The identification of stress conditions in soybean crops is, in most cases, inaccurate, since they may not be noticeable to their full extent if only walking observations are carried out in the crop fields. This study aimed to identify the stress conditions in soybean crops, in three growing environments, in the Minas Gerais state, Brazil, using image processing techniques obtained by UAV, leaf and soil sensors, and climate data. The surveys encompassed two growth stages [beginning of blooming (R1) and beginning of seed enlargement (R5)] and consisted on UAV flights; mapping of chlorophyll content, soil moisture and soil pH; in addition to climate data. The HSV and yCbCr color models applied to RGB images showed the best Kappa accuracy index for the identification of crop features. The soil pH and moisture (water availability), solar radiation and temperature affected the crop growth and development in the study regions, in the R1 and R5 reproductive stages. However, the soil pH had less influence than the climatic variables. The R5 stage showed a greater vulnerability to stress caused by soil moisture and temperature.

O aumento das concentrações de elementos-traços no solo pode ocorrer tanto em razão de atividades antropogênicas quanto por processos naturais. O objetivo deste trabalho foi investigar a concentração natural de chumbo (Pb) nos solos de Minas Gerais em comparação aos valores orientadores preconizados na Resolução CONAMA nº 420 de 2009. Este trabalho pode ser utilizado para o gerenciamento do metal no Estado de Minas e informar a população em geral os riscos prováveis que estão subordinadas. Para subsidiar este trabalho foram utilizados o Mapa de Solos de Minas Gerais e o Mapa Geológico de MG. Em Minas Gerais há maior ocorrência de áreas não antropizadas com concentração de Pb abaixo do VRQ; e apenas seis áreas apresentaram potencial de contaminação natural, justificadas pela geologia e pela classe de solo de cada região.

Lead acetate (AcPb) is an important raw material used in chemical industries worldwide. The potential toxicity of AcPb is generally attributed to the presence of Pb. However, the effect of AcPb on the environment as a whole is still poorly known. This study aimed to evaluate AcPb toxicity on three standard species of soil invertebrates and two plant species using ecotoxicology tests. Three tropical soils (Oxisol, Inceptisol, and Tropical Arti cial Soil (TAS)) were contaminated with different concentrations of AcPb and one dose of K-acetate (positive control). These soils were used in tests with Eisenia andrei (earthworm), Folsomia candida (springtail), Enchytraeus crypticus (enchytraeid), Zea mays (maize), and Phaseolus vulgaris (common bean). Dose-response curves obtained in the laboratory tests were used to estimate the EC 50 values for each species. Among invertebrates, the highest sensitivity to AcPb was observed for E. crypticus in the TAS (EC 50 = 29.8 mg AcPb kg − 1 ), whereas for E. andrei and F. candida the highest sensitivity was observed in the Oxisol (EC 50 = 141.9 and 1835 mg AcPb kg − 1 , respectively). Folsomia candida was the least sensitive invertebrate species to AcPb in all soils. Among plant species, Z. mays was less sensitive (EC 50 = 1527.5 mg AcPb kg − 1 ) than P. vulgaris (EC 50 = 560.5 mg AcPb kg − 1 ) in the Oxisol. The present study evidenced that the toxicity of AcPb should not be attributed uniquely to the presence of Pb, as the treatment containing uniquely Ac provoked the same toxicity as the highest dose of AcPb. HighlightsLead acetate signi cantly affected all standard species tested Enchytraeus crypticus was the most sensitive species in all tested soils Zea mays was less sensitive to AcPb than Phaseolus vulgaris K-acetate equivalent to the highest AcPb dose was as toxic as the highest AcPb dose

RESUMO. Este valor indica a necessidade de revisão da legislação atual e deve ser usado como ponto de partida para estudos futuros. Podendo-se afirmar que quanto maior as doses de Cr adicionadas nos solos maiores os teores de Cr presentes na planta. Apesar das culturas absorverem Cr em suas estruturas, grande parte deste fica ainda retido solo. PALAVRAS-CHAVE:Elementos traços, Dicromato de potássio, Valor de prevenção. 0,5,10,20, 45, 90, 200 and 400 mg kg -1 of dry soil) applied in solution in the form of dichromate K. The effects of treatments on the plants were evaluated by means of shoot height, root length, shoot dry weight, root dry weight. Data were subjected to non-linear models through the STATISTIC 7.0 software. The value of VP estimated in this study was 292 mg kg -1 for CXbd in maize, while the current value recommended by law is 75 mg kg -1 . This value indicates the need to review the current legislation and should be used as a starting point for future studies. It can be said that the higher the dose of Cr added in the largest land the Cr content present in the plant. Although the crops absorb Cr in their structures, much of this is still retained soil. DETERMINING THE VALUE OF PREVENTION FOR CHROMIUM IN THE STATE OF MINAS GERAIS SOILS ABSTRACT