Relative contributions of light interception and radiation use efficiency to the reduction of maize productivity under cold temperatures

Maize (Zea mays L.) is a chill-susceptible crop cultivated in northern latitude environments. The detrimental effects of cold on growth and photosynthetic activity have long been established. However, a general overview of how important these processes are with respect to the reduction of productivity reported in the field is still lacking. In this study, a model-assisted approach was used to dissect variations in productivity under suboptimal temperatures and quantify the relative contributions of light interception (PARc) and radiation use efficiency (RUE) from emergence to flowering. A combination of architectural and light transfer models was used to calculate light interception in three field experiments with two cold-tolerant lines and at two sowing dates. Model assessment confirmed that the approach was suitable to infer light interception. Biomass production was strongly affected by early sowings. RUE was identified as the main cause of biomass reduction during cold events. Furthermore, PARc explained most of the variability observed at flowering, its relative contributions being more or less important according to the climate experienced. Cold temperatures resulted in lower PARc, mainly because final leaf length and width were significantly reduced for all leaves emerging after the first cold occurrence. These results confirm that virtual plants can be useful as fine phenotyping tools. A scheme of action of cold on leaf expansion, light interception and radiation use efficiency is discussed with a view towards helping breeders define relevant selection criteria. This paper originates from a presentation at the 5th International Workshop on Functional–Structural Plant Models, Napier, New Zealand, November 2007.

School and choice : Anethnography of a primary school with bilingual classes

Based on a one-year ethnographic study of a primary school in Finland with specialised classes in Finnish and English (referred to as bilingual classes by research participants), this research traces patterns of how nationed, raced, classed and gendered differences are produced and gain meaning in school. I examine several aspects of these differences: the ways the teachers and parents make sense of school and of school choice; the repertoires of self put forward by teachers, parents and pupils of the bilingual classes; and the insitutional and classroom practices in Sunny Lane School (pseudonym). My purpose is to examine how the construction of differentness is related to the policy of school choice. I approach this questions from a knowledge problematic, and explore connections and disjunctions between the interpretations of teachers and those of parents, as well as between what teachers and parents expressed or said and the practices they engaged in. My data consists of fieldnotes generated through a one-year period of ethnographic study in Sunny Lane School, and of ethnographic interviews with teachers and parents primarily of the bilingual classes. This data focuses on the initial stages of the bilingual classes, which included the application and testing processes for these classes, and on Grades 1─3. In my analysis, I pursue poststructural feminist theorisations on questions of knowledge, power and subjectivity, which foreground an understanding of the constitutive force of discourse and the performative, partial, and relational nature of knowledge. I begin by situating my ethnographic field in relation to wider developments, namely, the emergence of school choice and the rhetoric of curricular reform and language education in Finland. I move on from there to ask how teachers discuss the introduction of these specialised classes, then trace pupils paths to these classes, their parents goals related to school choice, teachers constructions of the pupils and parents of bilingual classes, and how these shape the ways in which school and classroom practices unfold. School choice, I argue, functioned as a spatial practice, defining who belongs in school and demarcating the position of teachers, parents and pupils in school. Notions of classed and ethnicised differences entered the ways teachers and parents made sense of school choice. Teachers idealised school in terms of social cohesiveness and constructed social cohesion as a task for school to perform. The hopes parents iterated were connected to ensuring their children s futurity, to their perceptions of the advantages of fluency in English, but also to the differences they believed to exist between the social milieus of different schools. Ideals such as openmindedness and cosmopolitanism were also articulated by parents, and these ideals assumed different content for ethnic majority and minority parents. Teachers discussed the introduction of bilingual classes as being a means to ensure the school s future, and emphasised bilingual classes as fitting into the rubric of Finnish comprehensive schooling which, they maintained, is committed to equality. Parents were expected to accommodate their views and adopt the position of the responsible, supportive parent that was suggested to them by teachers. Teachers assumed a posture teachers of appreciating different cultures, while maintaining Finnishness as common ground in school. Discussion on pupils knowledge and experience of other countries took place often in bilingual classes, and various cultural theme events were organized on occasion. In school, pupils are taught to identify themselves in terms of cultural belonging. The rhetoric promoted by teachers was one of inclusiveness, which was also applied to describe the task of qualifying pupils for bilingual classes, qualifying which pupils can belong. Bilingual classes were idealised as taking a neutral, impartial posture toward difference by ethnic majority teachers and parents, and the relationship of school choice to classed advantage, for example, was something teachers, as well as parents, preferred not to discuss. Pupils were addressed by teachers during lessons in ways that assumed self responsibility and diligence, and they assumed the discursive category of being good, competent pupils made available to them. While this allowed them to position themselves favourably in school, their participation in a bilingual class was marked by the pressure to succeed well in school.