Atividade da redutase do nitrato em cana-de-açúcar
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Data
2013-12-18
Autores
Santos, Carlos Leandro Rodrigues dos [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Na primeira fase do estudo realizou-se, para cana-de-açúcar, a padronização das condições de determinação da atividade da enzima redutase do nitrato (RN). Além disso, procedeu-se um estudo para a caracterização da sua atividade em plantas da cultura. Na segunda etapa, acompanhou-se, ao decorrer do tempo após a aplicação de N, a variação dos níveis de atividade da RN em plantas de cana-de-açúcar deficientes do nutriente. Observou-se que a atividade da enzima é máxima aos 13 dias após a aplicação e que plantas deficientes em N, independente da fonte nitrogenada usada, apresentam o mesmo comportamento, e ainda, que a resposta enzimática é mais rápida com a aplicação de nitrato de amônio em relação à uréia ou sulfato de amônio. Na terceira fase, comparou-se cultivares de cana-de-açúcar quanto ao nível de atividade da RN e verificou-se sua relação com variáveis produtivas e nutricionais, tanto em condições controladas como no campo. Observou-se que a atividade da RN varia com a cultivar e que existe relação entre a atividade da enzima e o teor de N, e ainda, que teores de nitrato foliar não se associam com a atividade da enzima. Na última fase da pesquisa, estudou-se o efeito da dose de N na atividade da enzima RN. Os resultados sugeriram que em plantas com severa deficiência de N, a atividade da RN é influenciada pela dose. Constatou-se que, devido aos baixos teores de nitrato foliar, não há atividade da RN sem a adição de nitrato no meio reacional e que, a atividade da enzima apresenta boas perspectivas para indicar a nutrição nitrogenada de plantas de cana-de-açúcar, porém, ainda existe a necessidade do estabelecimento de um critério para o diagnóstico
In the first phase of the study was held, for sugarcane, the standardization of the conditions for determining the nitrate reductase activity (NR). Furthermore, a study was conducted for characterization of its activity in crop plants. In the second step, we accompanied, over time after N application, the variation in levels of NR activity in sugarcane plant N deficient. It was observed that the enzyme activity is maximal after 13 days of application and in plants deficient in N, independent of the N source used, plants show the same behavior, and that the enzymatic response is faster with the application of ammonium nitrate than urea or ammonium sulfate. In the third phase, we compared sugarcane cultivars in the level of NR activity and was verified its relationship with productive and nutritional variables, under controlled conditions and field. It was observed that NR activity varies with the cultivar and that there is a relationship between the enzyme activity and N content. Also, that the nitrate foliar was not associated with the enzyme activity. In the last phase of the research, we studied the effect of N application in enzyme NR activity. The results suggested that in plants with severe deficiency of N, NR activity is influenced by rate. It was found that due to the low levels of nitrate in the leaf does not occur increase of RN activity without the addition of nitrate in the reaction medium and that enzyme activity shows goods perspectives for indicate nitrogen nutrition of sugarcane plants, however, there is necessity of the establishment of a criterion for the diagnostic
In the first phase of the study was held, for sugarcane, the standardization of the conditions for determining the nitrate reductase activity (NR). Furthermore, a study was conducted for characterization of its activity in crop plants. In the second step, we accompanied, over time after N application, the variation in levels of NR activity in sugarcane plant N deficient. It was observed that the enzyme activity is maximal after 13 days of application and in plants deficient in N, independent of the N source used, plants show the same behavior, and that the enzymatic response is faster with the application of ammonium nitrate than urea or ammonium sulfate. In the third phase, we compared sugarcane cultivars in the level of NR activity and was verified its relationship with productive and nutritional variables, under controlled conditions and field. It was observed that NR activity varies with the cultivar and that there is a relationship between the enzyme activity and N content. Also, that the nitrate foliar was not associated with the enzyme activity. In the last phase of the research, we studied the effect of N application in enzyme NR activity. The results suggested that in plants with severe deficiency of N, NR activity is influenced by rate. It was found that due to the low levels of nitrate in the leaf does not occur increase of RN activity without the addition of nitrate in the reaction medium and that enzyme activity shows goods perspectives for indicate nitrogen nutrition of sugarcane plants, however, there is necessity of the establishment of a criterion for the diagnostic
Descrição
Palavras-chave
Cana-de-açúcar - Adubação, Cana-de-açúcar - Nutrição, Fertilizantes nitrogenados, Enzimas, Nitrogenio - Metabolismo, Nitrogen in agriculture
Como citar
SANTOS, Carlos Leandro Rodrigues dos. Atividade da redutase do nitrato em cana-de-açúcar. 2013. iv, 187 p. Tese (doutorado) - Universidade Estadual Paulista, Faculdade de Ciências Agrárias e Veterinárias de Jaboticabal, 2013.