ABSTRACT Sisal (Agave sisalana Perrine), a crucial natural fiber source, exhibits varying yields in China’s Guangdong and Guangxi regions. This groundbreaking study sampled soil and sisal leaves from these production hubs to explore the interplay among soil pH, enzyme activity, microorganisms, and sisal nutrition. Using PCR and high-throughput sequencing, results indicate Guangdong’s soil is mildly acidic, contrasting with Guangxi’s neutral to slightly alkaline soil. Both regions show a robust correlation between soil pH and nutrient availability (organic matter, P, K). Enhanced soil enzyme activity is observed at higher pH levels (6.09, 7.39). Dominant bacterial phyla Acidobacteria, Proteobacteria, and Actinobacteria peak at pH 7.39, 6.09, and 5.41, respectively. Fungal phyla Ascomycota, Basidiomycota, and Mortierellomycota thrive at pH 4.23, 7.39, and 6.48. Sisal leaves display optimal nutrient levels at specific pHs: N, P, and K at pH 6.09; Ca at pH 7.39; Mg at pH 6.48. Functional predictions reveal fungal abundance varies with pH, while bacterial functions like metabolism, disease resistance, and environmental adaptation are bolstered in Guangxi’s alkaline soils compared to Guangdong’s acidic ones. These findings provide a scientific basis for optimizing sisal cultivation management.

Resumen: Los hongos micorrícicos arbusculares (HMA) y los endófitos septados oscuros (DSEF) tienen tal influencia en el desarrollo de las plantas y en las características edafológicas y nutrientes disponibles en el suelo, que cambios en estas comunidades pueden impulsar modificaciones en las variables bióticas y abióticas de un ecosistema, demostrando la sinergia entre especies. Dada su relevancia, el objetivo de este trabajo fue determinar el estado de colonización en las raíces de tres especies herbáceas representativas del sotobosque de una comunidad de Abies religiosa (Kunth Schltdl. et Cham.) y Pinus harwegii (Lindl), y contrastar la coexistencia de colonizadores en tres escenarios de conservación-perturbación que ejemplifican las situaciones de vulnerabilidad de un ecosistema forestal. Se constata una interacción tripartita AMF-HESO-planta por la aparición de hifas coenocíticas, vesículas, hifas septadas, células moniliformes y esclerocios. Los valores de micorrización arbuscular superan el 50% y son superiores a los encontrados para los endófitos (15.7-64.5%). La colonización de ambos tipos de hongos, como la esporulación de AMF (687 esporas 50 g-1 de suelo en la zona reforestada), parece estar relacionada con las condiciones microclimáticas derivadas del uso del suelo. Las variables edafológicas que permiten inferir el comportamiento de la colonización corresponden principalmente al fósforo disponible, calcio, pH, materia orgánica y capacidad de intercambio catiónico. Se concluye que las propiedades del suelo, su uso y el tipo de plantas son determinantes en el establecimiento de las comunidades fúngicas. Sin embargo, son necesarios más estudios sobre la interacción HESO-planta.

Summary: Arbuscular mycorrhizal fungi (AMF) and dark septate endophytes (DSEF) have such an influence on plant development and on the edaphological characteristics and nutrients available in the soil that changes in these communities can drive modifications in the biotic and abiotic variables of an ecosystem, demonstrating the synergetic between species. Given its relevance, the objective of this work was to determine the status of colonization in the roots of three representative herbaceous species of the understory of a community of Abies religiosa (Kunth Schltdl. et Cham.) and Pinus harwegii (Lindl), and to contrast the coexistence of colonizers in three conservation-disturbance scenarios that exemplify the vulnerability situations of a forest ecosystem. A tripartite AMF-HESO-plant interaction is reported by the occurrence of coenocytic hyphae, vesicles, septate hyphae, moniliform cells, and sclerotia. The values of arbuscular mycorrhization exceed 50% and are higher than those found for endophytes (15.7-64.5%). The colonization of both types of fungi, such as AMF sporulation (687 spores 50 g-1 soil in the reforested area), seems to be related to the microclimatic conditions resulting from soil use. The edaphological variables that allow inferring the colonization behavior correspond mainly to available phosphorus, calcium, pH, organic matter, and cation exchange capacity. It is concluded that soil properties, its use, and the type of plants are determinant in the establishment of fungal communities. However, more studies on HESO-plant interaction are needed.

