The application rate of plant-protection products is indicated as a concentration or amount of product per area. Greenhouse crops grow swiftly, and an application rate based on a fixed amount of product per hectare can result either in large losses and overdoses when the plants are small or to be insufficient when the plants are fully developed. To solve these problems, the application rates of plant-protection products need to be adapted to the plant mass present in the greenhouse when the spray is applied. Two models were developed to estimate the leaf area based on easily measured geometric data of the vegetation in a greenhouse tomato crop. The model based on the PRV (Plant Row Volume) had that best results. The calculation of the volume application rate from the PRV has resulted in a reduction of more than 30 % of the quantity of plant protection product sprayed, without decreasing yield. The PRV of a greenhouse tomato (Lycopersicon esculentum Mill.) is an easily measured parameter that enables the estimation of the leaf area index and the use of application strategies adapted to the changes in the plant canopy, saving major amounts of plant protection product used, compared to the conventional system.

In México, blue maize (Zea mays L.) grains are destined preferably for the elaboration of diverse foods among which tortilla is the most common. Anthocyanins are the pigments responsible for grain color, nevertheless, their variability among maize used for torilla elaboration is scarcely known. Therefore, 18 samples of blue/purple maize grains (Zea mays L.) of Chalqueño (CHAL), Elotes Cónicos (EC) and Bolita (BOL) races were analyzed to determine their anthocyanin content (AT), total soluble phenols (TSP), and antioxidant activity (AA), as well as the color and size of the grain. The chromatographic profile of their anthocyanins and aglycons was also determined. A completely randomized experimental design was used. Results showed a reduced variability in AT and TSP within the races but variability was higher among the races. The average AT contents per race were 855 ±140, 1205±130 and 423±95 mg ECG/kg MS in CHAL, EC and BOL, respectively. There was a significant correlation (r²=0.89) between AT and AA. The races presented a similar anthocyanin profile characterized by the predominance of acylated anthocyanins (>60 %) derived from cyanidin, which was the most abundant aglycone. The weight of 100 seeds and the color of the grain (L and chrome) showed a highly significant correlation with the AT content. Due to the high AT content and a chromatographic profile dominated by cyanidin derivatives, these maize varieties are an attractive raw material for the elaboration of food products with high antioxidant content.

En México los maíces (Zea mays L.) de grano azul se destinan preferentemente a la elaboración de diversos alimentos dentro de los cuales la tortilla es el más común. La variabilidad en el contenido de antocianinas, que son los pigmentos responsables de la coloración, entre los maíces destinados para este fin, se conoce poco. Por tanto, se analizaron 18 muestras de grano de maíz azul/morado (Zea mays L.) de las razas Chalqueño (CHAL), Elotes Cónicos (EC) y Bolita (BOL) para determinar su contenido de antocianinas (AT), fenoles solubles totales (FST) y actividad antioxidante (AA), así como su color y tamaño de grano. También se determinó el perfil cromatográfico de sus antocianinas y agliconas. El diseño experimental fue un completamente al azar. Los resultados mostraron variabilidad reducida en AT y FST dentro de las razas y mayor entre razas. Los contenidos promedio de AT por raza fueron 855 ±140, 1205±130 y 423 ±95 mg ECG/kg MS en CHAL, EC y BOL. Hubo una correlación significativa (r²=0.89) entre AT y AA. Las razas presentaron las mismas antocianinas y el perfil estuvo caracterizado por predominancia de antocianinas aciladas (>60 %) derivadas de cianidina, que fue la aglicona más abundante. El peso de 100 semillas y color del grano (L y croma) mostraron correlación altamente significativa con el contenido de AT. Debido al contenido alto de AT y un perfil cromatográfico dominado por derivados de cianidina, estos maíces son una materia prima atractiva para elaborar productos alimenticios altos en antioxidantes.

The integration of renewable energy sources into greenhouse crop production in southeastern Spain could provide extra income for growers. Wind energy could be captured by small to medium-sized wind turbines, gas could be produced from biomass, and solar energy could be gathered by solar panels. The aim of this study was to examine the effect of flexible solar panels, mounted on top of a greenhouse for electricity production, on yield and fruit quality of tomatoes (Solanum lycopersycum L., cv Daniela). This study was undertaken in a commercial raspa y amagado greenhouse, typical of the Almería region (Spain). Tomato plantlets were planted at a density of 0.75 plants m-2. The flexible solar panels were mounted on two parts of the roof in different arrangements (T1 and T2), each blacking out 9.8 % of its surface area. A control area (T0 arrangement) was fitted with no panels. No difference was found in terms of total or marketable production under these three arrangements, although fruit mean mass and maximum diameter of T0 were significantly greater than T1 and T2. Fruit in T0 matured earlier with more intense color compared with those in T1 and T2. However, these differences had no effect on price as the tomatoes produced under three conditions fell into the same commercial class (G class; diameter 67-81 mm). Solar panels covering 9.8 % roof area of the greenhouse did not affect yield and price of tomatoes despite of their negative effect on fruit size and color.