ABSTRACT. Since orange is the most produced and consumed fruit in Brazil and since its position on the tree may influence its physical and chemical attributes, current assay modeled a three-dimension spatial variability of total soluble solids (TSS) and ascorbic acid (AA) contents of the fruit in an orange orchard according to fruit position (coordinates x, y and z) on the plant and analyzed solar radiation on them. The experiment was conducted in Nova Laranjeiras, Paraná State, Brazil, and analyzed 715 fruit (Monte Parnaso variety) from nine trees in 2011, 2012 and 2013. Results showed that high TSS contents were reported in the tree´s peripheral area in the two analyzed thirds due to a high solar radiation. Highest AA rates were reported in the apical third. In the case of quadrants, higher AA levels were found in SE and NE (morning sun) with regard to the apical third and in SW and SE (afternoon sun) with regard to the basal third. The three-dimension interpolation method displays the spatial variability of the fruit's physical attributes by three-dimensional maps.Keywords: ascorbic acid, fruit position, geostatistics, total soluble solids.Mapas temáticos 3D dos parâmetros químicos de frutos de laranjeira RESUMO. Considerando que a laranja é a fruta de maior produção e consumo no Brasil e que, a posição do fruto na planta pode influenciar suas características químicas, o objetivo deste trabalho foi modelar a variabilidade espacial tridimensional do teor de Sólidos Solúveis Totais (SST) e teor de Ácido Ascórbico (AA) de frutos em pomar de laranjas em função da posição (coordenadas x, y e z) dos frutos na planta e dos níveis de radiação solar incidente nos mesmos. O experimento foi conduzido no município de Nova Laranjeiras -PR, por meio da análise de 715 frutos (variedade Monte Parnaso) provenientes de nove árvores, nos anos de 2011, 2012 e 2013. Os resultados evidenciaram que maiores teores de SST são encontrados na área periférica da árvore em ambos os terços analisados, devido à maior incidência de radiação solar. Para os teores de AA, maiores valores foram encontrados no terço apical em relação ao terço basal. Em relação aos quadrantes, maiores teores de AA são encontrados nos quadrantes SE e NE (sol da manhã) para o terço apical e nos quadrantes SO e SE (sol da tarde) para o terço basal. O uso de metodologia de interpolação tridimensional permite a visualização, por meio de mapas tridimensionais, da variabilidade espacial de atributos químicos de frutos.Palavras-chave: ácido ascórbico, posição do fruto, geoestatística, sólidos solúveis totais.

A GPS receiver and a total station were used to measure the spatial location of the fruit and to determine which quadrant they were located in. In this experiment, 13 trees were studied. Twelve fruits were evaluated in each geographical quadrant, and 156 fruits were considered. After harvest, the productivity was expressed as kg per quadrant (kg quadrant -1 ). Next, physical tests (equatorial diameter (EqD), total fruit mass (TFM), juice yield (JY)) and chemical tests (total soluble solids (TSS), total titrable acidity (TTA), the TSS/TTA ratio, and the ascorbic acid (AA) content) were conducted in the laboratory. In addition, the data were subjected to analysis by descriptive statistics and geostatistics to determine the spatial variability of the physical and chemical properties of the oranges, the variations of the soil properties and the correlations between the following parameters: the pH properties of the fruit and Zn; TFM and K; EqD and K, and C and TSS. The orchard varies spatially, especially regarding the EqD, TFM, JcP, TSS and AA for the quadrants with the highest values (the Northwest, Southeast, Northeast, Southwest and Southeast, respectively). The soil potassium and zinc contents were strongly correlated with the physical and chemical properties of the orange fruits.

No Pará a atividade de mandiocultura exerce forte influencia socioeconômica e alimentar para muitas famílias. Contudo sabe-se que o rendimento por hectare no estado ainda é aquém do esperado, pois um dos limitantes de produtividade são as formas de manejo, podendo ocasionar boas ou más alterações na estrutura do solo, devido à complexidade e interação entre seus atributos físicos, químicos e biológicos. Assim, o objetivo neste estudo foi avaliar os atributos físicos do solo em plantio de mandioca sob manejo diferenciado com o uso de estatística multivariada. A área experimental está localizada na comunidade de Boa Esperança, município de Santarém, estado do Pará, Brasil, sendo avaliado as práticas de manejo: controle de plantas infestantes, diferentes sistemas de irrigação, correção de acidez do solo e densidade populacional, onde foram coletadas amostras deformadas compostas na profundidade de 0-20 cm e amostras indeformadas de 0-5 e 15-20 cm por parcela. Foram determinados a granulometria, densidade do solo, densidade de partícula e porosidade total. Os dados foram submetidos a estatística descritiva e análise de componentes principais, sendo que nos componentes principais foram identificados a formação de grupos apenas nos tratamentos com capina manual e testemunha. O tratamento testemunha demonstrou a diminuição da densidade do solo, mas neste mesmo manejo se observou o aumento da densidade do solo com a adição de cálcario. Enquanto que no tratamento com capina manual + calcário apresentou baixa densidade do solo.