A developing trend in stormwater treatment and management is the use of green technologies. Plant biofilters have been gaining increasing use in support of green technology objectives. This technical note reports on the development and preliminary testing of a laboratory-scale plant biofilter prototype for ammonia removal using a South African native plant species (Juncus effusus). The prototype design was based on a conceptual model for nitrogen fixation, plant uptake, bacterial nitrification and soil sorption. Additionally, a plug compartment was incorporated into the design to simulate plug flow as part of the conceptual model. Biofilter models with and without inoculated bacteria were compared. Ammonia reduction, nitrite and nitrate formation were observed. Results showed that the inoculated plant biofilter performed best, with an average of 61% reduction in ammonia within the filter compared to 15% in the normal plant biofilter. The incorporation of a plug compartment aided in slowing down the ammonia infiltration rate, increasing the retention time, and allowing for nitrification to occur.

ABSTRACT Soil salinization, a rising issue globally, is a negative effect of the ever-changing climate, which has drawn attention to, and exacerbated problems related to soil degradation and the decline in wetland rice (Oryza sativa L.) production, leading to an unstable national economy. The use of rhizosphere inhabiting microorganisms (plant growth-promoting rhizobacteria, PGPR) is a viable method for boosting agricultural production on saline soils and reduce salt stress in rice crops. The objective of this study was to support the development of rice under salt stress by using a consortium of bacterial strains. ‘Pokkali’ rice plants inoculated with single Bacillus tequilensis and B. aryabhattai isolates were compared with consortium and non-inoculated plants while salinity was increased and by irrigation with tap water (control), 30 mM (5 dS m-1) and 60 mM (10 dS m-1) NaCl. The present study exhibited that inoculation of a mixed inoculum at 5 dS m-1 resulted in significantly higher dry weight of the shoots and roots of seedlings (9.29 and 1.24 g, respectively) which was due to the increased SPAD value, proline content (7.55 µmol g-1 FW), and antioxidant enzyme activity in the inoculated plants. The higher accumulation of osmoprotectants such as proline supported Na+ ion reduction and antioxidant enzymes such as ascorbate peroxidase and reduced polyphenol oxidase content protect against higher cellular damage, eventually leading to increase plant growth performance in saline soil. This study demonstrates some positive effects of the locally isolated salt tolerant consortium PGPR strains on the growth of rice plants under salt stress conditions.

Abstract Phytophthora capsici is an aggressive pathogen in escabeche pepper on the Peruvian coast. Root rot has a strong correlation with humidity and environment. Disease behavior was evaluated epidemiologically using spatiotemporal variables. Severity was evaluated according to the advance of the secondary symptom according to grades 1 to 5. Then, coordinates of each plant were established by photogrammetric survey of a field with 1705 escabeche pepper plants. For temporal analysis, severity was adjusted to an exponential model (R2 = 0.909) and incidence to a Gompertz model (R2 = 0.921) that detected an initial delay of the disease due to temperature. For the spatial analysis, the Global Moran Index (Ii) showed a high spatial dependence of the disease reaching a peak of 0.4 and 0.7 for severity and incidence, respectively. Also, heat maps related to the Local Ii were generated from which an initial source of infestation was determined where the furrow irrigation started in random infestations. Then, the infestation spots were settled in areas of surface water accumulation. Also, rhizosphere samples were collected per plant by degree of severity on V8 or CMA whit PARB and PDA-A selective medium. As a result, significant differences were obtained between grade 1, grade 2, 3, 4 and grade 5. In addition, the effect on yield was significant for plants with grade 4 and 5 with respect to fruit weight (22.3 and 18.5g/fruit) and weight per plant (509.5 and 371.8g/plant), respectively.

