Breadth of Participation in Organized and Unstructured Leisure Activities Over Time and Rural Adolescents’ Functioning

Discretionary time outside of school offers a distinct context that can promote adolescent development; however, potential for growth depends in part on how this time is used. In this study, person-centered analyses were used to examine patterns of breadth of participation in both organized and unstructured leisure activities among rural adolescents (N = 276, 49 % female) across grades 7, 8, and 10. Adjusting for self-selection factors, the study associated these patterns with 10th grade outcomes. Three profiles of participation emerged: consistently low breadth, consistently average breadth, and consistently high breadth of involvement in both organized and unstructured leisure activities over time. The most popular activity types across profile groups were hanging out with friends, team sports, and outdoor activities. Adolescents involved in a greater breadth of organized activities reported the greatest breadth of involvement in unstructured leisure and the best functioning. Adolescents with low breadth of involvement in both organized and unstructured leisure activities consistently showed poorer outcomes. Adolescents in the high breadth of involvement profile were engaged in all activity types at higher rates than adolescents in the average and low breadth of involvement profiles. We advocate for continued efforts to increase adolescent participation in a variety of different types of out-of-school activities

Photosynthesis in poor nutrient soils, in compacted soils, and under drought

Plants require the uptake of nutrients (in most cases via roots) and their incorporation into plant organs for growth. In non-woody species, 83% of fresh weight is water, 7% is carbon, 5% is oxygen, with the remaining 5% including hydrogen and such nutrients. In natural ecosystems, availability of nutrients in soils is heterogeneous, and many species often adapt their growth to the amount of nutrients that roots can take up by exploring the available soil volume. In agricultural areas, the lack of some nutrients is frequent. In both cases, plants must also face periods of drought and soil compaction. These environmental stresses are therefore not uncommon in natural ecosystems and crops, and the stressed plants often experience a decrease in photosynthetic CO2 fixation. In this chapter, we review changes observed in photosynthesis in response to nutrient deficiencies, soil compaction, and drought. The current knowledge on photosynthesis in carnivorous plants, as a special case of plant species growing in nutrient poor soils, is also included. Pigment limitations (chlorosis and/or necrosis), stomatal limitations, ultrastructural effects and mesophyll conductance limitations, photochemistry (primary reactions), carboxylation and Calvin-cycle reactions, and carbohydrate metabolism and transport will be discussed. With regard to nutrients, we have focused on the most common nutrition-related stresses in plants, the deficiencies of macro- (nitrogen, phosphorous, and potassium) and micronutrients (iron, manganese, copper, and zinc). Other nutrient deficiencies (or toxicities, both in the cases of essential nutrient excess or heavy metals) are not reviewed here. For other nutrient deficiencies and toxicities, and the role of the above-mentioned, and other nutrients (such as calcium and magnesium) in gas exchange, and as intracellular signal transducers, enzyme activators, and structure and function stabilizers of biological membranes, readers are referred to papers published elsewhere (Marschner H, Mineral nutrition of higher plants. Academic, London, 1995; Cakmak I, Kirkby EA, Physiol Plant 133:692–704, 2008; Morales F, Warren CR, Photosynthetic responses to nutrient deprivation and toxicities. In: Flexas J, Loreto F, Medrano H (eds) Terrestrial photosynthesis in a changing environment: a molecular, physiological and ecological approach. Cambridge University Press, Cambridge, pp 312–330, 2012; Hochmal AK, Schulze S, Trompelt K, Hippler M, Biochim Biophys Acta 1847:993–1003, 2015).This study was supported by the Spanish Ministry of Economy and Competitiveness (MINECO; projects AGL2012-31988, AGL2013-42175-R, AGL2016-75226-R, and AGL2016-79868-R, co-financed with FEDER), the Aragón Government (Group A03), grant LO1204 (Sustainable development of research in the Centre of the Region Haná) from the National Program of Sustainability I, and by the Czech Science Foundation Agency (project 16-07366Y). FM wishes to thank JC Martínez for his help with some periodic bibliographic searches.Peer reviewe