Phosphorus (P) deficiency is a major constraint in highly weathered tropical soils. Although phosphorous rock reserves may last for several hundred years, there exists an urgent need to research efficient P management for sustainable agriculture. Plant hormones play an important role in regulating plant growth, development, and reproduction. Humic substances (HS) are not only considered an essential component of soil organic carbon (SOC), but also well known as a biostimulant which can perform phytohormone-like activities to induce nutrient uptake. This review paper presents an overview of the scientific outputs in the relationship between HS and plant hormones. Special attention will be paid to the interaction between HS and plant hormones for nutrient uptake under P-deficient conditions.

Seed germination events modulate microbial community composition, which ultimately influences seed-to-seedling growth performance. Here, we evaluate the germinated maize (variety SHS 5050) root bacterial community of disinfected seed (DS) and non-disinfected seed (NDS). Using a gnotobiotic system, sodium hypochlorite (1.25%; 30 min)-treated seeds showed a reduction of bacterial population size and an apparent increase of bacterial community diversity associated with a significant selective reduction of Burkholderia-related sequences. The shift in the bacterial community composition in DS negatively affects germination speed, seedling growth and reserve mobilization rates compared with NDS. A synthetic bacterial community (syncom) formed by 12 isolates (9 Burkholderia spp., 2 Bacillus spp., and 1 Staphylococcus sp.) obtained from natural microbiota maize seeds herein was capable of recovering germination and seedling growth when reintroduced in DS. Overall, results showed that changes in bacterial community composition and selective reduction of Burkholderia-related members' dominance interfere with germination events and the initial growth of the maize. By cultivation-dependent and -independent approaches, we deciphered seed–maize microbiome structure, bacterial niches location and bacterial taxa with relevant roles in seedling growth performance. A causal relationship between seed microbial community succession and germination performance opens opportunities in seed technologies to build-up microbial communities to boost plant growth and health.

Effective microorganisms (EM) are inoculants formed by fungi and bacteria isolated from soil. EM are commonly used by farmers on agronomic crops to stimulate plant growth, but their composition and their benefits has been controverted. This study aimed to analyze the diversity of microorganisms growing in three EM inoculants, as well as to evaluate their efficiency in the germination of palisade grass seeds. The total DNA of the three EM inoculants was extracted, the 16S rRNA and ITS genes were amplified by PCR and sequenced on the Illumina MiSeq platform. Germination tests were conducted with three type of the EM, in three concentration and two times of the immersion. The bacterial group was the most abundant in EM, followed by fungi. Bacterial operational taxonomic units OTUs were shared by all EMs. Pre-treatments of palisade grass seeds with EMs resulted in a higher germination percentage (% G) and germination speed index (IVG) when EM was used at concentration of 1 or 2% in water. Seed immersion for 5 min was more efficient than immersion for 24 h. We can conclude that EM of different origin can share microbial groups and diversity of microorganisms, besides being an alternative to increase palisade grass seeds germination.

Effective microorganisms (EM) are inoculants used by farmers on various crops, and the actual efficiency of EM and their composition have been widely discussed. The objective of this study was to analyze the profile of the microbial community in soils after applying 3 EM inoculants from different origins with and without manure and to determine the impacts on growth and chemical composition of Urochloa brizantha (palisade grass). We showed, by PCR-DGGE technique, that the community structure of the fungi and bacteria in soil differed with EMs from different sources and that adding manure to the soil also significantly altered the bacterial and fungal profile. We also found that adding manure to soil resulted in a pronounced increase in both dry matter yield and crude protein concentration in palisade grass, while benefits of applying EM were largely restricted to a farmer-produced inoculant, where CP% was increased and NDF% was reduced when applied along with manure.

O ensino de Ciências e Biologia torna o cidadão mais crítico acerca dos fenômenos naturais que os cercam, assim, é importante criar práticas pedagógicas que ensinem essas disciplinas de forma lúdica, unindo teoria e prática. No entanto, as escolas públicas não apresentam uma estrutura laboratorial que atenda a essa demanda. Assim, surge a necessidade dos professores adotarem práticas alternativas. Dentre essas práticas tem-se a implantação de hortas na escola, alternativa que tem se mostrado eficiente no processo de ensino-aprendizagem.