Resumen Antecedentes: La supervivencia de cactus columnares en desiertos ocurre principalmente bajo plantas nodrizas, debido a mejores condiciones para germinar y establecerse (mayor humedad y concentración de nutrientes). Empero, interacciones como la asociación entre hongos micorrizógenos arbusculares (HMA) y raíces continua relativamente inexplorada. Evaluamos el estado micorrícico y propiedades del suelo rizosférico de cuatro especies de cactus columnares creciendo tanto debajo como fuera de su nodriza. Hipótesis: Se ha relacionado el mejoramiento de propiedades del suelo bajo la nodriza con la abundancia de HMA. Por lo tanto, plantas facilitadas mostrarán más estructuras de HMA y de micorrización de raíces, comparado con las mismas especies creciendo fuera de la nodriza. Especies estudiadas: Nodriza: Olneya tesota, facilitadas: Carnegiea gigantea, Pachycereus pringlei, Pavhycereus schottii, Stenocereus thurberi. Sitio y años de estudio: Subdivisión de la Costa Central del Golfo del Desierto Sonorense, Sonora, México, octubre de 2020. Métodos: Se recolectaron raíces de cactus y suelo rizosférico debajo y fuera de la nodriza. En raíces teñidas se determinó: colonización micorrízica (CM), pelos radicales (PR), densidad visual (DV) y número de esporas (NE). Se analizaron propiedades fisicoquímicas del suelo. Resultados: Valores de CM, DV, NE, materia orgánica, nitrato y fósforo total y asimilable fueron mayores bajo la nodriza en comparación con áreas desnudas. Conclusiones: Se confirma la hipótesis planteada y se reafirma el conocimiento previo sobre la calidad del suelo bajo nodrizas, sugiriendo que los HMA juegan un papel importante en la facilitación de cactus bajo las plantas nodrizas, y que estas últimas influencian la formación de HMA.

Abstract Background: Columnar cacti survival in deserts occurs mainly under nurse plants, due to better conditions for germination and establishment, as greater humidity, and nutrient concentration. However, interactions like the association between arbuscular mycorrhizal fungi (AMF) and roots remain relatively unexplored. We evaluated the mycorrhizal status and soil rhizosphere properties of four columnar cacti species growing both under and outside their nurse plant. Hypotheses: Soil properties improvement under nurse plants has been correlated with the abundance of AMF. Therefore, a greater number of AMF structures and roots mycorrhization would be in facilitated plants, compared to the same species growing outside the nurse. Studied species: Nurse plant: Olneya tesota, facilitated species: Carnegiea gigantea, Pachycereus pringlei, Pachycereus schottii, and Stenocereus thurberi. Study site and dates: Central Gulf Coast subdivision of the Sonoran Desert, Sonora, Mexico; October 2020. Methods: Cacti roots and soil rhizosphere were collected under and outside the nurse plant. Roots were stained, and mycorrhizal colonization (MC), hairy roots (HR), visual density (VD), and number of spores were determined. Physicochemical soil properties were analyzed. Results: Values of MC, VD, spore number, organic matter (OM), nitrate, and total and assimilable phosphorous were higher under the nurse compared to bare areas. Conclusions: The hypothesis that mycorrhization parameters are greater in roots of cacti growing under the nurse was confirmed, besides previous knowledge about soil quality under nurse plants, suggesting that AMF play a significant role in the cacti facilitation process under nurses plants, and that nurse plant plays a significant role in AMF formation.

