Busca avançada
Ano de início
Entree
Conteúdo relacionado
(Referência obtida automaticamente do Web of Science, por meio da informação sobre o financiamento pela FAPESP e o número do processo correspondente, incluída na publicação pelos autores.)

NITRATE REDUCTASE ACTIVITY AND SPAD READINGS IN LEAF TISSUES OF GUINEA GRASS SUBMITTED TO NITROGEN AND POTASSIUM RATES

Texto completo
Autor(es):
Lavres Junior, Jose [1] ; Gomes dos Santos, Jr., Joao de Deus [2] ; Monteiro, Francisco Antonio [3]
Número total de Autores: 3
Afiliação do(s) autor(es):
[1] Univ Sao Paulo, Lab Plant Nutr, Ctr Nucl Energy Agr CENA, BR-13400970 Piracicaba, SP - Brazil
[2] Embrapa Cerrados, BR-73310970 Planaltina, DF - Brazil
[3] ESALQ USP, Dept Soil Sci, Luiz de Queiroz Coll Agr, BR-13418900 Piracicaba, SP - Brazil
Número total de Afiliações: 3
Tipo de documento: Artigo Científico
Fonte: Revista Brasileira de Ciência do Solo; v. 34, n. 3, p. 801-809, MAY-JUN 2010.
Citações Web of Science: 13
Resumo

Nitrogen and K deficiency are among the most yield limiting factors in Brazilian pastures. The lack of these nutrients can hamper the chlorophyll biosynthesis and N content in plant tissues. A greenhouse experiment was carried out to evaluate the relationship among N and K concentrations, the indirect determination of chlorophyll content (SPAD readings), nitrate reductase activity (RNO(3)(-)) in newly expanded leaf lamina (NL) and the dry matter yield for plant tops of Mombaca grass (Panicum maximum Jacq.). A fractionated 5(2) factorial design was used, with 13 combinations of N and K rates in the nutrient solution. The experimental units were arranged in a randomized block design, with four replications. Plants were harvested twice. The first harvest occurred 36 days after seedling transplanting and the second 29 days after the first. Significance occurred for the interaction between the N and K rates to SPAD readings and to RNO(3)(-) assessment taken on the NL during the first growth. Besides, RNO(3)(-) and SPAD readings increased only with the NL N concentration, reaching the highest values of both variables up to about 25 g kg(-1), but were ratively constant at higher leaf N. Significant relationships either between SPAD readings or RNO(3)(-) activity and shoot dry mass weight were also observed. The critical levels of N concentration in the NL were, respectively, 22 and 17g kg(-1) in the first and second harvest. Thus, SPAD instrument and RNO(3)(-) assessment can be used as complementary tools to evaluate the N status in forage grass. (AU)

Processo FAPESP: 07/58406-1 - Avaliação da disponibilidade do níquel no solo por métodos químicos e biológico
Beneficiário:José Lavres Junior
Linha de fomento: Bolsas no Brasil - Pós-Doutorado