The study aimed to characterize the spatial structure of variability of biophysical indexes of vegetation through images obtained by Unmanned Aerial Vehicles under strong heterogeneity and anisotropy, using geostatistical procedures. Plots with different types and densities of culture were evaluated in a didactic vegetable garden. Five vegetation indexes obtained from aerial multispectral camera images were evaluated parallel with geostatistical analysis and anisotropy investigation for multiscale spatial modeling. For the studied domain, geometric anisotropy was identified for the biometric indexes. The spherical model presented a better fit when anisotropy was not considered, whereas the exponential model had the best performance in the anisotropic analysis. Contrasting targets were better identified in multispectral images and considering anisotropy. The Soil-Adjusted Vegetation Index is recommended for similar applications.

The spectrally active components of the soil allow the realization of integrative analyzes of soil aspects such as their classification. The purpose of this study was to evaluate the separation of soil classes from spectral reflectance data using principal components analysis (PCA). The study was carried out in the Aiuaba Experimental Basin located in the municipality of Aiuaba, Ceará, Brazil. Soil samples were collected in Ustalfs, Ustults and Ustorthents profiles. The samples were submitted to spectral analysis by a spectroradiometer and, subsequently, to PCA. Principal components were used to identify which of them contribute more significantly to the separation of the soil classes analyzed, based on their relationship with the soil attributes using a two-dimensional graphical analysis. From the examination of spectral behavior data of the different soil classes, the use of PCA allowed the separation of the classes Ustorthents, Ustalfs and Ustults from each other.

For a variety of agronomic reasons, landraces have strategic importance for cowpea Vigna unguiculata (L.) Walp. genetic breeding programs. The aim of the current research was to identify black aphid, Aphis craccivora Koch resistance in cowpea landraces. Twenty-three landraces from different regions of the state of Ceará, Brazil, were compared to four literature-cited standards: BRS Guariba and TVu 408 P2 (resistant); BR 17-Gurguéia and VITA 7 (susceptible). Experiments were conducted in a greenhouse located at Campus do Pici, Universidade Federal do Ceará, in Fortaleza, Ceará state, Brazil. A completely randomized block design was used, with six replicates, each composed of one plant in a 300 mL pot. Plants were individually infested with five six-day-old adult insects. Adults were subsequently evaluated two days after infestation and nymphs at four days. Six landraces were highly resistant (Um-named 1-DIP, Feijão de arrancada, Feijão moitinha, Feijão de moita, Cara preta and Roxim miúdo) to levels compatible to the BRS Guariba standard. Three other landraces (Feijão da Bahia, Cojó and Feijão da Consuelo Rocha) showed moderate resistance, similar to the TVu 408 P2 standard. In addition to the high genetic variability found in the landraces, antibiosis was the main resistance mechanism observed.

The objective of this work was to evaluate the temporal stability of total organic carbon (TOC) of soils under different uses in areas with Caatinga vegetation. The experiment was conducted in an experimental farm that encompasses a watershed in the Curu River Valley, in Pentecoste, state of Ceara, Brazil. Soil samples were collected in two areas with Caatinga vegetation under different uses-one with a 35-year preserved area (CP35) and one with a 30-year pasture area (CR30)-and the sampling points were distributed using a 30×30 m uniform grid. Soil samples of the 0-0.2 m layer were collected between February 2016 and April 2017 to determine TOC; and nonparametric Spearman's correlation, mean relative difference (MRD), and temporal stability index (TSI) tests were applied to evaluate TOC stability. The Spearman's test showed a higher correlation between collection dates for CR30 than for CP35. The DRM showed more points with relative differences approaching zero for CP35, and more points with lower standard deviation for CR30. The TSI indicated a greater number of points to be used for CR30 because they have better temporal stability. Therefore, the TOC of the CR30 has better temporal stability than that of the CP35, presenting TSI of approximately 1.5-fold that of the CP35. The thinning of the vegetation in CR30 homogenized the soil TOC, whereas the fallow area, which were preserved, had greater heterogeneity.

Sambaquis are Brazilian archaeological sites whose matrix is predominantly composed of shells, accumulated and mixed with various kinds of debris. They are formed by the anthropogenic deposition of mollusk exoskeletons, plant remains, charcoal, tools, and ceramics, among other marks of human intervention. These shell mounds usually have overlying soils with dark-colored horizons rich in organic matter and high in fertility, called Archaeological Dark Earths (ADE). One of the oldest and most significant records of sambaquis in Brazil, known and [...] ABSTRACT Sambaquis are Brazilian archaeological sites whose matrix is predominantly composed of shells, accumulated and mixed with various kinds of debris. They are formed by the anthropogenic deposition of mollusk exoskeletons, plant remains, charcoal, tools, and ceramics, among other marks of human intervention. These shell mounds usually have overlying soils with dark-colored horizons rich in organic matter and high in fertility, called Archaeological Dark Earths (ADE). One of the oldest and most significant records of sambaquis in Brazil, known and