Resumen Antecedentes: Existen reportes de que los Hongos Micorrizógenos Arbusculares (HMA) incrementan la producción de metabolitos secundarios en plantas medicinales. El género Croton ha sido poco estudiado en este aspecto. C. draco es una especie etnomedicinal, conocer la relación y naturaleza de los HMA, puede contribuir a obtener plantas en cultivo con mayor calidad y cantidad de metabolitos secundarios. Preguntas: ¿Las raíces de C. draco pueden ser colonizadas por HMA? ¿Qué especies de HMA se encuentran en la rizósfera de C. draco? ¿La diversidad de especies de HMA varía dependiendo del ambiente? Sitios de estudio y periodo de investigación: El estudio se hizo en tres localidades del estado de Veracruz, en el año 2019. Métodos: Raíces terciarias de árboles adultos se procesaron y observaron al microscopio compuesto buscando esporas, hifas y arbúsculos de HMA. La diversidad y densidad esporas en la rizosfera de C. draco, se determinó en muestras de suelo, comparando tres sitios de estudio. Los datos se normalizaron y se hicieron pruebas paramétricas. Resultados: Se observaron esporas, hifas y arbúsculos en las raíces de C. draco. La abundancia de esporas y diversidad de HMA fue diferente entre los sitios evaluados. Con base en la morfología de las esporas se reconocieron 14 taxones, de los cuales, solo dos están presentes en los tres sitios. Conclusión: C. draco presentó en sus raíces estructuras propias de los HMA. Basado en los resultados concluimos que las condiciones ambientales influyen en la abundancia de esporas y en la diversidad de especies de HMA.

Abstract Background: There are reports that Arbuscular Mycorrhizal Fungi (AMF) increase the production of secondary metabolites in medicinal plants. The Croton genus has not been widely studied in this aspect. C. draco is an ethnomedicinal species, knowing the relationship and nature of AMF can contribute to obtaining plants in crops with a good quality and quantity of secondary metabolites. Questions: Can the roots of C. draco be colonized by AMF? What type of AMF species can be found in the rhizosphere of C. draco? Could the diversity of AMF species vary depending on the environment? Study sites and dates: The study was carried out in three locations in the state of Veracruz, in 2019. Methods: Tertiary roots of adult trees were processed and observed under a compound microscope looking for AMF spores, hyphae and arbuscules. The diversity and density of spores in the rhizosphere of C. draco was determined in soil samples, comparing the two sites. Data were normalized and parametric tests were performed. Results: Spores, hyphae and arbuscules were observed on the roots of C. draco. The abundance of spores and AMF diversity was different between the evaluated sites. Based on the morphology of the spores, fourteen taxa were recognized, and among them, only two were found in the three sites. Conclusions: C. draco showed structures typical of AMF in its roots. Based on these results we can say that environmental conditions influence the abundance of spores and the diversity of AMF species.

SUMMARY: The main objective of this study is to isolate, select, and determine the vegetal growth-promoting capacity of rhizobacteria of Algarrobo trees and stumps at the seed and laboratory levels, with the purpose of selecting strains that could be used for reforestation of dry forest in Piura. Two composite samples of rhizosphere soil were obtained: one from stumps (felled trees) and the other from algarrobo trees, of which 16 and 18 bacterial strains were isolated, respectively. Measurements at a laboratory level included free nitrogen fixation, indolacetic acid, cellulolytic, and phosphate solubilizing production capacity. For each soil sample, five strains were selected with complementary (not antagonistic) properties to make an inoculating liquid and evaluate its effect on seed growth: 53 % for stumps, 37 % for trees, and 34 % for control (water). Inoculant strains were molecularly identified as Actinomycetes and other strains as Bacillus sp., B. paramycoides, B. wiedmannii, B. thuringiensis, and B. subtilis. Therefore, it was demonstrated that the rhizosphere of a dry forest carob, whether as a tree or stump, is an important source of rhizobacteria with plant-promoting capacity, which can be used to reforest the dry forest.

RESUMEN: El objetivo principal de este estudio es aislar, seleccionar y determinar la capacidad promotora del crecimiento vegetal de rizobacterias en el tocón y el árbol de algarrobo a nivel de laboratorio y de semillas, con el fin de poder tener un banco de cepas que pueda usarse para la reforestación del bosque seco en Piura. Se obtuvieron dos muestras compuestas de suelo rizosférico: una de tocones (árboles talados) y otra de árboles de algarrobo, de las cuales se aislaron 16 y 18 cepas bacterianas, respectivamente. A nivel de laboratorio, se evaluó la capacidad de fijar nitrógeno libre y producir ácido indolacético, actividad celulolítica y solubilizadora de fosfatos. Por cada muestra de suelo se escogieron cinco cepas con propiedades no antagonistas sino más bien complementarias entre sí, para hacer un inoculante líquido y evaluar su efecto en la germinación de semillas. Se encontró porcentajes de germinación de 53 % para tocones, 37 % para árboles y 34 % para el control (agua). Las cepas de los inoculantes fueron identificadas molecularmente como un Actinomicetos y otras cepas de Bacillus sp., B. paramycoides, B. wiedmannii, B. thuringiensis y B. subtilis. Por lo tanto, se demostró que la rizosfera de algarrobo de bosque seco, ya sea como árbol o tocón, es una fuente importante de rizobacterias con capacidad promotora vegetal, que puede ser usada para reforestar el bosque seco.

