Language Beyond the Classroom: A Guide to Community-Based Learning for World Language Programs

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Assessing the Effects of Service-Learning on Student Writing

This paper proposes methods to study the impact of service-learning on the writing performance cf native and non-native English speaking students in first-year college composition. Linguistic and rhetorical features commonly identified as affecting judgments of writing quality will be compared to holistic essay and portfolio ratings to describe the impact of different teaching and learning contexts on writing performance. The implications of the study will be of particular interest to L1 and L2 university composition instructors interested in learning more about service-learning and writing assessment

Climate change : a response surface study of the effects of CO2 and temperature on the growth of French beans

The possible impact of global rises in atmospheric CO2 concentration and temperature on the growth and development of French beans (Phaseolus vulgaris) was examined using growth cabinets. Five CO2 concentrations of 350, 450, 550, 650 and 750 vpm and five temperatures of 14·5, 15·5, 16·5, 17·5 and 18·5°C were tested using a fractional factorial design comprising nine treatment combinations of the two factors. Plants were grown under constant irradiance, common atmospheric humidities (vpd 0·5 kPa) and non-limiting supplies of water and mineral nutrients. The plant growth response was modelled by fitting polynomial response function curves to the times to first flower opening, first bean set, 50% maturity and the number and yield of beans. The effects of temperature were large and positive for most of the measured variables, whereas the effects of CO2 were small and negative or non-existent. Increased temperature substantially reduced the time to flowering and the time from bean set to 50% maturity and increased the number and yield of mature beans whereas increased CO2 concentration had little effect on plant growth except that bean yield was very slightly reduced. There was no significant evidence of interaction between the CO2 concentration effects and the temperature effects. The time to maturity and yield of mature beans was simulated for the 2020s (2010 to 2039) and the 2050s (2040 to 2069) using the fitted polynomial models and four climate change scenarios suggested by the UK Climate Impacts Programme. These simulations showed that, depending upon the assumed scenario, the 2020s yields could rise by 39–84% and time to maturity reduce by between 6 and 15 days whereas the 2050s yields could rise by 51–118% and time to maturity reduce by between 9 and 25 days

Predicting Broccoli Development: I. Development Is Predominantly Determined By Temperature Rather Than Photoperiod

Predictive models of broccoli (Brassica oleracea L. var. italica Plenck) ontogeny will aid farmers who need to forecast changes in crop maturity arising from variable climatic conditions so that their forward marketing arrangements can match their anticipated supply. The objective of this study was to quantify the temperature and photoperiod responses of development in a sub-tropical environment from emergence to floral initiation (EFI), and from floral initiation to harvest maturity (FIHM). Three cultivars, ('Fiesta', 'Greenbelt' and 'Marathon') were sown on eight dates from 11 March to 22 May 1997 and grown under natural and extended (16 h) photoperiods at Gatton College, south-east Queensland, under non-limiting conditions of water and nutrient supply. Climatic data, dates of emergence, floral initiation and harvest maturity were obtained. The estimated base (Tbase) and optimum (Topt) temperatures of 0 and 20 degrees C, respectively were consistent across cultivars, but thermal time requirements were cultivar specific. Differences in thermal time between cultivars during FIHM were small and of little practical importance, but differences in thermal time during EFI were large. Sensitivity to photoperiod and solar radiation was low in the three cultivars used. When the thermal time models were tested on independent data for five cultivars ('Fiesta', 'Greenbelt', 'Marathon', 'CMS Liberty' and 'Triathlon') grown as commercial crops over two years, they adequately predicted floral initiation and harvest maturity

The effect of cultural and environmental factors on potato seed tuber morphology and subsequent sprout and stem development

Seed crops of the variety Estima were grown in each of 2 years using two planting dates, two harvest dates, two plant densities and two irrigation regimes to produce seed tubers which had experienced different cultural and environmental conditions. The effects of these treatments on tuber characteristics, sprout production and stem development in the ware crop were then determined in subsequent experiments using storage regimes of 3 and 10 °C. Time of planting the seed crop affected numbers of eyes, sprouts and above ground stems in the subsequent ware crop because environmental conditions around the time of tuber initiation appeared to alter tuber shape. Cooler, wetter conditions in the 7 days after tuber initiation were associated with tubers which were longer, heavier and had more eyes, sprouts and above ground stems. In contrast, the time of harvesting the seed crop did not affect tuber shape or numbers of above ground stems and there was no interaction with tuber size. The density of the seed crop had no effect on any character measured and irrigation well after tuber initiation did not affect tuber shape, numbers of sprouts or numbers of stems. Seed production treatments, which resulted in earlier dormancy break, were associated with tubers that produced more sprouts and above ground stems, in contrast to the conventional understanding of apical dominance. Storage at 3 °C gave fewer sprouts, a lower proportion of eyes with sprouts and fewer stems than storage at 10 °C. The major effects on stem production appear to result from environmental conditions at the time of tuber initiation of the seed crop and sprouting temperature

