RESUMO: A sorção de pesticidas no solo é o principal fator responsável por regular o destino de pesticidas no ambiente, afetando a degradação microbiológica e química, volatilização e lixiviação. O principal objetivo deste trabalho foi estudar o efeito da fase orgânica de solos vulcânicos sobre a sorção de pesticidas agrícolas. A sorção e dessorção de oito solos vulcânicos cujos constituintes flúvico e húmico de sua matéria orgânica eram variáveis. Os resultados mostraram que, para todos os pesticidas, a sorção foi bem descrita por uma isoterma de Freundlich, e os valores 1/nads indicam que o mecanismo de sorção poderia ser explicado principalmente por reações físicas em todos os solos. Carbaryl e flumioxazin foram mais adsorvidos, com Kf média de 7,78 e 7,16 mL g-1, enquanto hexazinone e metsulfuron-methyl foram os pesticidas mais lábeis, com Kf de 0,86 e 0,81 mL g-1, respectivamente. A fração orgânica do solo foi o principal fator relacionado à sorção de todos os pesticidas estudados. Especificamente, o teor de ácido húmico regulou a atração entre o pesticida e o solo, principalmente através dos grupos carboxílicos.

ABSTRACT: Pesticide soil sorption is a primary factor that influences the fate of pesticides in the environment, affecting regulation of microbiological and chemical degradation, volatilization and leaching. The main goal of this research was to study the effect of the organic phase of volcanic soils on sorption of agricultural pesticides. Sorption and desorption of eight agricultural pesticides were studied on eight volcanic soils that varied in the fulvic and humic constituents of their organic matter. For all pesticides, sorption was well described by a Freundlich isotherm where 1/nads values indicated that the sorption mechanism could be mainly explained by physical reactions in all soils. Kf values for carbaryl and flumioxazin were the highest with average values of 7.78 and 7.16 mL g-1, respectively. By contrast, hexazinone and metsulfuron-methyl had the lowest average Kf: 0.86 and 0.81 mL g-1, respectively, indicating that they were the least attracted to the soils. The organic fraction of the soil was the main soil factor related to the sorption of all study pesticides. Particularly, humic acid content regulated the sorption between pesticide and soil, especially through the carboxylic groups.

An experiment was carried out to evaluate the effects of different levels of water application during post setting and post veraison on wine quality of cv. Cabernet Sauvignon (Vitis vinifera L.) during the 2000-2001 and 2001-2002 growing seasons. The vineyard is located in the Pencahue Valley, VII Region of Chile (35º22' S lat; 71º 47' W long). The 7 year-old vineyard was drip irrigated and trained in a vertical shoot positional system. Irrigation treatments were the application of 40, 70 and 100% of the real evapotranspiration (ETreal) during post setting and post veraison. The results showed that the best combination for wine quality was obtained by restricting water applications to 40% ETreal during post setting and 70% ETreal during post veraison, with significant increments in the global quality and wine sensory attributes. On the contrary, the worst wine quality (higher titratable acidity and low total concentrations of phenols and anthocyanins) was obtained with a water application of 100% of the ETreal during the whole growing period.

Se llevó a cabo un experimento para evaluar el efecto de diferentes niveles de reposición hídrica aplicados en post cuaja y en post pinta sobre la calidad del vino en el cv. Cabernet Sauvignon (Vitis vinifera L.) durante la temporada de crecimiento 2000-2001 y 2001-2002. El viñedo está localizado en el Valle de Pencahue, VII Región de Chile (35º22' lat. Sur; 71º47' long. Oeste). El viñedo de 7 años de edad fue regado por goteo y conducido en espaldera simple. Los tratamientos de riego consistieron en la aplicación de 40, 70 y 100% de la evapotranspiración real de la vid (ETreal) durante los períodos de post cuaja y de post pinta. Los resultados mostraron que la mejor combinación de calidad de vinos fue obtenida al aplicar restricciones hídricas del 40% durante post cuaja y 70% durante post pinta, con incrementos significativos de la calidad global y atributos sensoriales del vino. Por el contrario, la menor calidad de vino (alta acidez titulable y baja concentración de polifenoles y antocianinas totales) fue obtenida con una aplicación de agua del 100% de la ETreal para todo el período de crecimiento.