Resumo O número de egressos do ensino superior aumentou de cerca de 480 mil, em 2002, para mais de um milhão, em 2012. O panorama do mercado de trabalho para o profissional formado nas instituições de Ensino Superior brasileiras, gerado a partir da consulta a dados públicos no período de 2002 a 2012, indica desvalorização da mão de obra qualificada, decréscimo no número de empregos de maior remuneração, e um déficit de mais de 450 mil empregos de nível superior. Esses dados deixam claro que o nível de profissionalização dos trabalhadores deve crescer concomitantemente a ações que permitam o acesso desses profissionais ao mercado de trabalho. Nesse contexto, a importância dos projetos do governo e da universidade são inquestionáveis, sendo necessário o aprimoramento dos mecanismos de interação entre universidade, empresa e governo, de forma a viabilizar o sucesso dos programas do governo que já estão em andamento, e possibilitar o desenvolvimento econômico e social.

Recebido : 2/maio/2012; Aceito: 15/fev./2013 Resumo Este trabalho teve como objetivo comparar o desenvolvimento de cinco cultivares de soja produzidas no Estado de São Paulo, em situação de alagamento do sistema radicular, e avaliar a resposta das plantas ao nitrato nessa situação. No trabalho, foram analisadas a área foliar, a massa seca da parte aérea, o volume do sistema radicular e a massa seca do sistema radicular das cultivares de soja IAC Foscarin-31, IAC-23, IAC-17, IAC-24 e IAC-18, além de análise histológica do caule e da raiz principal da cultivar IAC-23, das plantas mantidas durante 28 dias alagadas. Todas as cultivares foram submetidas aos tratamentos: alagamento do vaso sem nitrato; alagamento com nitrato e alagamento com nitrato adicionado após sete dias de experimento. Os resultados indicam que a escolha da cultivar e a adição de nitrato devem ser levadas em consideração para o plantio em regiões com potencial para alagamento. A presença de nitrato foi benéfica para as cinco cultivares avaliadas. Na cultivar IAC-24 notou-se maior crescimento em presença de nitrato. A adição de nitrato sete dias após alagamento promoveu maior crescimento na cultivar IAC Foscarin-31. A presença de aerênquima no caule e na raiz principal de plantas alagadas foi constatada em todos os tratamentos, porém houve variação no arranjo das células parenquimáticas, o qual foi mais compacto nos tratamentos com nitrato.Palavras-chave: encharcamento, Glycine max, nitrogênio, crescimento vegetal. Nitrogen fertilization benefits soybean under flooding conditions AbstractThe aim of this study was to compare the growth of five cultivars of soybean produced in the State of São Paulo under conditions of flooding and evaluate the response of the plants to nitrate under such conditions. The study involved the analysis of leaf area, shoot dry mass, volume of the root system and root dry mass, using the soybean cultivars IAC Foscarin-31, IAC-23, IAC-17, IAC-24 and IAC-18, as well as a histological analysis of the stem and main root of the cultivar IAC-23, after being maintained for 28 days under flooding conditions. All cultivars were submitted to the following treatments: flooding of the root system without nitrate; flooding in the presence of nitrate; and flooding with nitrate added seven days after flooding. Our data indicate that the choice of cultivar and the use of nitrate should be taken into account for the planting of soybean in regions subject to flooding. The presence of nitrate during flooding was beneficial for all five cultivars tested. The cultivar IAC-24 presented the highest growth in the presence of nitrate. IAC Foscarin-31 was the most responsive cultivar to the addition of nitrate seven days after flooding, when considering plant growth. The presence of aerenchyma on the stem and main root of the flooded plants was observed for all treatments. However, variation occurred in the arrangement of parenchyma cells, this being more compact in the treatments with nitrate.

Waterlogging of soils is common in nature. The low availability of oxygen under these conditions leads to hypoxia of the root system impairing the development and productivity of the plant. The presence of nitrate under flooding conditions is regarded as being beneficial towards tolerance to this stress. However, it is not known how nodulated soybean plants, cultivated in the absence of nitrate and therefore not metabolically adapted to this compound, would respond to nitrate under root hypoxia in comparison with non-nodulated plants grown on nitrate. A study was conducted with 15 N labelled nitrate supplied on waterlogging for a period of 48 h using both nodulated and non-nodulated plants of different physiological ages. Enrichment of N was found in roots and leaves with incorporation of the isotope in amino acids, although to a much smaller degree under hypoxia than normoxia. This demonstrates that nitrate is taken up under hypoxic conditions and assimilated into amino acids, although to a much lesser extent than for normoxia. The similar response obtained with nodulated and non-nodulated plants indicates the rapid metabolic adaptation of nodulated plants to the presence of nitrate under hypoxia. Enrichment of N in nodules was very much weaker with a distinct enrichment pattern of amino acids (especially asparagine) suggesting that labelling arose from a tissue source external to the nodule rather than through assimilation in the nodule itself.

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