Ingenieria Química

El científico interesado en medidas de absorción en las regiones ultravioleta, visible e infrarrojo cercano no dispone de cien o más modelos de instrumentos para elegir. Algunos son sencillos y baratos (unos cientos de dólares); otros son equipos complejos, informatizados cuyo precio asciende y supera los 30.000 dólares. Para muchas aplicaciones, los instrumentos más sencillos proporcionan información tan rápida y satisfactoria como la obtenida con los equipos más sofisticados. Por otra parte, los instrumentos más complejos se han desarrollado para realizar tareas difíciles, que requieren mucho tiempo, o imposibles de realizar con los más sencillos. Los instrumentos para medir la absorción de radiación ultravioleta, visible y en el infrarrojo cercano están compuestos por uno o más de los siguientes componentes: (1) Fuentes, (2) selectores de longitud de onda, (3) recipientes para la muestra, (4) detectores de radiación y (5) procesadores de señal y dispositivos de lectura.

Several vineyards in Rías Baixas and one in the Ribeira Sacra (Spain) were monitored and the spatial pattern of leafroll-diseased grapevine was analysed at several dates. Unidimensional aggregation analysis (ordinary runs), bidimensional analysis, and disease gradients analysis were used as methods of study of spatial aspects of epidemics of GLRaV. At very low insect populations the mealybug Planococcus citri transmitted the GLRaV-3 from infected plants to healthy ones planted between them in an experimental plot at Beluso; an initial focus of leafroll-infected grapevines was detected 2 years after planting at the area where the vectors had been located infesting the old plants. Within 8 years some new foci appeared and coalesced, and the incidence reached >80%. In three commercial plots where no vectors were observed, the spatial analysis of the diseased plants showed three different situations. In Meaño, the study of the evolution of the spatial patterns of diseased plants between 1992 and 2005 suggested slow vectorial field transmission of GLRaV-3. In Goián the analysis for only 2 years suggested random distribution; therefore the viruses were arriving with the planting material, but the runs analysis of some lines suggested incipient spread of GLRaV-3. In Portomarín the incidence of both GLRaV-2 and 3 was low and their distribution was random, without any evidence of field spread. These examples of the study of the spatial analysis of leafroll-infected plants may be helpful to determine whether or not spread of the viruses is occurring, and the best control measures to take.