Abstract Plant growth-promoting bacteria (PGPB) that inhabit root rhizosphere of plants are of great agricultural importance due to their ability to produce phytohormones during root colonization. These phytohormones produce physiological changes in the plant that favor a greater absorption of nutrients, promote growth and increase production. This study analyzed the effect of inoculation of two of these bacteria, Azospirillum sp. and Pseudomonas fluorescens, under field conditions representative of the Andean Highlands. The experiment was carried out using flour corn seed of the INIAP-101 variety in a randomized complete block design with six repetitions. The treatments corresponded to: T1 (Azospirillum sp.), T2 (P. fluorescens), T3 (Azospirillum sp. and P. fluorescens), T4 (control, conventional chemical fertilization) and T5 (absolute control). The application of these bacteria significantly increased (p<0.05) the root length, the diameter of the cob, and the yield of fresh corn (“elotes” or “choclos”). The combined inoculation of these bacteria (T3) obtained the highest yield, with 19.70 t ha−1 of fresh corn; while the chemical control and the absolute control got 17.12 and 13.58 t ha−1 of fresh corn, respectively. The economic analysis of T3 reported a benefit/cost of 1.35, which indicates that the synergism of these two bacteria could be a sustainable strategy to improve yields and reduce the use of chemical fertilizers for corn production in the Andean region.

Resumen Las bacterias benéficas que habitan la rizósfera de las plantas son de gran interés agrícola debido a su capacidad para producir fitohormonas durante la colonización radicular. Estas fitohormonas producen cambios fisiológicos en la planta que favorecen una mayor absorción de nutrientes que provocan un rápido crecimiento vegetativo y una mayor producción. Esta investigación tuvo como objetivo evaluar el efecto de la inoculación de dos de estas bacterias, Azospirillum sp. y Pseudomonas fluorescens en el cultivo de maíz harinoso bajo condiciones de campo típicas de la región alto andina. El experimento se realizó utilizando semilla de maíz harinoso de la variedad INIAP-101 con un diseño de bloques completos al azar y seis repeticiones. Los tratamientos correspondieron a: T1 (Azospirillum sp.), T2 (P. fluorescens), T3 (Azospirillum sp. y P. fluorescens), T4 (testigo con fertilización química convencional) y T5 (testigo absoluto). La aplicación de estas bacterias incrementó de manera significativa (p<0,05) la longitud de raíz, el diámetro de la mazorca y el rendimiento del maíz tierno (elotes o choclos). La inoculación combinada de estas bacterias (T3) obtuvo el mayor rendimiento con 19,70 t ha−1 de choclos, mientras que el testigo químico y el testigo absoluto obtuvieron 17,12 y 13,58 t ha−1 de choclos, respectivamente. El análisis económico de T3 reportó un coste/beneficio de 1,35, lo cual indicó que el sinergismo de estos dos géneros podría ser una estrategia sostenible para mejorar los rendimientos y reducir el uso de fertilizantes químicos en el cultivo de maíz de la región Andina.

