nÃo hà / Avaliou-se os efeitos de diferentes lÃminas de irrigaÃÃo e doses de nitrogÃnio (N) sobre as caracterÃsticas morfogÃnicas e estruturais, produÃÃo e composiÃÃo quÃmicobromatolÃgica
dos capins Andropogon gayanus cv. Planaltina e Brachiaria brizantha cv. Marandu. O estudo foi conduzido no perÃodo de agosto a dezembro de 2007, na Unidade de ExecuÃÃo de Pesquisa da EMBRAPA Meio-Norte, localizada no municÃpio
de ParnaÃba, PiauÃ. Os tratamentos consistiram em duas lÃminas de irrigaÃÃo (equivalente à reposiÃÃo de 50% e 80% da EvaporaÃÃo do Tanque Classe A - ECA) e quatro doses de nitrogÃnio (equivalente a 200, 400, 600 e 800 kg de N/ha x ano), em um delineamento em blocos casualizados, em esquema fatorial 2 x 4, com trÃs repetiÃÃes. As parcelas experimentais mediam 3 m x 8 m, sendo realizado um corte de
uniformizaÃÃo (agosto) e quatro cortes para coleta de dados a cada 30 dias, a 20 cm do solo. Em geral, nos capins estudados, a reduÃÃo da lÃmina de irrigaÃÃo, proporcionou
decrÃscimos nas taxas de alongamento da folha e do colmo, aparecimento de folha, comprimento final da folha e nÃmero de folhas vivas, enquanto que, taxa senescÃncia aumenta e duraÃÃo de vida de folhas à pouco afetada. A adubaÃÃo nitrogenada aumentou as taxas de alongamento da folha e do colmo, aparecimento de folha e comprimento final da folha. Contudo, tendeu a reduzir o nÃmero e a duraÃÃo de vida das
folhas, e a ampliar a taxa senescÃncia. As lÃminas aplicadas apresentaram comportamentos semelhantes em relaÃÃo à produtividade de matÃria seca total e de folhas. Todavia, a lÃmina de 80% de ECA proporcionou as maiores alturas de plantas e menor relaÃÃo folha/colmo. A maior lÃmina de irrigaÃÃo promoveu aumentos da produÃÃo de colmo, porÃm nÃo afetou a produÃÃo de folhas. Em geral a adubaÃÃo
nitrogenada influenciou positivamente a produtividade de matÃria seca total, de folhas e colmos, mas, diminuiu a eficiÃncia de utilizaÃÃo do nitrogÃnio e relaÃÃo folha/colmo. As
lÃminas de irrigaÃÃo nÃo afetaram os teores de matÃria seca (MS) das folhas do capimandropogon. A maior lÃmina de irrigaÃÃo promoveu reduÃÃo expressiva dos teores de MS da folha do capim-marandu e colmo das duas gramÃneas. A adubaÃÃo nitrogenada nÃo afetou os teores de MS do capim-andropogon. No entanto, nas folhas do capimmarandu os teores de MS decresceram inversamente proporcional aos nÃveis de nitrogÃnio aplicado. Os teores de proteÃna das duas gramÃneas nÃo foram influenciados pelas lÃminas de irrigaÃÃo. A adubaÃÃo nitrogenada aumentou linearmente os teores de proteÃna das folhas e dos colmos. A utilizaÃÃo da maior lÃmina promoveu incrementos nos teores de FDN dos capins estudados. Os teores de FDN foram inversamente proporcionais aos nÃveis de adubaÃÃo. Os teores de FDA sofreram influÃncia negativa da maior lÃmina de irrigaÃÃo. Os nÃveis de adubaÃÃo nitrogenada promoveram decrÃscimos nos nÃveis de FDA. Em geral, a adubaÃÃo nitrogenada promoveu melhoria no valor nutritivo do capim-marandu. / The objective of this work was to evaluate the effects of different irrigation and doses of
nitrogen on the morphogenetic and structural characteristics, forage production and
bromatologic composition of
Andropogon gayanus
var. Planaltina and
Brachiaria
brizantha
var. Marandu. The study was conducted from August to December 2007 on
Unit Research of EMBRAPA Meio-Norte, located in city of ParnaÃba, PiauÃ, Brazil. The
treatments consisted of two irrigation levels (with a equivalent level to replacement of
50% and 80% of evaporation of the Class A pan - ECA) and four doses of nitrogen
(equivalent to 200, 400, 600 and 800 N/ha x year), in a completely randomized block
