The quality of red lettuce is based on the content of anthocyanin pigments, and the content of these pigments increases when the plant receives ultraviolet radiation. Lettuce crops are increasingly being grown in greenhouses to provide better quality fresh lettuce; however, both quality and productivity are affected by the type of cover used. The effects of UV-transparent and UV-blocking plastic films on the growth and quality of three lettuce cultivars (‘Casabella’ and ‘Vera’, which are both green leaf, and ‘Lollo Rosso’, which is red leaf) were investigated. The crop was cultivated at an altitude of 2576 m a.s.l. to naturally expose it to high ultraviolet radiation. The height and diameter of plants, fresh and dry weight, leaf area index, chlorophyll fluorescence, and leaf colour were determined throughout the crop cycle. Growth characteristics were not significantly influenced by the plastic film in all cultivars, probably due to the high altitude and the high solar radiation received. The UV-transparent film could increase the red colour in ‘Lollo Rosso’, and a higher commercial quality was achieved. No effect of the plastic film on the yield component was observed in the ‘Casabella’ and ‘Vera’ cultivars. The findings of this study provide guidance on what cultivar and plastic film must be used in high-altitude areas where the solar and UV radiation is high.

El manejo hídrico del cultivo de fresa es uno de los principales problemas de producción en Colombia, reflejado en las perdidas de frutos o deformación de estos. Plantas de dos variedades de fresa (Fragaria x ananassa Duch), fueron irrigadas tanto en condiciones óptimas de riego como en déficit hídrico leve, en un macro túnel en la Sabana de Bogotá. Para el manejo hídrico se realizó el seguimiento durante cinco meses de variables climáticas (temperatura, humedad relativa, radiación PAR y déficit de presión de vapor) y del cultivo (temperatura del dosel, contenido de humedad de sustrato y conductancia estomática), buscando validar mediante la correlación de estos métodos conocidos el seguimiento del estado hídrico de las plantas de fresa mediante el método del índice de estrés hídrico del cultivo - CWSI. Se concluye que las imágenes termográficas mediante el CWSI son una herramienta válida y completa para la detección de estrés hídrico en cultivos protegidos de porte bajo, dada la alta correlación con otros métodos, y la ventaja que ofrece de relacionar el seguimiento de las características fisiológicas del cultivo con las variables climáticas que lo afectan.

In this study, the spectral responses obtained from a Typic Red Hapludox (oxisol) were analyzed under different uses and occupations: Ficus elastica cultivation, Citrus + Arachis association cultivation, transitional crops, forest, Mangifera indica, Anacardium occidentale, Elaeis guineensis (18 years), Brachiaria decumbens, Brachiaria brizantha, and Musa × paradisiaca + Zea mays at the La Libertad Research Center in the department of Meta in Colombia (4°04′ North latitude, 73°30′ West longitude, 330 MAMSL). Sampling was performed with four random replicates of the horizon A and B to determine the contents of organic carbon (CO), pH, exchangeable acidity (Ac. I), cation exchange capacity (Cc), P, Ca, Mg, K, Na, sand, lime, and clay and spectral responses were obtained in the visible band (VIS), near infrared (NIR), and infrared (MIR) for each sample under laboratory conditions. A comparison was made between the obtained spectra, determining the main changes in soil properties due to their use and coverage. Variation of soil characteristics such as color, organic carbon content, presence of ferrous compounds, sand, silt, and clay content and mineralogy allow the identification of the main spectral changes of soils, demonstrating the importance of the use of reflectance spectroscopy as a tool of comparison and estimation between physical-chemical properties of the soils.