RESUMEN El objetivo del trabajo fue determinar el efecto de la fertilización nitrogenada sobre la respiración de la población microbiana asociada a la rizosfera de Saccharum officinarum L. En experimento de larga duración, Umln_6, plantado con Saccharum officinarum L., y seis niveles de nitrógeno, ubicado en la provincia Santiago de Cuba. Se determinó la respiración microbiana, mediante valoraciones químicas en medio cerrado, el rendimiento agrícola y la interacción con variables químicas y meteorológicas del ecosistema. Los datos se procesaron por análisis de varianza factorial, modelo AMMI y ACP. La variable respiratoria tuvo un comportamiento diferencial para los niveles de N aplicados y la fenología del cultivo, además de la influencia de estos factores sobre las propiedades químicas del suelo que alcanza su valor máximo con una dosis promedio de N, de 100.6 kg.ha-1. Los resultados indican que la evaluación de las interacciones caña de azúcar-microorganismos del suelo puede ser útil para un mejor manejo de la fertilización nitrogenada.

ABSTRACT The objective of this work was to determine the effect of nitrogen fertilization on the respiration of the microbial population associated with the rhizosphere of Saccharum officinarum L. The quantities of soil microorganisms as an expression of its quality, allow establishing relationships with its chemical properties, by determining microbial respiration. In a long-term experiment, Umln_6, planted with Saccharum officinarum L., and six levels of nitrogen, planted in Santiago of Cuba province. The microbial respiration was determined through chemical assessments in a closed environment, agricultural yield and the interaction with chemical and meteorological variables of the ecosystem. The data were processed by factorial variance analysis, AMMI model and PCA. The respiratory variable had a differential behavior for the levels of N applied and the phenology of the crop, in addition to the influence of these factors on the chemical properties of the soil that reaches its maximum value with an average dose of N, of 100.6 kg.ha-1. The results indicate that the evaluation of sugarcane-soil microorganism interactions can be useful for better management of nitrogen fertilization.

ABSTRACT Sugarcane-duck symbiosis (SDS) is an ecological breeding production method wherein meat ducks are released in sugarcane (Saccharum officinarum L.) fields during the middle and late stages of sugarcane growth. The effects of SDS on sugarcane rhizobacterial diversity remain poorly understood. We conducted field experiments with sugarcane monoculture (SC) and SDS and performed genetic analyses on the rhizobacterial communities based on 16S rRNA across different growth stages of sugarcane. The effects of soil physicochemical factors on the bacterial community structure were analyzed via redundancy analysis. We found that soil organic matter (SOM), total N (TN), nitrate N (NN), and ammonium N (AN) contents of sugarcane rhizosphere soils increased during different growth periods in SDS. During the perennial root stages, the Shannon-, Ace-, and Chao1 indices increased, whereas the available P (AP) content decreased. The soil pH was more balanced and its effect on the soil bacterial community was insignificant. The dominant sugarcane rhizosphere flora were Actinobacteria, Proteobacteria, Chloroflexi, Acidobacteria, Firmicutes, norank_f__norank_o__Gaiellales, Sphingomonas, norank_f__Roseiflexaceae, Bacillus, and norank_f__Xanthobacteraceae, but with significant inter-annual variations. Redundancy analysis showed that SOM, TN, NN, AN, AP, catalase (CAT) and invertase (INV) activity were closely associated with the diversity of the soil bacterial communities, and TN and INV activity were the main drivers of sugarcane rhizobacterial communities in the SDS groups. In conclusion, SDS improves the fertilizer supply capacity and soil quality of sugarcane soils by regulating major soil nutrient content, available nutrients, and microbial diversity. This study provides a theoretical basis for scientifically managing SDS and the screening of biocontrol bacteria.

