This study evaluated the antibacterial and antiproliferative activities of the essential oil of Psidium guajava leaves (PG-EO), traditionally used in folk medicine. The essential oil was obtained from fresh leaves by hydrodistillation, using a modified Clevenger apparatus. The major PG-EO chemical constituents were identified by GC-MS and GC-FID as being β-caryophyllene (16.1%), α-humulene (11.9%), aromadendrene oxide (14.7%), δ-selinene (13.6%), and selin-11-en-4α-ol (12.5%). The antibacterial activity of the essential oil of P. guajava leaves was determined in terms of its minimum inhibitory concentrations (MIC) using the broth microdilution method in 96-well microplates. PG-EO had moderate activity against Streptococcus mutans (MIC = 200 µg/mL), S. mitis (MIC = 200 µg/mL), S. sanguinis (MIC = 400 µg/mL), S. sobrinus (MIC = 100 µg/mL), and S. salivarius (MIC = 200 µg/mL). The antiproliferative activity was evaluated against different tumor cell lines: breast adenocarcinoma (MCF-7), human cervical adenocarcinoma (HeLa), and human gliobastoma (M059J). A normal human cell line (GM07492A, lung fibroblasts) was included. The antiproliferative activity was evaluated using the XTT assay and the results were expressed as IC50. The essential oil showed significantly lower IC50 values against MCF-7 and M059J lines than that obtained for the normal line, showing selectivity. Our results suggest that the essential oil of Psidium guajava L. has promising biological activities and can be considered a new source of bioactive compounds.

Globally, the fungus Sclerotinia sclerotiorum is considered as one of the most important phytopathogens, since it affects the production of several economically important crops. Further, it is difficult to control, thus increasing the use of pesticides. Therefore, the search for new substances, especially those extracted from plants, has received special attention to control this plant pathogen. The objective of the present study was to evaluate the yield and chemical composition of the essential oil extracted from the fresh leaves of guava collected during the rainy and dry seasons, and also to evaluate its toxicity against S. sclerotiorum. The experiment was a completely randomized design with five treatments and six replicates. The essential oil was extracted by hydrodistillation of the leaves and analyzed by gas chromatography-flame ionization detector and gas chromatography-mass spectrometry. The main compounds identified in the essential oil were trans-caryophyllene and ?-humulene. The essential oil at a concentration of 300 ?L exhibited 90% inhibition of the mycelial growth of S. sclerotiorum. This confirmed the antifungal potential of the essential oil of the guava leaves during both the sampling seasons.

The cultivation of soybean in Brazil experienced an expressive growth in the last decades. Soybean is highly demanding on nitrogen (N) that must come from fertilizers or from biological fixation. The N supply to the soybean crop in Brazil relies on the inoculation with elite strains of Bradyrhizobium japonicum, B. elkanii, and B. diazoefficiens, which are able to fulfill the crop's N requirements and enrich the soil for the following crop. The effectiveness of the association between N2-fixing bacteria and soybean plants depends on the efficacy of the inoculation process. Seed treatment with pesticides, especially fungicides or micronutrients, may rapidly kill the inoculated bacteria, affecting the establishment and outcome of the symbiosis. The development of technologies that allow inoculation to become a successful component of industrial seed treatment represents a valuable tool for the seed industry, as well as for the soybean crop worldwide. In this article, we report the results of new technologies, developed by the company Total Biotecnologia Indústria e Comércio S/A of Brazil, for preinoculation of soybean seeds with bradyrhizobia, in the presence of agrichemicals. Our results demonstrate improved bacterial survival for up to 30 days after inoculation, without compromising nodulation, N2-fixation, and yield in the field.

ResumoO presente trabalho objetivou comparar o comportamento da cultura da soja adubada com fósforo e potássio em semeadura e a lanço antecipada. Para isso foi realizado um experimento em Latossolo Vermelho distroférrico. O delineamento experimental utilizado foi em blocos ao acaso com 6 tratamentos e 4 repetições. Os tratamentos experimentais foram: 1) ausência de adubação; 2) P e K na semeadura; 3) P e K antecipada; 4) P antecipado e K na semeadura; 5) K antecipado e P na semeadura; 6) metade de P e K antecipada e a outra metade em semeadura. As variáveis analisadas foram: produtividade, número de grãos por vagem, número de vagens por planta e peso de 1000 grãos. Nas condições estudadas, não houve diferença entre a adubação fosfatada e potássica em semeadura e a lanço antecipada para a cultura da soja. Assim, sugere-se optar por aquela forma de aplicação de fertilizante que garanta o menor custo. Palavras-chave: Glycine max, adubação antecipada, fertilizantes, fertilidade do solo AbstractThis work aimed to compare the soybean yield when phosphorus and potassium manuring was anticipated or at sowing. The experiment was carried out under field conditions in a dystrophic Red Latosol (Oxisol). A completely randomized block design with six treatments and four replicates was used. The treatments were: 1) no manuring; 2) P and K at sowing; 3) anticipated P and K; 4) anticipated P; 5) anticipated K; 6) half of P and K anticipated and the another half at sowing. Yield, weight of 1000 grains, number of grains per pods and number of pods per plant were evaluated at harvest. There was no difference between anticipated and sowing fertilization to soybean. Therefore, the best option to soil fertilization should be that with the lowest cost.

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