decrease the Shannon diversity at genus level within each generation, but several specific genera were enriched or depleted after foliar SA application. The composition of bacterial communities in the rhizosphere significantly differed between plant cycles (generations), but application of SA did not alter this pattern. In the first generation no genera were significantly affected by the SA treatment, but in the second, third and fourth generations, specific genera were significantly affected. 89 species out of the total 270 (32.4%) were present as the "core" microbiome in all treatments over four plant cycles. Conclusions Overall, our study shows that the composition of bacterial genera in the rhizosphere significantly differed between plant cycles, but that it was not strongly affected by foliar application of SA on J. vulgaris leaves. Further studies should examine how activation of the SA signaling pathway in the plant changes the functional genes of the rhizosphere bacterial community.Plant science

Creativity under task conflict: The role of proactively increasing job resources

The present daily diary study among employees from various occupational sectors used conflict and creativity theories to hypothesize that task conflict has an inverted U-shaped relationship with employee creativity (i.e., creativity is higher at moderate than low or high levels of conflict). In addition, we argue that this curvilinear effect is likely to occur when employees proactively increase their job resources. A total of 92 employees filled out a diary survey at the end of five consecutive days. Results of multilevel analyses revealed that, as predicted, task conflict had an inverted U-shaped link with creativity when employees increased their structural job resources. However, when employees increased their social job resources, the link was linear and positive. Our findings also showed that increasing job resources related positively to employee creativity – this effect was found for both increasing structural and social job resources. We discuss the theoretical contributions of these findings and conclude that moderate task conflict has the potential to benefit organizations

Associational resistance to nematodes and its effects on interspecific interactions among grassland plants

AimsPlants can influence the level of herbivory experienced by neighboring plants. The importance of such belowground associational effects are poorly understood. In this study we examine whether Jacobaea vulgaris provides associational resistance against nematodes to neighboring plants.MethodsThirteen species (6 forbs, 3 grasses and 4 legumes) were each grown in mixtures with J. vulgaris and in monocultures. A nematode community was introduced to half of the pots. After 12 weeks, plant dry mass was assessed for each individual plant in each pot, and the number of nematodes in the soil and roots were identified. We then examined for each plant species its performance in mixtures and in monocultures, in presence and absence of nematodes and analyzed the abundance and composition of nematodes.ResultsForbs produced more, grasses similar, and legumes less biomass in mixtures with J. vulgaris than in monocultures. Nematode addition did not influence biomass. There were fewer root-feeding nematodes in the soil in mixtures than in monocultures, but this was only true for plants that were good hosts for nematodes. The community composition of soil nematodes was different in monocultures and mixtures. Densities of migratory endoparasitic nematodes in the roots of neighboring plants were lower in mixtures than in monocultures. Moreover, the presence of nematodes changed the outcome of plant-plant interactions, often in favor of J. vulgaris.ConclusionsJacobaea vulgaris provides belowground associational resistance to other plants against migratory endoparasitic nematodes, and the presence of nematodes can change the outcome of plant-plant interactions.Plant science