Cadmium (Cd) is toxic to plants and animals, making it necessary to develop strategies that seek to reduce its introduction into food chains. Thus, the aim of this study was to investigate whether silicon (Si) and selenium (Se) reduce Cd concentrations in Pfaffia glomerata medicinal plant and attenuate the oxidative stress promoted by this metal. These plants were cultivated in hydroponics under the following treatments: control (nutrient solution), 2.5 μM Se, 2.5 mM Si, 50 μM Cd, 50 μM Cd + 2.5 μM Se, 50 μM Cd + 2.5 mM Si. After 14 days of exposure to treatments, leaves and roots were collected for the determination of dry weight of shoot and roots, Cd concentrations, chlorophyll and carotenoids content, and biochemical parameters (lipid peroxidation and guaiacol peroxidase and superoxide dismutase activities). The data were submitted to analysis of variance and means were compared with Scott-Knott test at 5% error probability. Roots of P. glomerata plants showed a significant reduction on dry weight accumulation when exposed to Cd. However, both Se and Si promoted a significant reduction of deleterious effects of Cd. The Cd concentrations in the tissues were reduced in the presence of Se or Si. Plants treated with Cd together with Se or Si presented higher pigment content than those with only Cd, thus showing a reduction in the negative effects caused by this element. In the treatments in which Se and Si were added in the growth medium together with Cd, an activation of superoxide dismutase and guaiacol peroxidase enzymes was observed in the roots and shoot, which may have contributed to lower lipid peroxidation. Thus, Se and Si reduce Cd concentrations and have potential to ameliorate Cd toxicity in P. glomerata plants, which can be used to increase productivity and quality of medicinal plants.

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The objective of this work was to verify the nutritional efficiency to phosphorus (P) as well as the responses of the use of P for three potato clones in soil and soilless cultivation (semi hydroponic). For this purpose, the Asterix, SMIC 148-A and SMINIA 793101-3 clones were evaluated under high and low P levels in soil growing (70 and 560kg P2O5 ha-1) and in soilless cultivation using sand as substrate (2.32 and 23.2mg P L-1 of nutritive solution). Rooting efficiency, absorption, translocation and use of P, fresh tuber mass, total dry mass and harvest index were evaluated in the clones. Each clone responds differently to the growing systems used in terms of nutritional efficiency for P. In both growing systems, the Asterix, SMIC 148-A and SMINIA 793101-3 clones did not show any increase in the absorption efficiency and in the efficiency of using P to compensate for the low level of P, which may have caused the reduction in total dry mass under low P. The restriction of P causes a reduction in tuber fresh mass for the Asterix and SMINIA 793101-3 clones in the two growing systems tested and for the SMIC 148-A clone only in soilless cultivation. Asterix is the clone with the highest harvest index under low P in the field, even without differing from the others in soilless cultivation

Neste trabalho apresentamos os resultados iniciais do projeto de extensão homônimo ao título. Que tem como objetivo compartilhar com os produtores rurais e o corpo técnico das empresas do setor tabacaleiro, boas práticas silviculturais para florestas energéticas destinadas à produção de lenha para cura e secagem das folhas de tabaco em unidades de cura. As ações envolvem a instalação de florestas demonstrativas, a produção de materiais técnicos e o compartilhamento de informações com agentes do setor. Num contexto de possível escassez e altos custos de matéria prima, o projeto possibilita o desenvolvimento de estratégias e ferramentas de extensão direcionadas para a melhoria da qualidade da produção florestal associada à cultura do tabaco, melhoria da segurança energética das propriedades, diversificação de produção e renda para o produtor, além da proteção de florestas nativas.

Desiccation practiced during the preharvest period contributes to mechanized seed harvesting. This work aimed to verify whether wheat preharvest desiccation influences the morphological and physiological characteristics of the seedlings produced from the seeds of desiccated plants. The preharvest treatments included a combination of herbicides (glufosinate-ammonium, glyphosate, and paraquat) and phenological application stages (Zadoks: 83, 85, 87, and 92), as well as a control treatment (without application). Two wheat cultivars were used (BRS Parrudo and TBIO Sinuelo). Herbicide applications were observed to decrease the length and projected area of the shoots by 52 and 46%, respectively, as well as reduce the length, surface area and root volume when compared to the control treatment without application. The hydrogen peroxide concentration, as well as the enzymatic activity of guaiacol peroxidase, was observed to rise only in the treatments where the herbicides were applied. Physiologically, an increased hydrogen peroxide output was revealed, while the guaiacol peroxidase enzymatic activity increased in both cultivars, but with no effect noted in the superoxide dismutase enzymatic activity. The shoot and root morphology were negatively influenced, showing a rise in the enzymatic activity and hydrogen peroxide concentration in the seedlings from the desiccated plants.

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