RESUMEN La caoba y el cedro son especies nativas de América Tropical y se consideran maderas preciosas tropicales más valiosas del mundo. Por lo que se han establecido plantaciones forestales a escala comercial, dándole un manejo silvícola sustentable, siendo la fertilización una de las prácticas más importantes. El objetivo de este trabajo fue evaluar el efecto de cuatro dosis de fertilización sobre el crecimiento de caoba y cedro en fase temprana en un suelo ácido de sabana, así como determinar la demanda nutrimental de NPK de cada especie. En el experimento se probaron ocho tratamientos de fertilización en las dos especies. Las variables estudiadas fueron altura total y diámetro del tallo, realizándose mediciones durante 10 meses. Para estimar la demanda nutrimental, se muestrearon cuatro árboles completos; y se determinó su concentración NPK en cada tejido (hoja, tallo y raíz). Los resultados muestran que el cedro presentó mayor crecimiento en altura y diámetro. La variable altura en la especie cedro, fue la que mostró diferencias estadísticas significativas, siendo el tratamiento 17-17-60 con las cantidades de 35 y 50 g con un incremento de 177 cm. La cantidad de nutriente de NPK que demandan ambas especies presentan una relación en el orden siguiente N>K>P. La mayor extracción de N, P y K la realiza el tallo y en menor cantidad la raíz. Y en el caso de la mayor concentración de nutriente se encuentra en las hojas. El cedro mostró mayor demanda nutrimental y mejor exploración de la rizósfera que la caoba.

ABSTRACT Mahogany and cedar are native species of tropical America and are considered the most valuable tropical hardwoods in the world. Therefore, forest plantations have been established on a commercial scale, giving them a sustainable silvicultural management, being fertilization one of the most important practices. The objective of this work was to evaluate the effect of four doses of fertilization on the growth of early-stage mahogany and cedar in an acid savanna soil, as well as to determine the NPK nutrient demand of each species. Eight fertilization treatments were tested on the two species. The variables studied were total height and stem diameter, and measurements were taken during 10 months. To estimate nutrient demand, four complete trees were sampled and NPK concentration was determined in each tissue (leaf, stem and root). The results show that cedar presented greater growth in height and diameter. In the height variable in the cedar species, it was the one that showed significant statistical differences, being the treatment 17-17-60 with the amounts of 35 and 50 g with an increase of 177 cm. The amount of NPK nutrient demanded by both species presented a relationship in the following order N>K>P. The greatest extraction of N, P and K is carried out by the stem and to a lesser extent by the root. And in the case of the highest concentration of nutrient is found in the leaves. Cedar showed higher nutrient demand and better exploration of the rhizosphere tan mahogany.

ABSTRACT Cotton (Gossypium hirsutum L.) is economically important in Xinjiang, China, for many years; Verticillium wilt, arid climate, and soil salinization reduce cotton production, which has inhibited development of the cotton economy. Thus, creating a microbial agent specifically for cotton to resisting environmental stress is crucial. In this study, water dispersible granules strains (Bacillus tequilensis C-9 and B. sphingosporium A1) were screened for antagonistic bacteria of Verticillium dahliae from the rhizosphere soil of Ferula sinkiangensis K.M. Shen, and screened for carrier and auxiliary that could enhance the survival of strains A1+C-9. To test the efficacy and practicality of the water dispersible granules, their growth-promoting effect was examined. Meanwhile, bursts of reactive oxygen species and changes in the physiological indicators related to cotton growth were detected after the application of these granules to cotton that had been subjected to biotic and abiotic stresses to study the ability of the water dispersible granules to induce immunity in cotton. It was found that the treated group could increase the above-ground and below-ground fresh weight of cotton by 20.06% and 22.71% relative to the control group, and the biocontrol effect on cotton was increased by 46.55%. In salt and drought stress, catalase activity could be increased by 14.61% and 15.52%, respectively, relative to the control group. Comprehensive analyses showed that the application of water dispersible granules that contained A1+C-9 helped the cotton to grow and develop, inhibited V. dahliae from infecting cotton plants, reduced the damage from drought and salt stress, and increased the resilience of cotton to stress.

