Improving environmental sustainability involves measuring indices that show responses to different production processes and management types. Suspended sediment concentration (SSC) in water bodies is a parameter of great importance, as it is related to watercourse morphology, land use and occupation in river basins, and sediment transport and accumulation. Although already established, the methods used for acquiring such data in the field are costly. This hinders extrapolations along water bodies and reservoirs. Remote sensing is a feasible alternative to remedy these obstacles, as changes in suspended sediment concentrations are detectable by satellite images. Therefore, satellite image reflectance can be used to estimate SSC spatially and temporally. We used Sentinel-2 A and B imagery to estimate SSC for the Teles Pires River in Brazil’s Amazon. Sensor images used were matched to the same days as field sampling. Google Earth Engine (GEE), a tool that allows agility and flexibility, was used for data processing. Access to several data sources and processing robustness show that GEE can accurately estimate water quality parameters via remote sensing. The best SSC estimator was the reflectance of the B4 band corresponding to the red range of the visible spectrum, with the exponential model showing the best fit and accuracy.

The use of fire retardants increases efficiency in fighting forest fires, however, it still presents uncertainties regarding environmental contamination, recommendations for preparation, and it lack of regulation in Brazil. In this scenario, alternative products such as water-retaining polymers, that can reduce the rapid evaporation of water, can also have positive effects in terms of reducing fire behavior. Efficiency and ways of using the water-retaining polymer as a short-duration fire retardant (indirect combat) in controlled burns in eucalyptus plantations were evaluated. Five concentrations (dilution in water), three volumes of spray solution, and two post-application times on the combustible material available in the area were evaluated. Controlled burns were conducted downwind, between 10 am and 2 pm, during dry season in the region, with micrometeorological and fire behavior assessments (fire propagation speed and length of flames). Increased spray volume and concentration of water-retaining polymer led to reductions in the spread of fire. In eucalyptus combustible material, the water-retaining polymer can be used as a fire retardant of short duration (effective up to two hours after application), considering a spray volume of 2.0 L m-2 and concentration of 0.0060% (diluted in water).

Aiming to support projects and managements of irrigation for vegetables in the Mid-North region of Mato Grosso state, Brazil, this paper determined crop evapotranspiration (ETc), crop coefficients (Kc) and water response function of summer squash (Curcubita pepo) cv. ‘Italiana’ under different cultivation conditions. The plantations were conducted in the dry season of the region (July to October 2016), using 2.5 kg m^-2 of millet straw (grass) and crotalaria straw (legume) and bare soil. ETc was obtained by soil water balance through tensiometry, whereas Kc values were given by the ratio between ETc and the reference evapotranspiration (ETo) obtained by the FAO-56 Penman-Monteith method. For the water response function, the rates of 40, 60, 80, 100 and 120% ETc were applied, in which case the Class A pan method was used to obtain ETo. The different soil covers did not influence the ETc, Kc and accumulated thermal sum in the phenological stages of the summer squash. Kc values were 0.1, 0.25, 0.38 and 0.41, for the phenological stages I to IV, with average durations of 8, 46, 16, and 20 days, respectively. Increase in irrigation depths did not influence the rates of production of male and female flowers, but affected yield and decreased water use efficiency, regardless of soil cover.

O objetivo do trabalho foi calibrar e avaliar estatisticamente a equação simplificada de Angström-Prescott (AP) para estimativa da radiação global (Qg) com base na razão de insolação (n/N), em diferentes agrupamentos de dados, na Amazônia brasileira. O modelo AP, baseia-se nas relações entre a transmissividade atmosférica e a razão de insolação (Qg/Qo = a + b (n/N)), e possui dois coeficientes (linear e angular) que demandam calibrações regionais. Para tanto, foram usados dados de 20 estações meteorológicas (automáticas e convencionais) pertencentes a rede de estações do Instituto Nacional de Meteorologia (INMET), inseridas no bioma amazônico; as bases de dados foram separadas em agrupamentos total, anual e sazonal (seca, seca-chuva, chuva e chuva-seca), sendo considerados a proporção de 70 e 30% de dados para calibração e avaliação estatística do desempenho, respectivamente. Foram considerados os indicativos estatísticos erro relativo médio (MBE), quadrado da raiz do erro médio (RMSE) e índice de concordância de Willmott (d). Os coeficientes calibrados no agrupamento total (que considera todas as estações do bioma) geraram os piores desempenhos estatísticos na estimativa de Qg (com diferenças de até 36% entre os valores medidos e estimados), indicando a necessidade de avaliação por estação e não por bioma. Para cada estação, os coeficientes obtidos no agrupamento anual (total de dados da estação) apresentaram desempenhos estatísticos semelhantes aos coeficientes obtidos nos agrupamentos sazonais, independentemente da estação e da época do ano, sendo, portanto, recomendados pela simplicidade e facilidade de aplicação nas estimativas de Qg.

