Este trabalho apresenta uma contribuição aos aspectos da climatologia dinâmica da Amazônia oriental, baseado na análise observacional das séries históricas de 40 anos (1975 a 2014) dos dados de precipitação para 30 estações meteorológicas dos estados do Pará, Maranhão e Tocantins. Os resultados mostraram que os padrões climatológicos de precipitação nos regimes chuvoso (janeiro a maio) e seco (julho a novembro) apresentam variabilidade espacial pronunciada, com características climáticas diferenciadas (intensidade e disposição geográfica dos máximos e mínimos pluviométricos) entre os dois regimes sazonais. Os dados de precipitação do satélite TRMM indicaram que a ZCIT e a ZCAS são os principais sistemas meteorológicos do regime chuvoso, enquanto que os aglomerados convectivos, linhas de instabilidade e influências das bandas frontais posicionadas no nordeste brasileiro são os principais sistemas que explicam a distribuição pluviométrica do regime seco. A análise de tendências usando o teste de Mann-Kendall para o regime chuvoso demonstrou sinais de aumento sistemático de precipitação particularmente no oeste, centro e nordeste do Pará e norte do Tocantins. Para o regime seco, há sinais de tendências positivas significantes no oeste/sudeste do Pará, contudo ressaltam-se os padrões de neutralidade (sem tendências) em grande parte do Maranhão e alguns setores do norte/nordeste do Pará.

Development duration in the cactus is directly related to changes in the environment caused by the management, which can result in advancing or delaying the harvest. The aim of this study was to analyse the growth, phenology and cutting time of irrigated cactus intercropped with millet, with and without the use of mulch. The experimental design was of randomised blocks (regular arrangement) with four treatments: monocropped cactus, and intercropped cactus and millet, both with and without mulch. The cladode area index and dry matter were used to calculate the morphophysiological indices. The total number of cladodes on the plant was used to delimit the phenological phases. The ideal cutting time for the crop was determined from the dry matter. Under the monocrop system with mulch, the cactus was superior to the other systems regarding morphophysiological indices. The intercrop caused a reduction in phenophase 2 of the cactus and the advancement of phenophase 3, but there was no reduction in crop yield. The ideal cutting time was between 2,300 and 2,400°C day. The irrigated intercropping of cactus and millet advances the cutting time of the forage cactus, irrespective of the use of mulching.

Cowpea has great socioeconomic importance in the northeastern part of Pará state. However, in order to provide suitable irrigation management during the dry period this region requires solid information regarding water demand by regional crops. This research aims to determine the water demand, the crop coefficient (Kc) and the uncoupling factor during the different development stages of cowpea in the northeast of Pará. The crop evapotranspiration (ETc) was measured by drainage lysimeters. This information was coupled to the reference evapotranspiration (ETo) to obtain the crop coefficients, which were used to adjust the model function of accumulated degree-days and the leaf area index (LAI). The uncoupling factor was estimated to indicate the factors that control evapotranspiration. The ETc values reached a cumulative total of 267.73 mm ± 10.21 mm during the cowpea cycle. The average value of the uncoupling factor was 0.66. This indicates that the cowpea crop does not fully uncouple from the atmosphere underneath the climatic conditions in northeast Pará. The cowpea Kc values presented averages of 0.8, 1.4 and 0.8 in the vegetative phase, reproductive phase and final stage, respectively. The Gaussian model showed an excellent fit for the estimation of Kc values based on accumulated degree days and the LAI. These amounts differ from others found in the literature. Therefore, it reinforces the necessity for an assessment of crop coefficients under local conditions and for the employment of more precise methods.

The focus of this work is on small municipalities (population below 50 thousand inhabitants) that cover around 87% of the territory of the Brazilian Legal Amazon (BLA). Based on a comprehensive integrated analysis approach using the three components hazard (climate extremes from CMIP6 future scenarios), exposure (directly affected population), and vulnerability (subdimensions of susceptibility and coping/adaptive capacity by using multidimensional indicators), the latter two using current datasets provided by the official Census IBGE 2022, we document a quantitative assessment of the risk R of natural disasters in the BLA region. We evidenced a worrying and imminent intensification of the curve of R in most Amazonian municipalities over the next two 25-year periods. The overall results of the highest proportions of R (total municipalities affected) pointed out the Amazonas, Roraima, Pará, and Maranhão as the main states, presenting projected categories of R high in the near future (2015 to 2039) and very high in the far future (2040 to 2064). The detailed assessment of the susceptibility and coping/adaptive capacity allowed us to elucidate the principal indicators that aggravate the degree of vulnerability: economy, the precariousness of urban infrastructure, medical services, communication, and urban mobility, whose combined factors, unfortunately, reveal a widespread poverty profile along the small Amazonian municipalities. Our scientific findings can assist decision makers in targeted strategies planning and public policies to minimize and mitigate ongoing and future climate change.

Objetivou-se determinar os modelos que melhor descrevem a relação entre as dimensões lineares e a área foliar da mangueira, cultivar Tommy Atkins, além de estabelecer o fator de correção. A pesquisa foi conduzida na Fazenda Experimental da Universidade Federal Rural da Amazônia, na vila de Cuiarana, município de Salinópolis. Foram analisadas de 90 a 150 folhas, em 11 árvores de um campo experimental, determinando-se o comprimento e a largura máxima das folhas. A área foliar real foi determinada usando o integrador de área foliar "Area Meter" (AM 300). O fator de correção foi obtido pela divisão da área foliar real pela área foliar calculada. A área foliar foi também estimada por meio de modelos linear e não linear. Os modelos gerados apresentaram ótimo desempenho, com valores de R² entre 90 e 97%. O fator de correção de 0,71 pode ser utilizado para estimar a área foliar real da mangueira, multiplicado pelas medidas lineares. Os modelos que utilizaram o produto das dimensões como variável independente apresentaram valores de R² superiores aos que utilizaram apenas uma das dimensões, sendo o tipo cúbico o mais preciso.

This work evaluated the effect of soil water availability on growth and productivity variables of cowpea in northeastern Pará, Brazil. The experiment was carried out in a field of 2,100 m2 at the experimental site of the Federal Rural University of Amazon, during the driest season of the years 2011, 2012 and 2013, in a completely randomised design with two treatments (irrigated and non-irrigated), both with 12 replications in the reproductive phase (2012 and 2013). Growth and productivity data were submitted to analysis of variance with two variation factors (water regime and experimental year) at 5% probability. Student's t -test at 5% probability was used in the means of the stomatal conductance data, since this was monitored only in 2012. Final biomass production presented a reduction of 54.3% in 2012 and 26.4% in 2013 as a result of water deficit (DEF) of 76 and 26 mm, respectively. Mean stomatal conductance was reduced by 73% in the grain-filling stage as a result of the lower water availability during this period. Average cowpea productivity under water deficit reached 1,257 kg ha-1 in 2012 and 1,396 kg ha-1 in 2013. The reduction in water supply over the reproductive period significantly decreased production by 72 and 41% (F test, p < 0.05) in 2012 and 2013, respectively. An accumulated water deficit during the reproductive phase caused a maximum LAI reduction of 47% in 2012 (DEF of 76 mm) and of 13% in 2013 (DEF of 26 mm).