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The management of soil organic matter (SOM) is fundamental in agriculture for soil conservation and crop yields. However, in addition the soil being dynamics, it is heterogeneous, therefore, understanding the spatial variability of SOM is essential. The main objective of this study was to evaluate the spatial variability of SOM in a cassava cultivation under different management, seeking to classify its spatial dependence by geostatistics. A filed experiment was conducted out on soil classified as oxisol with four different management systems: irrigation (micro sprinkler, drip and no irrigation), spacing (1.0 × 0.8 m, 1.0 × 1.0 m and 1.0 × 1.5 m), weed control (manual control and no control) and acidity correction (limestone and withouth limestone), totaling 36 experimental plots. To determine the SOM, the wet oxidation method was used, and the semivariograms were generated by the GS+® software. The effect of the different management systems on the spatial variability of the SOM was evaluated at a depth of 0.0-0.2 m. The theoretical semivariogram model that best fitted the study was the Gaussian model, with a well-defined level, also expressing the condition of data stationarity. The spatial dependence was classified as strong and, through the thematic map generated from the kriging, it was possible to observe the variability in the SOM content for different management zones. The use of geostatistics techniques provided important information for understanding the spatial distribution of soil organic matter.

Nutrient management becomes essential in soils with low natural fertility, so the use of organic fertilizers can improve chemical properties of soil and reduce production costs. The objective of this study was to evaluate the effect of different fertilization sources on the chemical properties of soil under cassava cultivation. The experiment was conducted between 2017/2018 in the community of Boa Esperança, Santarém-PA using the cultivar Bem-te-vi, in the randomized block design with 4 treatments: T1 (without fertilization), T2 (fertilization NPK), T3 (organic fertilization with poultry manure), T4 (fertilization with cattle manure), with 5 replicates. The soil samples were analyzed for the contents K+, Ca²+, pH in H2O and KCl, Al³+ and soil organic carbon content (TOC). The data were submitted to analysis of variance and the means were compared by the Tukey test at 5% probability, using the software MINITAB© version 18. There were statistical differences between the treatments for all the chemical properties analyzed. The findings of the analysis were that fertilization with catle manure and NPK were the same and differed from the other treatments for the contents of K+, pH in H2O and KCl, for Ca²+ and TOC. The treatment without fertilization obtained the lowest values differing from the others, for Al³+. The source from NPK obtained the lowest content in the soil. The treatments with organic fertilizers had higher levels of the above nutrients in the soil. The chemical properties of the soil were altered from the different management systems for the cultivation of cassava.

Precision agriculture (PA) is used as a tool in the citrus industry and aims to increase production reduce costs and search for answers to explain the spatial variability of yield. The aim of this study was to model the spatial variability of yield and physical properties of fruits of orange trees in relation to the geographic quadrant where the fruits are on the trees. The experiment was carried out in a 1 ha commercial orchard of orange trees cv. Monte Parnaso. A GPS receiver and a total station were used to georeference the experimental area and the position of each sampled tree in the area, as well as the location of the geographic quadrant where the fruits sampled were on the trees. Twelve fruits were collected from each of the 13 sampled trees, resulting 39 fruits per quadrant, totalling 156 fruits each crop-year (2011 and 2012). Yield was estimated after the harvest (kg.quadrant -1 ). Physical analyses were performed for each fruit, measuring the following physical properties: equatorial diameter, total mass and juice yield. We conducted analysis of descriptive statistics and spatial variability in the data through techniques related to geostatistics. The results showed the highest spatial variability between the quarters for the juice yield and yield, and the verified juice yield was within the acceptable standard by regulatory bodies.

Aims: Knowledge is currently low about composition, richness and abundance of native plant species from secondary forests in traditional communities in the Tapajós River Basin, Western Amazon. These forests are of great importance to indigenous populations being niches of resistance to the advances of monocultures. The objective of this work was to evaluate the floristic composition of a secondary forest with typical indigenous extractive interventions. Study Design: The secondary forest studied located in indigenous Village. This forest had 15 years of natural regeneration and was therefore an anthropized forest, where the indigenous people removed wood, fibers, oils and fruits, thus characterizing the agroextractivism on this environment and a very particular floristic composition always in evolution. Place and Duration of Study: The research was in Santarem city, Pará state, in Ipaupixuna Village (02°32´46” S, 54°20'15” W) between June 2019 to December 2019. Methodology: The research had a descriptive approach for floristic study, but in the same time had a quantitative point of view with the use of regression analysis. The parameters evaluated were: 1. Species abundance, 2. Floristic Richness; 3. Plant diversity measured by the Jentsch Mixing Coefficient; 4. Relations between Circumference & Height of trees. The size of the sampled area was 1 (one) hectare of secondary forest. Results: A high abundance was found for Tapirira guianensis Aubl followed by Buchenavia huberi Ducke and Bellucia grossularioides (L.) Triana. Fabaceae was the family of greatest quantitative expression in this 15-year-old secondary forest in indigenous landscapes followed by Arecaceae. Conclusion: The secondary forest studied of 15 years of natural regeneration and random anthropogenic interventions by agroextractivists activities of Munduruku Indigenous people showed medium floristic richness and low floristic diversity. Interventions to enrich this secondary forest with plant species with high economic potential can bring environmental and economic benefits to these indigenous people.