DSpace Communidade: Embrapa Amazônia Ocidental (CPAA)

Urochloa brizantha and Amazonian Dark Earths reshape soil microbiota without affecting tree growth in degraded Central Amazon Oxisols.

2026-05-23T12:51:08Z

Título: Urochloa brizantha and Amazonian Dark Earths reshape soil microbiota without affecting tree growth in degraded Central Amazon Oxisols. Autoria: FREITAS, A. S. de; HANADA, R. E.; MUNIZ, A. W.; TSAI, S. M. Conteúdo: Amazonian Dark Earths (ADE) are fertile anthropogenic soils rich in organic matter and microbial diversity, offering potential for restoring degraded tropical soils. We tested the combined effects of ADE (2% w/w) and Urochloa brizantha conditioned soil (CS 20%) on soil microbial communities and early growth of four tree species (Cecropia pachystachya, Schizolobium amazonicum, Handroanthus avellanedae, Acacia mangium) in a pasture-degraded Oxisol. Plant performance, soil enzyme activity, prokaryotic community structure (16S rRNA sequencing), predicted functions, and co-occurrence networks were evaluated. Neither ADE nor U. brizantha, alone or combined, significantly improved tree growth or microbial alpha diversity (p < 0.05). However, the combination CS+ADE shifted microbial composition, reducing by 3-fold the abundance of several aerobic Gram-positive taxa (Actinophytocola, Lysinibacillus, Rubrobacter) and nitrogen-fixers (Herbaspirillum). Network analyses showed treatment-specific connectivity changes, especially in Cecropia and Acacia, where CS+ADE increased both positive and negative microbial associations. Functional prediction and enzyme assays revealed a largely stable functional core, except for a 70% decline in β-glucosidase activity in Acacia under CS+ADE, indicating altered carbon cycling. Overall, while microbial networks responded strongly, limited ADE input and the stability of native microbiota constrained plant and functional benefits, underscoring the importance of application strategies in restoration.

Addition of Lippia sidoides essential oil to tilapia diet: performance analysis, blood parameters, and challenges of air exposure and experimental infection.

2026-05-17T22:09:27Z

Título: Addition of Lippia sidoides essential oil to tilapia diet: performance analysis, blood parameters, and challenges of air exposure and experimental infection. Autoria: ANDRADE, J. I. A. de; FERREIRA, G. B.; KOPITSKI, P.; SILVA, E. da; MARTINS, M. L.; CHAVES, F. C. M.; MENDES, R. E.; JATOBÁ, A. Conteúdo: This study evaluated the effects of Lippia sidoides essential oil (LSEO) as a growth and health promoter for juvenile tilapia subjected to stress induced by air exposure and experimental infection with Aeromonas hydrophila. Juvenile were allocated to 15 tanks (in triplicate) and fed diets containing 0.0% (Control), 0.05%, 0.1%, 0.2%, or 0.4% LSEO for 33 days. For the air exposure challenge, five fish from each tank were exposed to air for five minutes after the feeding period. Blood samples were collected for hematological analysis. For the infection challenge, six fish from each tank were intraperitoneally inoculated with 100 µL of A. hydrophila and monitored for ten days. Hematological and histomorphometric parameters were assessed. The results indicated that the 0.4% LSEO supplementation reduced feed conversion ratios (P < 0.05). Before the challenges, LSEO concentrations influenced total counts of neutrophils, basophils, and monocytes (P < 0.05). After the air exposure and infection challenges, no significant differences were observed among treatments for these parameters (P > 0.05). Regarding hematimetric indices, all parameters were affected by LSEO concentrations prior to the challenges (P < 0.05). Although LSEO supplementation improved feed conversion, it did not mitigate the hematological alterations caused by the stress challenges.

Efeito do volume do tanque-rede na produtividade de tambaqui (Colossoma macropomum) durante a recria.

2026-05-09T15:18:50Z

Título: Efeito do volume do tanque-rede na produtividade de tambaqui (Colossoma macropomum) durante a recria. Autoria: GOMES, L. de C.; BRANDÃO, F. R.; CHAGAS, E. C.; FERREIRA, M. F. B.; LOURENCO, J. N. de P. Conteúdo: O objetivo deste trabalho foi avaliar o efeito do volume do tanque-rede na produtividade de juvenis de tambaqui durante a recria. Juvenis de tambaqui foram criados por 60 dias, na densidade de 300 peixes/m3, em tanques-rede de dois diferentes volumes: 1 e 6 m3. Foram avaliados parâmetros de crescimento e de produtividade final.

Densidade de estocagem de juvenis de tambaqui durante a recria em tanques-rede.

2026-05-09T15:18:30Z

Título: Densidade de estocagem de juvenis de tambaqui durante a recria em tanques-rede. Autoria: BRANDÃO, F. R.; GOMES, L. de C.; CHAGAS, E. C.; ARAÚJO, L. D. de Conteúdo: O objetivo deste trabalho foi determinar a densidade de estocagem mais adequada para a fase de recria de tambaqui em tanque-rede. Foram utilizados 12 tanques-rede de 1m3 cada, onde os peixes foram distribuídos em quatro densidades (três repetições): 200, 300, 400 e 500 peixes m-3. Os peixes foram alimentados seis vezes por semana em três refeições diárias com ração comercial com 36% de proteína bruta, durante 60 dias. Foi analisado o crescimento em peso, comprimento, o coeficiente de variação do comprimento, a taxa de crescimento específico e a glicose sanguínea nos dias 30 e 60 de criação. Ao final do experimento, foram analisados os seguintes parâmetros de produtividade final: sobrevivência, conversão alimentar aparente, ganho de peso e produção por área.