Nitrate reductase activity and spad readings in leaf tissues of guinea grass submitted to nitrogen and potassium rates.

LAVRES JUNIOR, J.; SANTOS JUNIOR, J. de D. G. dos; MONTEIRO, F. A.

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Campo DC	Valor	Lengua/Idioma
dc.contributor.author	LAVRES JUNIOR, J.	pt_BR
dc.contributor.author	SANTOS JUNIOR, J. de D. G. dos	pt_BR
dc.contributor.author	MONTEIRO, F. A.	pt_BR
dc.date.accessioned	2013-08-02T23:30:52Z	-
dc.date.available	2013-08-02T23:30:52Z	-
dc.date.created	2010-10-05	pt_BR
dc.date.issued	2010	pt_BR
dc.identifier.citation	Revista Brasileira de Ciência do Solo, v. 34, p. 801-809, 2010.	pt_BR
dc.identifier.uri	http://www.alice.cnptia.embrapa.br/alice/handle/doc/863616	pt_BR
dc.description	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 (RNO3 -) in newly expanded leaf lamina (NL) and the dry matter yield for plant tops of Mombaça grass (Panicum maximum Jacq.). A fractionated 52 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 RNO3 - assessment taken on the NL during the first growth. Besides, RNO3 - 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 RNO3 - 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 RNO3 assessment can be used as complementary tools to evaluate the N status in forage grass.	pt_BR
dc.language.iso	eng	eng
dc.rights	openAccess	eng
dc.subject	Guinea Grass	pt_BR
dc.subject	Pasture	pt_BR
dc.title	Nitrate reductase activity and spad readings in leaf tissues of guinea grass submitted to nitrogen and potassium rates.	pt_BR
dc.type	Artigo de periódico	pt_BR
dc.date.updated	2013-08-02T23:30:52Z	pt_BR
dc.subject.thesagro	Clorofila	pt_BR
dc.subject.thesagro	Estado Nutricional	pt_BR
dc.subject.thesagro	Gramínea Forrageira	pt_BR
dc.subject.nalthesaurus	chlorophyll	pt_BR
dc.subject.nalthesaurus	potassium	pt_BR
dc.subject.nalthesaurus	nitrogen	pt_BR
dc.subject.nalthesaurus	nutritional status	pt_BR
riaa.ainfo.id	863616	pt_BR
riaa.ainfo.lastupdate	2013-08-02	pt_BR
dc.contributor.institution	JOSÉ LAVRES JUNIOR, CENA/USP; JOÃO DE DEUS GOMES DOS SANTOS JUNIOR, CPAC; FRANCISCO ANTONIO MONTEIRO, ESALQ.	pt_BR
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