DSpace Coleção: Artigo em periódico indexado (CPAA)

Mechanical damage in soybeans by pneumatic seeder.

2026-06-08T15:48:38Z

Título: Mechanical damage in soybeans by pneumatic seeder. Autoria: MEDEIROS, F. A.; WESTENDORFF, N. da R.; TUNES, L. V. M. de; REIS, A. V. dos; MUNIZ, A. W.; MENEGELLO, G. E. Conteúdo: Research has advanced in the development of precision seed metering devices to ensure proper seed distribution at high speeds. However, little is known about the effect of increasing seeding speed, as well as seeding at different inclinations of the tractor-seeder unit, on the integrity and physiological quality of soybean seeds. This study aimed to identify the effect of travel speeds (5, 7, 9, 11, and 13 km h−1) combined with three longitudinal inclinations of a pneumatic seed metering device (−11◦, 0◦, and 11◦), simulating field conditions, on the distribution and integrity of soybean seeds. We used a 5 × 3 factorial design was used with an additional control treatment in which the seeds did not pass through the metering device. The variables evaluated included the percentage of spacing between individual seeds, germination, mechanical damage (tetrazolium test), and seedling emergence. The results demonstrated that increasing the speed did not prevent the spacing between individual seeds from falling below the minimum limit of 90% for pneumatic seed metering devices. The treatments did not affect germination compared to the control. Sowing on a slope caused the greatest mechanical damage to soybean seeds. All treatments significantly reduced plant emergence, except when the pneumatic metering device operated at an incline of 0◦ at 9 km h−1.

Clonal propagation of segregating genotypes through somatic embryogenesis from zygotic embryos in an interspecific oil palm backcross.

2026-06-08T14:48:42Z

Título: Clonal propagation of segregating genotypes through somatic embryogenesis from zygotic embryos in an interspecific oil palm backcross. Autoria: BALZON, T. A.; MONTEIRO, T. R.; LOPES, R.; CUNHA, R. N. V. da; GOMES, H. T.; SILVA-CARDOSO, I. M. de A.; SOUZA, A. L. X. de; INGLIS, P. W.; PEREIRA, J. E. S. Conteúdo: Oil palm breeding programs are constrained by the reliance on sexual propagation, in which each seedling represents a unique genotype. This intrinsic genetic variability prevents the replicated evaluation of segregating genotypes across genetically comparable individuals and increases the risk of false-positive selection driven by environmental variance. In this study, we investigated whether somatic embryogenesis from zygotic embryos of an interspecific oil palm backcross (Elaeis oleifera × Elaeis guineensis) x E. guineensis could enable the production of multiple plants from a single zygotic embryo, allowing the evaluation of segregating genotypes across genetically similar individuals while maintaining genetic stability. A total of 198 zygotic embryos obtained from mature seeds of a single backcross genotype (SQ 150) were used as explants for somatic embryogenesis induction and plant regeneration. Molecular analyses were performed on 36 regenerated plants derived from three independent donor embryos using ISSR and methylation-sensitive AFLP (MSAP) markers. Differences among classes were assessed using a chi-square (χ²) test and considered significant at p < 0.05. ISSR analysis revealed high genetic similarity (97.5–100%) among regenerants derived from the same donor embryo, indicating strong intra-line genetic stability. In contrast, comparisons among regenerants originating from different donor embryos showed approximately 80% similarity, reflecting the expected genetic variability among zygotic embryos. MSAP analysis identified 357 loci, of which 69% were sensitive to DNA methylation. Epigenetic variation was mainly associated with fragment gain events (58%), indicating a predominance of genomic hypomethylation during regeneration. These results demonstrate that somatic embryogenesis from zygotic embryos can generate genetically consistent regenerants within embryogenic lines while maintaining epigenetic plasticity. This approach enables the production of multiple plants from a single zygotic embryo and supports the evaluation of segregating genotypes across genetically similar individuals, potentially improving selection accuracy in oil palm breeding programs.

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.