El objetivo de este estudio fue evaluar el efecto de tratamientos de boro edáfico y frecuencia del calcio foliar en floración, sobre la producción y ocurrencia de la pudrición apical de híbridos de tomate italiano, cultivados en el sistema convencional en dos temporadas de cultivo. Se realizaron dos experimentos en el área experimental perteneciente a la Universidade Federal de Santa Maria, campus de Frederico Westphalen (Brasil), en los años 2012 y 2013. El diseño experimental fue de bloques al azar con un arreglo factorial 2×2×3×3 cuyo factores fueron dos híbridos (San Vito y Neptuno), en dos épocas de cultivo (primavera-verano y verano-otoño), tres dosis de boro (0; 2,0 y 4,0 g/planta) y tres frecuencias de aplicación de calcio (ausencia de aplicación, aplicación semanal y quincenal) y cuatro repeticiones. El trasplante de plántulas se realizó el día 04 de septiembre de 2012 para la primavera-verano y el 26 de enero para el verano-otoño. El híbrido Neptuno es más productivo en comparación con el híbrido San Vito, pero más susceptible a la pudrición apical. Las dos épocas de cultivo pueden ser recomendadas para el cultivo del tomate italiano en Rio Grande do Sul, aunque el cultivo de primavera-verano presenta mayor productividad cuando se compara al verano-otoño. La frecuencia de aplicación quincenal de CaCl2 al 0,6% se constituye en la mejor opción de manejo de fertilización, en el sentido de obtener mayor productividad y menor número de frutos con incidencia de pudrición apical. El incremento de la dosis de boro condiciona mayor número de frutos por planta y aumento de la productividad.

Effect of season and irrigation on the chemical composition of Aloysia triphylla essential oil Aloysia triphylla is an aromatic plant used in several industrial sectors, owing to the chemical properties of its essential oil. Biosynthesis of organic compounds is influenced by the growth conditions. As such, temporal and spatial variation affect the chemical composition of essential oils. We hypothesized that: i) the chemical composition of A. triphylla essential oil is influenced by differences in irrigation and season; and ii) the major components of A. triphylla essential oil do not vary between treatment conditions. To test these hypotheses, we determined the chemical composition of A. triphylla essential oil as a function of four seasons crossed with four irrigation levels. A completely randomized experimental design with a randomized block in a 4 × 4 factorial scheme, representing the four seasons of the year (summer, autumn, winter, and spring) and four irrigation levels (50%, 75%, 100%, and 125% of the reference evapotranspiration), was used with four replicates. Our results show that the chemical composition of A. triphylla essential oil varied with the two study factors, of which season was the major factor. The highest concentrations of constituents classified as monoterpene and sesquiterpene were observed in the summer season, and the highest constituents of the other group of compounds were observed in winter. In addition, the major components of the essential oil were α-citral, limonene, and β-citral, and their levels were the highest during winter.

. Caracterização fenológica, filocrono e requerimento térmico de tomateiro italiano em dois ciclos de cultivo. Horticultura Brasileira 35: 089-096.

Shading greenhouse may be an effective method to achieve a suitable environment for crop growth in subtropical regions. The aim of this study was to evaluate the production of leaves and branches as well as the morphological parameters of height and leaf area of the species Aloysia triphylla, under different shading levels throughout the seasons of the year. A randomized block design in factorial scheme 3x4x6, i.e., three levels of shading (0%, 30% and 50%), four seasons (summer, autumn, winter and spring) and six collection in each season (15, 30, 45, 60, 75 and 90 days after the beginning of each season), with four replications, was used. All evaluations were performed in 2012, since in the first evaluation (summer) the plants had 65 days after transplanting and the last evaluation (spring) the plants had 315 days after transplanting. The dry matter of leaves and branches, leaf area, and plant height were evaluated. The production of the dry matter of leaves and branches, and height and leaf area for the species Aloysia triphylla is influenced by shading levels and the seasons of the year. The variables are highly dependent on the seasonality of meteorological elements such as temperature, solar radiation, rainfall, and frost. In an environment with 0% shading, the dry matter production of leaves was 60.8 % higher in the spring, than those observed for the 30% and 50 % of shading, while this levels resulted higher production in the summer. We showed that the use of shading screens in order to attenuate the solar radiation in places or seasons where there is high light intensity is an effective method to achieve higher production of leaves, which is important source for the oil production.

No abstract