Mining activities, while economically important, have caused significant soil degradation, affecting soil quality, ecosystem functioning, and sustainability in Andean ecosystems. This study developed an integral soil quality index based on physicochemical, microbiological, and nematode indicators to assess soil degradation in the Ollachea mining area, Peru. We collected soil samples from four land-use systems (natural pasture, Zea mays cultivation, Ficus sp. cultivation, and Eucalyptus sp. forest) during two dry and two rainy seasons. The proposed index integrates complementary indicators related to soil chemical properties, nutrient availability, metal contamination, microbial activity, and nematode community structure to characterize soil quality and detect ecological stress associated with mining disturbance. The results showed that the index effectively discriminated soil quality by land use and season, with Eucalyptus sp. forest soils showing the highest soil quality status, whereas cultivated and mining-impacted soils exhibited lower quality associated with greater environmental stress. The main contributors to soil stress were related to microbial and metal-associated indicators, particularly total actinomycetes (6.53), Al (1.87), and Fe (1.65), highlighting their relevance in mining-impacted soils. Furthermore, nematode-based biological responses increased the index's sensitivity to seasonal ecological changes. Compared with other soil quality indices, the proposed integral index performed better, showing strong correlations with soil quality patterns in both dry and rainy seasons (r = 0.97 and r = 0.95, respectively). Overall, this study shows that a nematode-enhanced integral soil quality index provides a robust, transferable approach for monitoring mining-impacted soils and supporting ecological restoration strategies in Andean ecosystems.
In semi-arid coastal regions, groundwater mineralization limits water-usage opportunities because of the intersection of natural hydrogeochemical processes with agricultural and urban pressures. The present study analyzed groundwater quality in 25 wells of the Sullana aquifer in northern Peru, within the context of a dry-season campaign. Physicochemical characterization incorporated ionic ratios, the cationic Gibbs relationship, principal component analysis, hierarchical cluster analysis, a weighted arithmetic Water Quality Index, irrigation indicators, and spatial analysis on GIS. Results of our study showed the electric conductivity in the range of 656 - 17290 µS/cm and total chloride amounts of up to 4522.60 mg/L. Comparison data on the electric conductivity showed exceedance for 44% of wells, 40% for total dissolved solids, 88% for chloride levels, and 56% for sulfate levels. The total variance is accounted for by two primary components at 78.46%, where major-ion mineralization is demarcated from Fe–Mn variability. The Water Quality Index labels some 84% of wells either poorly, very poorly, or unsuitable for drinking water due to untreated conditions. Manganese was present in three wells at over 0.40 mg/L, while certain As, Pb, Cd, and Cu findings remain uncertain and need confirmation through calculations based on laboratory reporting parameters, detection parameters, and quantification parameters, Major-ion mineralization and localized manganese accumulation remained as the two main issues regarding the quality of groundwater, causing the necessity for seasonal tracking, hydro-geological monitoring, and more hydrochemical analysis or isotopic tracing for better understanding of salinity origins and leading the way to sustainable extraction of ground waters in the future.
Abstract The squash ( Cucurbita moschata ), a landrace crop with a denomination of origin in Lambayeque, Peru, represents a valuable genetic resource with potential for tolerance or resistance to potyviruses. Among these, Zucchini yellow mosaic virus (ZYMV) is one of the most destructive viral pathogens affecting cucurbits worldwide. This study aimed to develop and validate a diagrammatic ordinal scale for assessing ZYMV disease severity under field conditions and to identify resistant accessions. In 2024, sixteen accessions were evaluated under natural infection in an experimental field of the Vegetable Research Program at the Universidad Nacional Agraria La Molina, Peru. Following previous virus confirmation via RT-PCR and HTS sequencing, disease monitoring included symptom characterization and virus detection by DAS-ELISA, which confirmed a high incidence of ZYMV. Utilizing a dataset of 40 leaf samples representing different severity levels, a four-level ordinal diagrammatic scale was developed by integrating visual foliar symptomatology with relative viral concentration (optical density) obtained from DAS-ELISA. The scale was validated through field evaluations using independent raters, and its reliability was assessed using Fleiss' kappa and Cohen's kappa statistics. The proposed scale demonstrated high biological accuracy, revealing a strong, highly significant correlation between visual severity levels and serological viral concentration (Spearman's ρ = 0.937, p < 0.0001). Inter-rater reliability assessments confirmed strong overall reproducibility among independent evaluators (Fleiss' kappa = 0.608, p < 0.001). Statistical analysis revealed a highly significant differential response among genotypes; accession C44 exhibited the lowest and most stable severity levels, closely followed by C09, establishing them as highly promising sources of resistance. This study provides a reliable tool for ZYMV severity assessment and supports the identification of genetic resources for resistance breeding programs in cucurbits. The scale developed in this study will help standardize symptom assessment and improve the identification and selection of resistant plant materials, thereby enhancing the efficiency of resistance breeding programs.
Chemical seed treatment is widely used to manage diseases and pests during the early stages of crop development. However, the integration of this practice with biological agents may be limited by incompatibility between chemical products and beneficial microorganisms. The objective of this study was to evaluate the compatibility of chemical seed treatments with the biological agents Trichoderma harzianum, Paecilomyces lilacinus, Bacillus subtilis, Azospirillum brasilense, and Bradyrhizobium japonicum using seeds of soybean cultivar NS 6700. Seeds were subjected to different chemical treatments and subsequently inoculated with the microorganisms. Compatibility was assessed through the percentage of microbial growth on treated seeds incubated on culture medium and by determining the minimum inhibitory concentration (MIC) using the broth microdilution method. The results demonstrated that compatibility was highly dependent on the chemical formulation evaluated. The treatment containing thiophanate-methyl + fluazinam showed high compatibility with the fungal antagonists, allowing 88% growth of both T. harzianum and P. lilacinus, whereas the formulation composed of pyraclostrobin + thiophanate-methyl + fipronil supported 83% growth of T. harzianum and 100% growth of B. subtilis. In contrast, treatments containing carbendazim + thiram and thiophanate-methyl + fluazinam + fipronil completely inhibited the growth of all biological agents evaluated. MIC assays complemented the results observed in seed colonization, revealing marked differences in the sensitivity of biological agents to the chemical treatments. It can be concluded that compatibility between biological products and chemical seed treatments depends on the formulation used, and prior compatibility assessments are essential to ensure the successful integration of these technologies in agricultural production systems.
This is the first report on the isolation and full characterisation (i.e., morphological, molecular, virulence) of the entomopathogenic nematode/symbiotic bacterium complex, Steinernema carpocapsae / Xenorhabdus nematophila, in soils of the State of Hidalgo, Mexico. The nematode was characterised based on morphometrics with the aid of both light and scanning electron microscopy, and analysis of the internal transcribed spacer (ITS) region of the ribosomal DNA. The symbiotic bacterium was characterised based on its phenotypic characteristics (i.e., growth on nutrient agar plus bromothymol blue and triphenyltetrazolium chloride, and 17 biochemical tests) and analysis of the 16S rDNA gene sequencing. The constructed phylogenetic trees of both nematodes and bacteria were associated with bootstrap values of 99-100. The virulence of the infective juvenile (IJ) stages of the nematode was tested against larvae of Galleria mellonella at doses (IJ:larva): 1:1, 5:1, 10:1, 30:1, 60:1, and 100:1, resulting in mortality rates ranging from 22% (standard deviation, SD = 2) to 100% (SD = 1) in three days.
