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The objective was to verify the performance of spectral techniques as well as validation models in the prediction of nitrogen, total organic carbon, and humic fractions under different cultivation conditions. Chemical analyses for the determination of nitrate, total nitrogen, total organic carbon, and the chemical fractionation of soil organic matter were performed, as well as spectral analyses by Vis-NIR-SWIR and X-ray fluorescence. The results of the spectroscopy were processed using RStudio v. 4.1.3, and PLSR and support vector machine learning algorithms were applied to validate the models. The Vis-NIR-SWIR and XRF spectroscopic techniques showed high performance and are indicated for the prediction of nitrogen, total organic carbon, and humic fractions in Ferralsols of medium sandy texture. However, it is important to highlight that each technique has its own characteristic mechanism of action: Vis-NIR-SWIR detects the element based on harmonic tones, while XRF is based on the atomic number of the element or elemental association. The PLSR and SVM models showed excellent validation results, allowing them to fit the experimental data, emphasizing that they are different statistical methods. [ABSTRACT FROM AUTHOR]

Pedological maps in suitable scales are scarce in most countries due to the high costs involved in soil surveying. Therefore, methods for surveying and mapping must be developed to overpass the cartographic material obtention. In this sense, this work aims at assessing a digital soil map (DSM) built by multispectral data extrapolation from a source area to a target area using the ASTER time series modeling technique. For that process, eight representative toposequences were established in two contiguous micro-watersheds, with a total of 42 soil profiles for analyses and classification. We found Ferralsols, Plinthosols, Regosols, and a few Cambisols, Arenosols, Gleisols, and Histosols, typical of tropical regions. In the laboratory, surface soil samples were submitted to spectral readings from 0.40 µm to 2.50 µm. The soil spectra were morphologically interpreted, identifying shapes and main features typical of tropical soils. Soil texture grouped the curves by cluster analysis, forming a spectral library (SL). In parallel, an ASTER time series (2001, 2004, and 2006) was processed, generating a bare soil synthetic soil image (SySI) covering 39.7% of the target area. Multiple Endmember Spectral Mixture Analysis modeled the SL on the SySI generating DSM with 73% of Kappa index, in which identified about 77% is covered by rhodic Ferralsols. Besides the overestimation, the DSM represented the study area's pedodiversity. Given the discussion raised, we consider including subsoil data and other features using other sensors in operations modeled by machine learning algorithms to improve results. [ABSTRACT FROM AUTHOR]

Brazil is one of the major passion fruit producers worldwide. Viral diseases are among the most important constraints for passion fruit production. Here we identify and characterize a new passion fruit infecting-virus belonging to the family Geminiviridae: passion fruit chlorotic mottle virus (PCMoV). PCMoV is a divergent geminivirus unlike previously characterized passion fruit-infecting geminiviruses that belonged to the genus Begomovirus. Among the presently known geminiviruses, it is most closely related to, and shares ~62% genome-wide identity with citrus chlorotic dwarf associated virus (CCDaV) and camelia chlorotic dwarf associated virus (CaCDaV). The 3743 nt PCMoV genome encodes a capsid protein (CP) and replication-associated protein (Rep) that respectively share 56 and 60% amino acid identity with those encoded by CaCDaV. The CPs of PCMoV, CCDaV, and CaCDaV cluster with those of begomovirus whereas their Reps with those of becurtoviruses. Hence, these viruses likely represent a lineage of recombinant begomo-like and becurto-like ancestral viruses. Furthermore, PCMoV, CCDaV, and CaCDaV genomes are ~12–30% larger than monopartite geminiviruses and this is primarily due to the encoded movement protein (MP; 891–921 nt) and this MP is most closely related to that encoded by the DNA-B component of bipartite begomoviruses. Hence, PCMoV, CCDaV, and CaCDaV lineage of viruses may represent molecules in an intermediary step in the evolution of bipartite begomoviruses (~5.3 kb) from monopartite geminiviruses (~2.7–3 kb). An infectious clone of PCMoV systemically infected Nicotiana benthamina, Arabidopsis thaliana, and Passiflora edulis. [ABSTRACT FROM AUTHOR]