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2008- Elias Melo de Miranda.pdf: 858590 bytes, checksum: fe12f644fd0dbcad694f77bd0dea494b (MD5)
Previous issue date: 2008-02-21 === This study was conducted at Embrapa Agrobiologia experimental area, in Serop?dica
municipality, Rio de Janeiro State, with the objective of evaluating the association of
arbuscular mycorrhizal fungi (AMF) with the foraging peanut (Arachis pintoi) in four
situations of cultivation. The first study examined the association of peanuts with
autochthonous AMF, from soil samples collected in Rio Branco municipality state of Acre,
in areas of this legume as a single crop, and intercropped with pasture and coffee, as well as in
secondary and primary forest. The AMF species were identified, determined the spore density
and the root colonization rates, and then calculated the indexes of diversity. The other
experiments were performed under greenhouse conditions, assessing the peanut seedlings
response to inoculation with AMF species. The second study aimed to select the AMF
effective in promoting growth of seedlings originating from seeds, and rooting of stolons in
polystyrene trays, in substrate of low fertility, without additional fertilizer. In the third, it was
investigated the response of seedlings propagated by rooting of stolons in condition of
increasing doses of phosphorus. In the fourth study, the goal was to select AMF species that
could improve the peanut forage performance cultivated in consortium with Brachiaria
decumbens. The AMF species used were: Glomus etunicatum, Glomus clarum, Gigaspora
margarita, Scutellospora heterogama, Acaulospora morrowiae and Entrophospora
colombiana. It was assessed, among other variables, the dry matter production of shoots and
roots. The analysis of the autochthonous community of AMF in agrosystems with A. Pintoi,
notably in the monocrop system, indicated that this legume was a good host of AMF species,
being useful to increase the density of spores and diversity of these organisms in the
agrosystems. The analysis of the AMF community in the pastures intercropped with A. pintoi
showed that this legume helped to increase the density of spores and diversity of species of
AMF in the agrosystems. AMF species of greatest efficiency in promoting growth and
nutrition of seedlings of A. Pintoi originated from seeds were E. colombiana, G. margarita,
G. clarum, and A. morrowiae. However, for the seedlings originated of the rooting of stolons
in polystyrene trays and without additional fertilization, it was not possible to detect a benefit
of the mycorrhization. Though, these seedlings responded to the phosphate fertilization, and
the response was most pronounced when inoculated with efficient AMF. In the intercropped
cultivation, the treatments of inoculation were beneficial for both plant components of the
system, and the A. Pintoi plants colonized by G. Clarum were most efficient to compete with
the brachiaria grass. === Este trabalho foi realizado na ?rea experiemntal da Embrapa Agrobiologia em Serop?dica -
RJ, com o objetivo de avaliar a associa??o de fungos micorr?zicos arbusculares (FMAs) com o
amendoim forrageiro (Arachis pintoi) em quatro situa??es de cultivo. O primeiro estudo
avaliou a associa??o do A. pintoi com FMAs aut?ctones, a partir de amostras de solo coletado
em Rio Branco, AC, em ?reas de monocultivo e de cons?rcio desta leguminosa com
gram?neas e cafeeiro, assim como em ?reas de capoeira e mata. As esp?cies de FMAs foram
identificadas, determinada a densidade de esporos e as taxas de coloniza??o radicular e, ent?o,
calculados ?ndices de diversidade. Os demais ensaios foram realizados em condi??es de casade-
vegeta??o, avaliando-se a resposta das mudas de amendoim ? inocula??o com esp?cies de
FMAs. O segundo estudo teve o objetivo de selecionar os FMAs mais eficientes em promover
o crescimento de mudas originadas de sementes e do enraizamento de estol?es em bandejas
de isopor, em substrato de baixa fertilidade natural, sem aduba??o suplementar. No terceiro,
foi investigada a resposta de mudas propagadas por enraizamento de estol?es a doses
crescentes de f?sforo. No quarto estudo, o objetivo foi selecionar esp?cies de FMAs que
melhorassem o desempenho do amendoim forrageiro na condi??o de cons?rcio com
Brachiaria decumbens. As esp?cies de FMAs estudadas foram: Glomus etunicatum, Glomus
clarum, Gigaspora margarita, Scutellospora heterogama, Acaulospora morrowiae e
Entrophospora colombiana, sendo avaliada, entre outras vari?veis, a produ??o de mat?ria
seca da parte a?rea e de ra?zes. A an?lise da comunidade de FMAs aut?ctones nos
agrossistemas com A. pintoi, notadamente em seu monocultivo, mostrou que esta leguminosa
foi uma boa hospedeira de esp?cies de FMAs, contribuindo para aumentar a densidade de
esporos e a diversidade destes organismos nos agrossistemas. As esp?cies de FMA de maior
efici?ncia em promover o crescimento e nutri??o de mudas de A. pintoi originadas de
sementes foram E. colombiana, G. margarita, G. clarum e A. morrowiae. Por?m, nas mudas
originadas do enraizamento de estol?es, nas bandejas de isopor e sem fertiliza??o
suplementar, n?o foi poss?vel detectar benef?cio da micorriza??o. Entretanto, estas mudas
responderam ? fertiliza??o fosfatada, sendo esta resposta mais acentuada quando foram
micorrizadas com FMAs eficientes. No cultivo consorciado, os tratamentos de inocula??o
foram ben?ficos para ambas as plantas do sistema e as plantas de A. pintoi colonizadas por G.
clarum foram mais eficientes em competir com a braqui?ria.
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