RESUMOAvaliaram-se a produção e o valor nutritivo do capim-coastcross (Cynodon dactylon) sob cinco doses de nitrogênio -0, 100, 200, 300 e 400kg/ha.ano -e duas idades de rebrotação -28 e 42 dias. Os tratamentos foram arranjados em esquema fatorial, em blocos ao acaso, com três repetições. A adubação com nitrogênio (N) foi parcelada em três aplicações, realizadas logo após os cortes. A densidade populacional de perfilhos apresentou padrão de resposta quadrático em resposta à aplicação de N. A produção de forragem do capimcoastcross variou de 8,0 a 17,2t/ha.ano para as doses de 0 a 400kg/ha.ano de N, apresentando resposta linear positiva com a adubação nitrogenada. Maiores valores de relação folha:colmo (RFC) foram obtidos em cortes mais tardios, na ausência de aplicação de N. Em geral, as doses crescentes de N diminuíram linearmente a RFC do capim-coastcross. A adubação nitrogenada aumentou linearmente os teores de proteína bruta (PB), observando-se maior eficiência de resposta na idade de 28 dias. Aumentos na digestibilidade in vitro da matéria seca em resposta à aplicação de doses crescentes de N somente ocorreram em plantas mais jovens, aos 28 dias de rebrotação. O teor de fibra em detergente neutro reduziu linearmente com a adubação nitrogenada. O efeito da adubação nitrogenada no valor nutritivo do capim-coastcross depende da idade de rebrotação dessa forrageira. Com a aplicação de maiores doses de N e sob condições favoráveis de crescimento, o pasto de capim-coastcross deve ser manejado com frequência de desfolhação de 28 dias.Palavras-chave: Cynodon dactylon, digestibilidade, fibra em detergente neutro, número de perfilho, proteína bruta ABSTRACTThe production and nutritive value of the bermudagrass cv. coastcross under five different nitrogen doses (0, 100, 200, 300 and 400kg/ha.year)

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Cadmium (Cd) accumulation by water hyacinth and salvinia under different sulfur (S) concentrations was studied. Plants were exposed during six days to 0 and 5 μM of Cd in nutrient solution with 0, 400 and 800 μM of S, and then S and Cd contents in tops and roots were determined. Sulfur content was always higher in S-treated plants, independent of the presence of Cd. Cadmium content in Cd-treated plants increased with the addition of S to the nutrient solution in both species. Water hyacinth roots accumulate an average of 1.4 time more Cd than those of salvinia. The increase in S concentration from 400 to 800 μM, however, usually did not result in additional increase in S nor in Cd accumulation. The molar Cd/S ratio after Cd treatment reached average values of about 4.8 in roots and 2.6 in tops in comparison to their respective controls. Both species, therefore, were Cd accumulators and the accumulation was larger in the roots under presence of S. Since water hyacinth produced larger root mass and accumulated more Cd, it showed larger capacity to remove Cd from aquatic systems contaminated with this metal, especially if S is available.

Tribolium castaneum is an insect that occurs worldwide and it is a pest that attacks stored products, in particular, grains and seeds. The adult and immature forms are categorized as secondary pests which feed on grains or seeds previously damage in storage conditions. The objective of this study was to describe the type of damage caused by adults and immature of T. castaneum in Brazil nuts and identify the type of damage caused by Coleoptera. It was also verified whether the shell can protect the almond from the attack of this pest. The lesions inflicted by this insect starts as a scratched surface, which evolves into galleries and even injuries capable of modifying the original shape of the almond. Due to its capacity to promote considerable damage with consequent losses in the value of the nuts, T. castaneum may be listed among pests of Brazil nut categorized as primary pest by its ability to initiate injuries in the intact almond.

Cryopreservation is a promising technique for long term conservation of sugarcane's genetic resources which could be used in breeding programs. Preculture is a key step for success this technique. The purpose of this study was to evaluate the effect of sucrose concentrations and preculture period on dessication tolerance of sugarcane tissue dehydrated to 30, 20 and 10 % moisture. Sugarcane shoot tips were encapsulated in sodium alginate and precultured in a liquid culture medium with 0.3, 0.5, and 0.75 M sucrose. Preculturing in 0.3 M sucrose was ideal to induce desiccation tolerance in tissue. This sucrose concentration reduced the percentage of electrolytic leakage. Shoot tips were sensitive to a sucrose concentration of 0.75 M, resulting in low survival rates after desiccation. Preculturing in 0.5 M sucrose resulted in a higher survival rate after drying for 5.7 and 7.45 h. The percentage of electrolytic leakage was high when shoot tips were desiccated after preculturing in 0.5 and 0.75 M sucrose.