Níquel em solos e na cultura de soja

Resumo: A soja (Glycine max [L.] Merrill) é uma das culturas de maior importância econômica no mundo e o Brasil é o maior produtor mundial dessa leguminosa. O Ni é um micronutriente essencial às plantas por ser componente estrutural das enzimas urease e hidrogenase, entretanto, poucos são os estudos sobre seu efeito na cultura da soja. Não existem critérios para adubação com Ni e são escassas as informações sobre sua disponibilidade no solo. Desta forma, os objetivos foram estudar a adubação com esse micronutriente na cultura da soja, visando estabelecer níveis críticos de Ni no solo e na planta, bem como compreender o comportamento dos teores disponíveis de Ni em solos naturais e agrícolas. O estudo foi constituido de três experimentos, sendo o primeiro em laboratório e os outros dois em condições controladas. O primeiro estudo foi destinado à avaliar a disponibilidade de Ni utilizando os extratores Mehlich-1 e DTPA em solos naturais e agrícolas, bem como verificar a relação do Ni com os atributos químicos e texturais desses solos. Os outros dois experimentos foram destinados a verificar a resposta da cultura da soja ao Ni. No primeiro experimento em condições controladas buscou-se determinar uma dose ideal para soja. Utilizou-se o cultivar BRS 360 RR em dois solos de textura contrastante submetidos à aplicação de 0,0; 0,2; 0,4; 0,8; 1,0 e 5,0 mg dm-3 de Ni. Enquanto no outro experimento o mesmo cultivar de soja foi avaliado em oito solos submetidos à aplicação de 0,0 e 0,5 mg dm-3 de Ni. Foram avaliados atividade enzimática da urease e nitrato redutase, conteúdo de clorofila, taxa fotossintética, massa seca das plantas, componentes de produtividade, análise do solo e tecido vegetal. Foram quantificados os teores de Ni disponíveis em Mehlich-1 e DTPA, teores foliares e nos grãos. Em comparação a outros micronutrientes, os teores de Ni disponíveis se mostraram bastante baixos, variando em solos agrícolas e naturais de < 0,1 a 0,54 mg dm-3 em Mehlich-1 e < 0,013 a 0,27 mg dm-3 em DTPA, com alto grau de dificuldade para sua determinação, evidenciando a necessidade de mais pesquisas para determinação de faixas de valores e níveis críticos nos solos agrícolas. Os atributos químicos e texturais dos solos, bem como as atividades agrícolas, influenciam diretamente nos teores disponíveis de Ni. Os extratores Mehlich-1 e DTPA apresentaram diferença quanto aos teores extraídos de Ni disponível, fato que se deve ao princípio de extração: dissociação para o Mehlich-1 e complexação no caso do extrator DTPA. Aspectos fisiológicos das plantas de soja foram potencializados com a aplicação de doses em torno de 0,5 mg dm-3 de Ni, entretanto não contribuíram para o aumento dos componentes de produtividade. Portanto, a aplicação de Ni nas condições estudadas não se fez necessária. A exigência de Ni pelas plantas é baixa, sendo que o teor na semente pode suprir algumas gerações. Em solos com teores disponíveis mais altos de Ni pode ocorrer redução do desenvolvimento das plantas, consequentemente, da massa seca dos grãos de soja devido efeito excessivo/tóxico desse micronutriente. O Ni não apresentou níveis críticos para os solos estudados e para a parte aérea das plantas de soja. Entretanto, teores foliares de 0,3 a 0,8 mg kg-1 de Ni, teores disponíveis de 0,2 a 0,6 mg dm-3 de Ni em DTPA e 0,4 a 0,8 mg dm-3 de Ni em Mehlich-1, podem ser tomados a princípio como sugestão aproximada de níveis de referência para Ni em solos e folhas diagnóstico de soja. Estas faixas de valores estavam associadas as maiores respostas fisiológicas ao Ni nas plantas de soja. Portanto, a disponibilidade de Ni nos solos está relacionada diretamente as características inerentes de cada classe de solo, entretanto, a resposta da soja ao Ni depende não somente do teor disponível no solo, mas também dos teores das sementes e das condições do ambiente de cultivo, fatores estes que condicionam as exigências pelas plantas durante o ciclo de desenvolvimento

Climate change: a response surface study of the effects of CO 2

The possible impact of global rises in atmospheric CO2 concentration and temperature on the growth and development of French beans (Phaseolus vulgaris) was examined using growth cabinets. Five CO2 concentrations of 350, 450, 550, 650 and 750 vpm and five temperatures of 14·5, 15·5, 16·5, 17·5 and 18·5°C were tested using a fractional factorial design comprising nine treatment combinations of the two factors. Plants were grown under constant irradiance, common atmospheric humidities (vpd 0·5 kPa) and non-limiting supplies of water and mineral nutrients. The plant growth response was modelled by fitting polynomial response function curves to the times to first flower opening, first bean set, 50% maturity and the number and yield of beans. The effects of temperature were large and positive for most of the measured variables, whereas the effects of CO2 were small and negative or non-existent. Increased temperature substantially reduced the time to flowering and the time from bean set to 50% maturity and increased the number and yield of mature beans whereas increased CO2 concentration had little effect on plant growth except that bean yield was very slightly reduced. There was no significant evidence of interaction between the CO2 concentration effects and the temperature effects. The time to maturity and yield of mature beans was simulated for the 2020s (2010 to 2039) and the 2050s (2040 to 2069) using the fitted polynomial models and four climate change scenarios suggested by the UK Climate Impacts Programme. These simulations showed that, depending upon the assumed scenario, the 2020s yields could rise by 39–84% and time to maturity reduce by between 6 and 15 days whereas the 2050s yields could rise by 51–118% and time to maturity reduce by between 9 and 25 days