Big-leaf mahogany (Swietenia macrophylla King) is the woody species with the highest economic value in Latin America. Currently, it is subject to intensive exploitation, diminishing its natural populations. Due to this decline, the species is a preferred species for reforestation and establishment of commercial tropical plantations. Mycorrhizal symbiosis is a biotic factor scarcely studied in the ecology of this species. Therefore, the objective of this research was to identify the diversity of arbuscular mycorrhizal fungi (AMF) species associated with the rhizosphere of seedlings and mature trees of big-leaf mahogany growing in its natural habitat, a tropical rain forest in Los Tuxtlas, Veracruz, Mexico. Soil samples from a 20-cm depth were taken from the rhizosphere of big-leaf mahogany seedlings and mature trees. Additionally, spores from the rhizosphere soil were propagated on Sorghum vulgare, isolated and identified. The percentage of AMF colonization was also evaluated.

Water contamination is a phenomenon of global concern resulting from human activities. Coliform bacteria reduce water quality and negatively affect public health. The pollution of surface and groundwater by coliform bacteria, including Escherichia coli , originate, in general, from point sources of pollution derived from human settlements, such as those located in Module I-1, Irrigation District 035, La Antigua, Veracruz, Mexico. The objective of this study was to assess the level of contamination of surface and groundwater by coliform bacteria and E. coli , as well as to identify point sources of water contamination by these bacteria in the sugarcane agroecosystem of Irrigation Module I-1, La Antigua. Sampling sites included deep wells, irrigation canals and natural streams near point sources of pollution. The determination of total coliform bacteria and E . coli were made in accordance with Mexican Standard NMX-AA-042-1987. Total coliform results revealed differences between groundwater (198.6 MPN/100 mL) and surface water concentrations (52,419.2 MPN/100 mL) (p < 0.05), and between irrigation water (76,501.1 MPN/100 mL) and concentrations in natural streams (28,337.3 MPN/100 mL). The highest concentration of E. coli was found in groundwater and surface water samples from the municipality of La Antigua. The primary sources of contamination are the discharges from drains and septic tanks. Total coliform values exceeded permissible limits established by NOM-127-SSA1-1994 that regulates the permissible water quality limits for human use and consumption. The presence of E. coli represents a significant public health risk.

In Mexico there are wild and domesticated populations of Carica papaya; however, studies related to its variation in situ have been limited in number of both individuals and geographic areas. The objective of this study was to characterize in situ the morphological variation of C. papaya specimens native to Mexico. Twelve morphological characteristics (six quantitative and six qualitative) of fruits collected from 222 specimens of C. papaya from 10 states of the slopes of the Pacific and the Gulf of Mexico were evaluated. Analysis of variance, principal component (PCA) and hierarchical grouping with euclidean distances were performed. According to the analysis of variance, all the morphological characteristics between accessions showed significant differences (P ≤ 0.01). The PCA revealed that the characteristics of greater contribution to the variation among the evaluated specimens were edible volume, diameter of the central cavity, length, diameter, thickness of pulp, shape of the peduncular end and fruit shape. The cluster analysis formed three statistically different phenotypic groups (P ≤ 0.01) and detected continuity based on the dimensions and shape of the fruit. Both multivariate analyses showed differences between the wild and domesticated types collected in homegardens. The high morphological variability among C. papaya is appropriate to establish a national germplasm conservation program of genotypes with genetic dissimilarity to be used in breeding programs. En México existen poblaciones silvestres y domesticadas de Carica papaya; sin embargo, los estudios relacionados con su variación in situ han sido limitados en número tanto de ejemplares como de zonas geográficas. El objetivo del presente estudio fue caracterizar in situ la variación morfológica de ejemplares de C. papaya nativos de México. Se evaluaron 12 características morfológicas (seis cuantitativas y seis cualitativas) de frutos recolectados de 222 ejemplares de papayos nativos provenientes de 10 estados de las vertientes del Pacífico y Golfo de México. Se realizaron análisis de varianza, de componentes principales (ACP) y de agrupamiento jerárquico con distancias euclidianas. De acuerdo con el análisis de varianza, todas las características morfológicas entre recolectas presentaron diferencias significativas (P ≤ 0.01). El ACP reveló que las características de mayor contribución a la variación entre los ejemplares analizados fueron volumen comestible, diámetro de cavidad central, longitud, diámetro, grosor de pulpa, forma del extremo peduncular y forma del fruto. El análisis de conglomerados formó tres grupos fenotípicos estadísticamente diferentes (P ≤ 0.01) y detectó continuidad con base en dimensiones y forma del fruto. Ambos análisis multivariados diferenciaron entre tipos silvestres y domesticados recolectados en huertos familiares. La alta variabilidad morfológica entre C. papaya es apropiada para establecer un programa nacional de conservación de germoplasma de genotipos con disimilitud genética para usarse en programas de mejoramiento genético.

Background. Taro (Colocasia esculenta L. Schott) is an economical import crop in Actopan, Veracruz, since it is exported to the United States of America (USA) and Canada. In Mexico, there is no regulation to implement traceability systems in agricultural products. Objective. To propose a traceability system in the supply chain of taro produced in Veracruz. Methodology. A questionnaire was designed to obtain information related to the production process; a second questionnaire asked about the packaging information; twenty-four producers and eight packinghouse managers were interviewed. Results and discussion. Producers have been growing taro for 10 years, they do not have any specific planting season and grow the variety Coco. No soil analysis is performed, irrigation is by flooding and the main pest is the mouse (Apodemus sylvaticus). Each producer makes an agreement with a packing house; the company performs the harvesting and then the packaging process. Wooden pallets are used for packaging; each pallet piles up 60 sacks of 18 kg of taro. Implications. The traceability model for the Mexican taro could be adapted to the traditional way of production in Mexico to increase competitiveness. Conclusions. The shipping label contains scarce information about the origin of the product. Links of the supply chain were identified and a traceability model for taro is proposed for first time.