design in a 2 x 4 factorial design with three replications. The plots measuring 3 m x 8
m, and made a cut of uniformity (in August) and four cuts to collect data every 30 days,
at 20 cm the soil. In general, in grass Andropogon and Marandu, the reduction of the
irrigation level, provides decreases in leaf elongation and stem elongation rate, leaf
appearance and final leaf length, whereas, leaf senescence rate increases and duration of
life of leaf little is affected. Leaf senescence rate of grass tended to increase ahead of the
lesser water availability of the ground. The nitrogen fertilization increases the rates of
elongation e leaf and stem, leaf appearance and final length of the leaf. However, it
tends to reduce the number it and the duration of life of the leaf, and to extend rate
senescence. The applied irrigation levels presented similar behaviors in relationship of
productivity of total dry matter and of leaves. Though the level of 80% of ECA
provided the largest heights of plants and smaller relation leaf/stem ratio. The largest
irrigation level promoted increases of the production of stem, even so it didn't affect the
production of leaves. In general the nitrogen fertilization influenced the productivity of
total dry matter positively, of leaves and stem, however, it decreased the efficiency of
use of the nitrogen and relation leaf/stem ratio. Increasing doses of nitrogen reduces the
dry matter at the same time as the irrigation level of 80% decreasing these values, both
for the leaf and to stem fraction. The irrigation level of 80% decreases the crude protein
18
contents, both for the leaf and to stem at the same time it increases the levels of ADF
both for the leaf and to stem. The irrigation levels didn't affect the content of dry matter
of the Andropogon grass. The largest irrigation level (80% of ECA) it promoted
expressive reduction of the level of DM of the leaf of the Marandu grass and the stem of
both grasses. The fertilization nitrogen didn't affect the texts of DM of the Andropogon
grass. Though, in the leaves of the Marandu grass the content of DM decreased
inversely in way proportional at the levels of applied nitrogen. The contents protein of
the researched grasses was not influenced by the applied irrigation levels. The
fertilization nitrogen increased the contents of protein of the leaves lineally and stems,
and the largest texts were obtained with the applications of 600 and 800 kg the N/ha x
year. The interaction fertilization nitrogen x irrigation levels increased the contents of
NDF of the leaves of the Andropogon grass. The use of the largest level (80% of ECA)
it promoted increments in the contents of NDF of the studied grasses. Though, the
contents of NDF went inversely proportional at the fertilization levels. The contents of
ADF suffered it influences negative of the largest irrigation level. The doses of
fertilization nitrogen promoted decreases in the levels of FDA. In general, the
fertilization nitrogen improvement in the nutritious value of Marandu grass
| Identifer | oai:union.ndltd.org:IBICT/oai:www.teses.ufc.br:4331 |
| Date | 26 March 2010 |
| Creators | JoÃo Avelar MagalhÃes |
| Contributors | Maria Socorro de Souza Carneiro, Alex Carvalho Andrade, ElzÃnia Sales Pereira, AlberÃcio Pereira de Andrade, Olaf Andreas Bakke |
| Publisher | Universidade Federal do CearÃ, Programa de PÃs-GraduaÃÃo Integrado em Zootecnia-PDIZ, UFC, BR |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | application/pdf |
| Source | reponame:Biblioteca Digital de Teses e Dissertações da UFC, instname:Universidade Federal do Ceará, instacron:UFC |
| Rights | info:eu-repo/semantics/openAccess |
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