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Biodiesel has a lipid origin; thus, antioxidants commonly used in oils and fats have been adopted for the improvement of the oxidative stability of biodiesel. However, these antioxidants have not shown the same efficiency when they are applied to biodiesel. This fact points out the need to investigate additives that warrant the oxidative stability of biodiesel, especially during long storage periods. In this paper, antioxidant formulations were developed for application in biodiesel, from blends including the synthetic antioxidants butylated hydroxytoluene (BHT), tert-butylhydroquinone (TBHQ), the chelating agent citric acid, and organic rosemary extracts. The antioxidants were applied at different concentrations and combinations and were evaluated by the Rancimat method, EN 14112, and by the pressurized PetroOXY method. The results showed that for ethanol soybean biodiesel, the antioxidant compositions formed by TBHQ (2000 mg kg −1 ) and citric acid (500 mg kg −1 ) and by the chloroform rosemary extract (2000 mg kg −1 ) and citric acid (500 mg kg −1 ) were the most effective in delaying the oxidative process, in a manner independent of the evaluation method. For the methanol cottonseed oil biodiesel, the best result was obtained using the combination of 1500 mg of TBHQ with 1500 mg of ethanol rosemary extract. However, the formulations using low concentrations of rosemary ethanol extract and citric acid induction periods of >6 h were obtained, reaching the limit specified by European Standard EN 14214.

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O objetivo desse trabalho foi adaptar e testar a eficiência da metodologia para teste de condutividade elétrica na avaliação da qualidade de sementes de Moringa oleifera Lam. Para a caracterização fisiológica das sementes, quatro lotes de sementes foram avaliados pelos testes de germinação, emergência de plântula, índice de velocidade de emergência, primeira contagem de emergência, comprimento e massa seca de plântulas e teste de frio. O teste de condutividade elétrica foi avaliado a 25 °C, em 4, 8, 12, 16 e 24 h de imersão em 75 mL e 125 mL de água destilada, utilizando-se 25 e 50 sementes. Empregou-se o delineamento inteiramente casualizado. Os melhores resultados foram obtidos quando utilizou-se 50 sementes imersas em 75 mL ou 125 mL de água destilada por 4 h. O teste de condutividade elétrica adaptado para moringa mostrou-se eficiente em ranquear os lotes de sementes em diferentes níveis de vigor, podendo ser usado com eficiência na avaliação da sua qualidade fisiológica.

Objective: Evaluate the development and gas exchange of pre-sprouted sugarcane seedlings in different substrates. Study Design: A randomized complete block design was used with two genotypes, three types of substrate (2 x 3), four replicates and five plants per replicate, totaling 120 plants. Location and Duration of Study: Department of Crop Sciences of the Center for Agrarian Sciences, Universidade Federal de Paraíba in the city of Areia, Brazil, between August and October 2018. Methods: The following were the treatments: T1 – genotype 1 in commercial substrate; T2 – genotype 1 in commercial substrate + bovine manure; T3 – genotype 1 in bovine manure + sand; T4 – genotype 2 in commercial substrate; T5 – genotype 2 in commercial substrate + bovine manure; T6 – genotype 2 in bovine manure + sand. Variables analyzed: height, diameter, dry mass of shoot and root and physiological response of seedlings. Results: A significant difference at the 1% level was found for the dry matter of the seedling roots among treatments with difference substrates. A significant difference at the 1% level was also found for shoot length and a significant interaction at the 5% level was found between genotype and substrate for this characteristic. Significant effects were found with regard to the rate of photosynthesis, stomatal conductance, transpiration and carboxylation efficiency. Conclusion: The substrate with manure + sand favored the accumulation of root dry matter and shoot length. Genotype 1 exhibited its best performance with regard to photosynthesis and stomatal conduction in the treatment with the commercial substrate and demonstrated greater carboxylation efficiency than genotype 2, independently of the substrates. The pre-sprouted seedling production system needs to be explored further to obtain greater information regarding the nutritional requirements and characteristics of the genotypes.

Visando fornecer subsídios às pesquisas e cultivos dos consórcios de caupi-hortaliça com beterraba e adubação com espécies espontâneas, o objetivo desse trabalho foi determinar a quantidade de flor-de-seda que deve ser incorporada ao solo com a finalidade de promover o melhor rendimento dessas culturas. O experimento foi conduzido na Fazenda Experimental Rafael Fernandes, localizada no distrito de Alagoinha, Rio Grande do Norte. O delineamento experimental utilizado foi em blocos casualizados com 4 tratamentos (10, 25, 40 e 55 t ha-1 doses de adubos de flor-de-seda) e 5 repetições. Para as características de peso de 100 grãos, número de grãos por vagens, peso dos grãos frescos e das vagens frescas de caupi-hortaliça consorciada com beterraba, obtiveram altos índices quando adicionaram-se 53 t ha-1 de flor-de-seda; 46,49 t ha-1 de flor-de-seda; 46,89 t ha-1 de flor-de-seda e 46,98 t ha-1 de flor-de-seda, respectivamente. Na beterraba, foram encontradas respostas crescentes para altura de plantas, número de folhas, produtividade comercial e total, e produtividade classificada, nas quantidades de 55 t ha-1; 44,21 t ha-1; 18,59 t ha-1; 22,23 t ha-1 e 55 t ha-1, respectivamente. Para os indicadores econômicos, renda bruta, renda líquida, taxa de retorno e índice de lucratividade, foram obtidos: R$ 31.784,46; R$ 10.732,57; 1,54 e 35,28%, respectivamente. O consórcio entre a beterraba e o caupi-hortaliça mostrou-se eficiente e os melhores desempenhos agronômicos foram obtidos na incorporação de 55 t ha-1 e 47 t ha-1 de flor-de-seda.

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Luffa operculata (L.) is a native Brazilian biome plant used for the treatment of respiratory diseases. Although Brazil’s flora comprises 67% of the world’s plants, only 8% of Brazilian plant species are studied each year. The studies indicate that climate change in tropical biomes intensifies the increase in salinized areas by about 10% per year for several reasons, including high temperatures, low rainfall and high evapotranspiration rates, due to surface water scarcity. Therefore, the aim of the present study was to evaluate the germination behavior and vigor of L. operculata seeds submitted to saline stress at different temperatures. To simulate salt stress conditions, sodium chloride was applied at 0.0; 3.0; 6.0; 9.0 and 12.0 dS m-1, at 25, 30, 35, 20-30 °C, with treatments distributed in a 5 x 4 factorial scheme (five levels of osmotic potential and four temperatures), using four replications. The seeds were then evaluated concerning water content, germination tests, first counts, germination speed index and seedling root and shoot lengths. At 30 and 35 °C, the seed germination and vigor of L. operculata were less affected up to an osmotic potential of 9.0 dS m-1, where it is considered a moderate salinity tolerance. At 35 ºC, the germination uniformity was reduced to 98 and 93% by applying the 6 and 9 dS m-1 solutions, respectively. For the same temperature, the germination velocity remained 6.09 (IVG) until the saline potential of 9.0 dS m-1