Telas de sombreamento na produção de morangueiro em ambiente protegido Shading screens in the production of strawberry in greenhouse

Analisou-se a produção de duas cultivares de morangueiro, conduzido sob diferentes telas de sombreamento (coberturas) em ambiente protegido. O experimento foi realizado em estufa agrícola de aço galvanizado, com teto semicircular, coberta com filme de polietileno de baixa densidade (PEBD) de 150 &#956;m de espessura, no Setor de Horticultura da Universidade de Passo Fundo, RS. Os tratamentos constaram de um fatorial duplo com duas cultivares (Camarosa e Oso Grande) e 4 coberturas (testemunha sem tela e telas termo-refletora metálica, azul e vermelha com 40% de sombreamento) que foram distribuídas em delineamento de blocos casualizados, com 3 repetições com 20 plantas por parcela em área útil de 3 m². Foram determinados o número total e comercial de frutos e a massa fresca total e comercial e de frutos deformados por planta. Monitorou-se a temperatura do ar e a radiação fotossinteticamente ativa (RFA), sendo essa verificada em dois dias típicos (dia ensolarado e dia nublado). Considerando as médias obtidas sob a ausência e presença de telas e o total das colheitas, as produções das cultivares Oso Grande e Camarosa foram semelhantes. Na tela azul essas cultivares apresentaram a menor massa fresca.<br>The production of two strawberry cultivars achieved under different shading screens (covers) in protected environment was evaluated. The experiment was set up in galvanized steel closed greenhouse with semicircular ceiling covered with low-density polyethylene (LDPE) films 150 &#956;m thickness, in the University of Passo Fundo, Rio Grande do Sul State, Brazil. The treatments consisted of a double factorial with two cultivars (Camarosa and Oso Grande) and four covers (control without screen and metalic, blue and red thermo-reflective screens with 40% shading) which were distributed in randomized blocks lining with three repetitions with 20 plants per plot in an useful area of 3m². The total and commercial number of fruits and the total and commercial fresh mass of deformed fruits per plant were determined. Also, the air temperature and the photossintetically active radiation (PAR) were monitored, being verified in two typical days (sunny and cloudy day). Considering the averages obtained under the absence and presence of screens and the total of the crops the production of the cvs. Oso Grande and Camarosa were similar. Under the blue screen these cultivars showed the lowest fresh mass

Actividad antioxidante, compuestos fenólicos y ácido ascórbico de frutillas en dos sistemas de producción Antioxidant activity, phenolic compounds and ascorbic acid content in strawberries from two crop production systems

El objetivo de este trabajo fue determinar la influencia del sistema de producción y del período de almacenamiento de frutillas sobre la pérdida de masa, compuestos fenólicos totales, antocianinas totales, ácido ascórbico (vitamina C), actividad antioxidante y sus correlaciones. En este experimento fueron utilizadas frutillas 'Camarosa' y 'Camino Real' con madurez comercial, procedentes de cultivos en sistemas de producción orgánico y convencional, localizados en el municipio de Pelotas-RS. Los frutos fueron almacenados durante 0, 2, 5 y 8 días a 1ºC y 90-95% de HR. En general, el contenido de fenoles totales, de antocianinas totales y la actividad antioxidante aumentaron durante el almacenamiento refrigerado, mientras que los contenidos de ácido ascórbico y de masa fresca disminuyeron significativamente. Los contenidos de fenoles totales y de antocianinas totales presentaron correlación positiva con la actividad antioxidante, siendo la correlación con el contenido de ácido ascórbico negativa. Las frutillas producidas en sistema orgánico y conservadas durante cinco días, mostraron mayores valores de actividad antioxidante. Después de ocho días de almacenamiento a 1ºC, los frutos del sistema de producción orgánico presentaron menor degradación de antocianinas y de ácido ascórbico que los frutos del sistema de producción convencional.<br>The aim of this study was to determine the influence of the crop production system and storage period on weight loss, total phenolic content, total anthocyanin content, ascorbic acid (vitamin C) content, and antioxidant activity in strawberries, as well as their correlations. For this experiment, strawberry fruits of 'Camarosa' and 'Camino Real' at commercial maturity from both organic and conventional crop production systems located in Pelotas, Brazil, were used. The fruits were cold stored for 0, 2, 5, and 8 days at 1ºC and 90-95% RH. In general the total phenolic, total anthocyanin levels and antioxidant activity increased during cold storage. Ascorbic acid levels and fresh weight decreased significantly. Total phenol and anthocyanin levels showed positive correlations with total antioxidant activity, while the ascorbic acid content showed a negative correlation. Strawberries produced by the organic system and cold stored for five days showed higher values of antioxidant activity. After storage at 1ºC for eight days, strawberry fruits from the organic production system presented lesser anthocyanin and ascorbic acid degradation than the fruits from the conventional production system