RESUMEN La fitorremediación es una alternativa para limpiar suelos contaminados utilizando plantas y sus microorganismos asociados. El presente trabajo evaluó la fitotoxicidad y la fitorremediación de un suelo contaminado con gasolina por plantas de girasol (Helianthus annuus L.) asistida con bacterias rizosféricas nativas. Esta investigación contempló tres fases experimentales partiendo de un suelo artificialmente contaminado con gasolina. La primera fase evaluó la germinación de semillas de girasol y su crecimiento en un suelo contaminado (0, 200, 400, 800, 1600, 2400 y 3200 mg/kg), observándose la germinación y la tolerancia de las plántulas en todas las concentraciones de gasolina, a los 20 días. En la segunda fase se aislaron bacterias totales del suelo contaminado y se caracterizaron mediante pruebas bioquímicas relacionadas con el crecimiento vegetal y se identificaron molecularmente. La gasolina inhibió el crecimiento bacteriano, y se seleccionaron 10 cepas con capacidad promotora del crecimiento vegetal, sobresaliendo los géneros Bacillus, Streptomyces, Pseudomonas, Priestia, Massilia y Sphingobium. La tercera fase consistió en un bioensayo de fitorremediación del suelo contaminado (0, 1600 y 3200 mg/kg) inoculando plantas con las 10 bacterias aisladas de la fase 2, aplicadas en consorcio. A los 60 días, a pesar de no influir en el crecimiento vegetal, las bacterias disminuyeron significativamente la presencia del contaminante en el suelo (~50 % remoción). La inoculación de girasol con bacterias nativas es una alternativa para reducir la contaminación de gasolina en el suelo.

ABSTRACT Phytoremediation is an alternative for cleaning contaminated soils using plants and associative microorganisms. This study evaluated the phytotoxicity and phytoremediation of a gasoline-contaminated soil by sunflower plants (Helianthus annuus L.) assisted with native rhizosphere bacteria. The research consisted of three experimental phases based on artificially gasoline-contaminated soil. The first phase evaluated the seed germination and seedling emergence under contaminated soil (0, 200, 400, 800, 1600, 2400, and 3200 mg/kg); for 20 days, seed germination and seedling tolerance were achieved at all concentrations. The second phase of the study isolated bacteria from the contaminated soil, characterized by biochemical tests related to plant growth promotion, and molecularly identified. Gasoline inhibited bacterial growth, and ten potential plant growth-promoting bacteria were isolated, which belonged to Bacillus, Streptomyces, Pseudomonas, Priestia, Massilia, and Sphingobium. The third phase consisted of a bioassay for phytoremediation of gasoline-contaminated soil (0, 1600, and 3200 mg/kg) by inoculating sunflower plants with the ten bacteria obtained from phase 2 as a bacterial consortium. After 60 days, despite not having influenced plant growth, bacterial inoculation significantly diminished the soil contaminant (~50 % removal). The inoculation of the sunflower plants with ten native bacteria reduced the gasoline-contamination in soil.

ABSTRACT The fungal microbiota associated with the roots and rhizosphere of plants represents a significant source of biocontrol agents against the root-knot nematode Meloidogyne spp. While some fungal genera have been studied extensively, others require more attention in terms of their identity and mechanisms of action against plant parasitic nematodes. Thus, the aim of this research was to demonstrate the in vitro and in vivo biocontrol potential of fungi isolated from the root and rhizosphere of guava plants against the root-knot nematode Meloidogyne incognita. We isolated four fungi (C5, C6, C7, and C10) from the root and rhizosphere of guava plants using the serial dilution method. These fungi were purified on potato dextrose agar and evaluated in vitro to assess their ability to parasitize M. incognita eggs and juveniles. Subsequently, the fungi were assessed for M. incognita control under nursery conditions in guava plants. The identity of the fungi with parasitic capacity and biocontrol potential was confirmed by amplifying and sequencing the ITS region, followed by Bayesian inference analysis. Results showed that the fungi corresponded to Talaromyces sayulitensis (C5), Myrothecium sp. (C6), Penicillium shearii (C7), and Beauveria bassiana (C10). Parasitism of M. incognita eggs was confirmed for all fungi, parasitism of juveniles occurred with T. sayulitensis (C5) and B. bassiana (C10). In guava seedlings treated with fungal isolates, a significant reduction in the number of eggs, juveniles, and nodules per gram of root was achieved. The biocontrol potential against M. incognita in guava seedlings was confirmed for different fungi associated with the root rhizosphere. rootknot knot spp extensively nematodes Thus C5, C5 C (C5 C6 C7 C10 method M Subsequently region analysis , sp (C6) (C7) C10. . (C10) T B isolates achieved (C C1 (C6 (C7 (C10 (C1