Objetivou-se revisar e propor o protocolo de viabilidade das sementes da Bertholletia excelsa pelo teste de tetrazólio. Sementes oriundas de plantio comercial propagado por enxertia com 16 anos de idade implantadas na Fazenda Iracema em Cláudia, MT, foram destegumentadas e cortadas longitudinalmente, depois foram hidratadas em água por imersão direta (ID) e papel toalha Germitest^® (PG) por 24 e 48 h e embebidas nas concentrações de 0,1 e 0,5% do sal de tetrazólio por 12 e 24 h no escuro à 30 °C. O delineamento experimental foi completamente randomizado em fatorial 2 x 2 x 2 x 2 (forma de embebição x tempo em embebição x tempo em solução de tetrazólio x concentração da solução de tetrazólio) com quatro repetições de 8 sementes. O teste de tetrazólio foi eficiente para colorir e identificar as sementes viáveis e inviáveis. A avaliação da viabilidade das sementes da B. excelsa destegumentadas e partidas ao meio foi melhor na condição de embebição com imersão direta em água por 24 h e concentração de 0,5% do sal tetrazólio por 24 h à 30 °C e embebição em papel toalha Germitest® por 24 h e concentração de 0,5% do sal tetrazólio por 12 h à 30 °C. Palavras-chave: Bertholletia excelsa Humb. & Bonpl; potencial fisiológico; sementes florestais; recalcitrância. VIABILITY OF BRAZIL NUTS SEEDS BY TETRAZOLIUM TEST   ABSTRACT: The objective was to review and propose the protocol of viability of Bertholletia excelsa seeds by tetrazolium test. Seeds from the commercial planting propagated by grafting with 16-year-old implanted at Fazenda Iracema in Cláudia, MT, were undegumented and cut longitudinally, then hydrated in water by direct immersion (ID) and Germitest® paper towel (PG) for 24 and 48 h and soaked in concentrations of 0.1 and 0.5% of tetrazolium salt for 12 and 24 h in the dark at 30 ° C. The experimental design was completely randomized in a factorial design 2 x 2 x 2 x 2 (soaking form x soaking time x time in tetrazolium solution x tetrazolium solution concentration) with four replications of 8 seeds. The tetrazolium test was efficient to color and identify viable and unviable seeds. The evaluation of viability of detegumented and cut longitudinally B. excelsa seeds was better in: direct soaking in water for 24 h and concentration of 0.5% of tetrazolium salt for 24 h at 30 ° C and soaking in Germitest® paper towels for 24 h and a concentration of 0.5% of the tetrazolium salt for 12 h at 30 ° C. Keywords: Bertholletia excelsa Humb. & Bonpl; physiological potential; forest seeds; recalcitrance.

Avaliou-se as taxas de crescimento de quatro cultivares de soja (duas transgênicas e duas convencionais) pela influência na soma térmica acumulada (graus-dias - GD) com semeaduras em diferentes épocas, em Latossolo vermelho-amarelo, na safra 14/15 na região Médio-Norte do Mato Grosso. Foram avaliadas as cultivares TMG 132 RR e GB 874 RR (transgênicas) e MSOY 8757 e MSOY 8866 (convencionais), ambas de ciclo tardio, em cinco épocas de semeadura, com intervalos decendiais (entre 18/10/14 até 27/11/14). Foram determinadas as taxas de IAF (Índice de área foliar), TCC (taxa de crescimento da cultura), TCR (taxa de crescimento relativo), TAL (taxa de assimilação líquida) e TCA (taxa de crescimento absoluto). Na obtenção de GD empregou-se o método de Ometto com temperaturas basais mínimas e máximas de 14 e 36 °C, respectivamente. Em geral, as correlações entre taxas de crescimento e GD foram expressas por polinômios de segunda e/ou terceira ordem, com percentuais de correlação superiores a 65%.Palavras-chave: análise de crescimento, fenologia, temperatura do ar, soma térmica acumulada. DEGREE-DAYS IN THE ESTIMATES OF GROWTH RATES OF FOUR SOYBEAN CULTIVARS IN DIFFERENT PLANTING DATES In order to evaluate four soybean cultivars growth rates (two transgenic and two conventional) based on accumulated degree-days (DDG) between the phenological phases, in Middle-North region of Mato Grosso, Brazil, in Oxisol Yellow dystrophic soil. Were evaluated two transgenic cultivars (TMG 132 and GB 874 RR) and two conventional (MSOY 8757 and MSOY 8866), both with late cycle in five sowing dates, with ten-day intervals (10 days) from 18 October, 14 to 27 November, 14. Was determined the following rates: LAI (leaf area index), TCC (growth rate of culture, expressed), TCR (relative growth rate) and TAL (net assimilation rate). In obtaining DDG used the Ometto method, based on minimum and maximum temperatures of 14 and 36 °C, respectively. In general, the polynomial regression of second and third order were obtained, with higher coefficients of determination (R2) for estimates of TAL and TCR.Keywords: growth analysis, phenology, air temperature, accumulated thermal. DOI: http://dx.doi.org/10.14583/2318-7670.v04n03a01