Juan-Pablo Hernandez

El objetivo de esta investigación fue el de evaluar la resiliencia socioecológica de las chinampas en Xochimilco, México, mediante el uso del marco MESMIS, con el fin de identificar factores clave que contribuyen a su sostenibilidad. Se analizaron 51 indicadores agrupados en tres dimensiones: socio-política, económica y agroambiental. Los datos se recolectaron en dos temporadas (septiembre de 2022 y febrero de 2023) en tres zonas: Olintlalli, Granja Apampilco y Chinampas en Movimiento. Los resultados mostraron variaciones estacionales importantes. Indicadores como el desarrollo turístico agroecológico alcanzaron valores altos en septiembre y muy bajos en febrero, mientras que el uso de energías renovables mostró la tendencia opuesta. También se evidenció una persistente desigualdad en roles de género, con valores bajos en todas las zonas. En contraste, indicadores como la autosuficiencia en insumos y el acceso a programas comunitarios obtuvieron valores altos, reflejando la importancia del apoyo institucional en la resiliencia de estos sistemas. El análisis de componentes principales (PCA) reveló que la variabilidad estuvo explicada principalmente por el primer componente en ambas temporadas, reflejando las características únicas de cada zona. Esto demustra la necesidad de fortalecer prácticas sostenibles y el apoyo comunitario para preservar la integridad de las chinampas frente a desafíos contemporáneos.

Salinity is a factor that negatively affects the physiology of most plants, even placing food security at risk when it affects plants grown for food. This review provides an overview of the use of plant growth-promoting bacteria (PGPB) as a strategy for enhancing crop growth under salt stress, aiming to provide a sustainable solution for this environmental problem. Salinity causes morphophysiological and biochemical alterations in plants due to osmotic and ionic stress. Plants have different response mechanisms that allow them to survive and, in some cases, tolerate salinity. Various mitigation strategies have been evaluated, such as the use of plant hormones, fertilizers, nanofertilizers, silicon, antioxidants, tolerant genotypes, and inoculation with microorganisms, among others. Among the organisms used for inoculation, PGPB are of particular interest. PGPB, with the capacity to tolerate salinity conditions, can enhance germination, seedling vigor, root and shoot growth, and chlorophyll content in plants, in addition to other positive impacts. The mechanisms of action of PGPBs have been extensively studied and used to improve the quality of commercial crops and to produce bioinoculants. The study of these microorganisms is ongoing; more knowledge is needed on the mechanisms of action of the bacteria, the mechanisms of colonization, and the genes involved in the mechanisms of promotion and colonization. Additionally, it is necessary to expand knowledge of the most efficient ways to use these organisms in crops of commercial and environmental interest.

Due to the effects generated by the use of chemical herbicides, there is a need to seek more environmentally friendly ways to combat weeds. The allelopathic effect of Campomanesia lineatifolia seed extract on weed germination has been studied; however, information is still lacking regarding the components responsible for the allelopathic effect of the extract. Therefore, the objective of this study was to evaluate the allelopathic activity of the dichloromethane fraction of C. lineatifolia extract on the germination of Rumex crispus and Amaranthus hybridus. To achieve this, a hydroalcoholic extract of the seeds of C. lineatifolia was prepared and subsequently fractionated through sequential extraction with dichloromethane. The concentrations used in the germination tests were 0, 100, 300, and 600 mg L-1. The percentage of germination (PG), mean germination speed (MGS), mean germination time (MGT), and seed viability were assessed. In R. crispus, low concentrations (100 and 300 mg L-1) favored germination, reaching PG values of 75.5 and 64.5%, respectively. However, the highest concentration (600 mg L-1) significantly inhibited germination (77% inhibition). In the case of A. hybridus, all treatments with concentrations of the dichloromethane fraction inhibited germination compared to the 0 mg L-1 treatment, with the inhibition being most pronounced at 600 mg L-1 (98.5% inhibition). Furthermore, the MGS decreased as concentrations increased in both species, while the MGT increased in A. hybridus with higher concentrations. In conclusion, the dichloromethane fraction of the C. lineatifolia extract exhibits allelopathic activity, which can be either positive or negative depending on the species to which it is applied and the concentrations used.

Las chinampas de Xochimilco enfrentan la amenaza de la salinización del suelo, un desafío que refleja la compleja relación entre los aspectos socioecológicos. Estas tierras, emblemáticas por su historia y cultura, representan un sistema interdependiente donde prácticas agrícolas tradicionales interactúan con el entorno natural. La salinización, síntoma de desequilibrios, afecta la productividad agrícola y la vida de las comunidades locales. La solución radica en un enfoque holístico que incluye el uso de prácticas biotecnológicas para la recuperación de los suelos, la gestión del agua, la restauración de la vegetación y el turismo responsable. La participación de las comunidades y la conservación cultural son esenciales. Las chinampas nos recuerdan que la coexistencia armoniosa entre humanos y naturaleza es clave para la sostenibilidad.

This study explores how hydroalcoholic extracts of Campomanesia lineatifolia R. and P. seeds affect the germination and viability of seeds from two weeds, Rumex crispus and Amaranthus hybridus. The phenolic compounds were initially characterized using ultra-high-performance liquid chromatography. In seeds sown in Petri dishes, four concentrations of hydroalcoholic extracts (0%, 3%, 6%, and 9% w/v) were used for single and continuous applications. The mean germination speed, mean germination time, germination percentage, and seed viability were evaluated. Epigallocatechin gallate, quercetin-3-glucoside, epicatechin gallate, ursolic acid, epigallocatechin, and trans-cinnamic acid were the main compounds discovered in that order. Notably, while the germination percentages of both species were reduced with a single application (38.5% for R. crispus and 52% for A. hybridus), they were reduced by 76.2% and 58.34% with a continuous application, respectively. A delay in germination was also observed, which produced changes in germination speed throughout the experiment. With a 9% application, the number of nonviable seeds of R. crispus increased by 40.53%, whereas in A. hybridus, viability decreased by at least 70.8%. Overall, the phenolic compounds in C. lineatifolia extract are thought to inhibit the germination process of the evaluated species.

Stress due to waterlogging is considered an abiotic factor that negatively affects crop production, which, together with the excessive fertilization of crops, reduces cost-effectiveness and generates the need to create sustainable alternatives economically and environmentally. The effect of inoculation with Azospirillum brasilense on the physiology of the Raphanus sativus var. Crimson Giant subjected to waterlogging, was evaluated. Stomatal conductance, chlorophyll concentration and chlorophyll a fluorescence were analyzed to establish this effect, corroborating the beneficial effect of inoculation with A. brasilense in radish under waterlogging stress. The stomatal conductance of inoculated and waterlogged treatments presented the same values as the control plants, and photosystem II efficiency was favored in inoculated and waterlogged treatments (0.6 Fv/Fm) compared to non-inoculated and waterlogged treatments (0.3 Fv/Fm). The results suggested that this increased efficiency was due to the preservation of photosynthetic pigments in the tissues, allowing the preservation of stomatal conductance and a reduction in the amount of energy dissipated in the form of heat (fluorescence) due to inoculation with A. brasilense. Therefore, plant growth-promoting bacteria are responsible for activating and improving some physiological mechanisms of the plant.