Marcelo Augusto de Aguiar e Silva

Agronomic performance of soybean cultivars in an agroforestry system1

The increasing demand for food, fibers and agro-energy, along with production upscaling, search for practical solutions in production processes and advancement in mechanization, have transformed modern agricultural activities into simplified and standardized systems. However, this model has been considered insufficient and has shown signals of saturation, because of excessive demands for energy and natural resources, which elevate production costs and increase risks of economic failure (Reynolds et al. 2007, Balbino et al. 2011, Nair 2011, Pezarico et al. 2013). ABSTRACT RESUMO

Substrates and irrigation levels for growing desert rose in pots

In the past decades, desert rose has become a very popular ornamental plant, especially among collectors, due to its exotic and sculptural forms. However, it has been grown on a commercial scale only recently, and little is known about how to best manage it as a container-grown plant, or even which potting medium (substrate) to recommend. Therefore, the aim of this study was to investigate the interactions between potting media and irrigation levels for growing desert rose as a potted ornamental plant. The experiment was conducted in a greenhouse using a 6 x 2 factorial arrangement with six replications, six potting media and two irrigation levels. The mixes were characterized by measuring their physical properties, specifically the density and water retention capacity (WRC), as well as chemical properties, such as the pH and electrical conductivity (EC). After 210 days, plant growth and plant water consumption were evaluated and measured. A lower dry density for the vermiculite mixes was observed in comparison to that for the sand mixes. However, WRC ranged from 428 to 528 mL L-1 among the mixes, values considered close to ideal. In general, plant growth exhibited higher increases in mixes consisting of coconut fiber + sand or vermiculite, regardless of the irrigation level. Mixes of vermiculite + coconut fiber and sand + coconut fiber can be used to grow desert rose in pots, as long as irrigation is used to maintain the moisture content of the potting medium (mix) between 60-70% and 80-90% of the WRC.

Epidemias de ferrugem asiática no Rio Grande do Sul explicadas pelo fenômeno ENOS e pela incidência da doença na entressafra

Estudou-se a interferencia da variabilidade da variabilidade climatica e do numero de relatos de ferrugem asiatica na entressafra sobre a epidemia da doenca no estado do Rio Grande do Sul, durante 11 safras agricolas. A ocorrencia da doenca foi obtida a partir de relatos apresentados no Consorcio Antiferrugem e dividida entre os periodos “Safra”, “Entressafra” e “Ano Todo”. Os dados das epidemias foram testados para correlacao, via regressoes polinomiais lineares e quadraticas, com as variaveis climaticas: precipitacao pluvial, indice padronizado de precipitacao - SPI, indice de oscilacao sul - IOS e anomalia da Temperatura na Superficie do Mar - SST no Oceano Pacifico Tropical e numero de ocorrencias da doenca no periodo de entressafra. Os indices que melhor explicaram a variacao das ocorrencias da doenca para o periodo “Ano Todo” foram o SST e IOS, com coeficientes de determinacao (R2) de 0,94 e 0,59, respectivamente. As ocorrencias de ferrugem no periodo “Entressafra” influenciaram positivamente nas ocorrencias no periodo “Safra”.

Effects of Different Numbers of Fungicide Application on the Proximate Composition of Soybean

This study aimed to evaluate the effect of strobilurin (pyraclostrobin) + triazole (epoxiconazole) fungicides application on the proximate composition of soybeans. Six treatments of varying numbers of fungicide applications following soybean germination, termed T1 (control), T2, T3, T4, T5, and T6, were assessed for this experiment. Based on the results, there were only minor differences in the proximate composition of soybeans in terms of moisture, ash, crude protein, and total lipid contents. In contrast, there were large effects on the contents of phenolic compounds and the levels of phytosterols and tocopherols, which varied greatly among the fungicide application treatments. Multivariate statistical analysis was applied to identify critical issues regarding the potential for the production of soybeans enriched in phenolic compounds, tocopherols, and essential fatty acids (α-linolenic and linoleic acids, representatives of the omega-3 and omega-6 families, respectively) associated with the number of sprayings applied during the development of soybean crops.