RESUMO: Microrganismos na rizosfera desempenham um papel importante no crescimento e saúde das plantas. Em todo o mundo, vários patógenos do solo atacam o Capsicum annuum causando danos significativos e perdas econômicas. Este estudo teve como objetivo determinar se a diversidade e composição das comunidades microbianas no solo da rizosfera de plantas de C. annuum é alterada significativamente pela murcha. Usamos o gene 16S rRNA para bactérias e a região espaçadora transcrita interna para fungos para caracterizar os microbiomas da rizosfera de plantas saudáveis e plantas com murcha. Os filos bacterianos mais abundantes foram Proteobacteria e Gemmatimonadetes, enquanto os filos fúngicos foram Ascomycota e Mucoromycota. A diversidade alfa bacteriana não mostrou diferenças significativas na riqueza e diversidade, mas mostrou uma diferença significativa na uniformidade e dominância das espécies. Táxons raros estavam presentes em condições saudáveis e murchas com abundância relativa < 1%. Em fungos, todos os estimadores avaliados apresentaram redução significativa na condição de murcha. A diversidade beta apresentou diferenças significativas na estrutura das comunidades bacterianas e fúngicas, que foram segregadas de acordo com as condições fitossanitárias. O mesmo aconteceu ao comparar a diversidade alfa e beta deste estudo baseado na agricultura orgânica com a de outros estudos baseados na agricultura convencional. Uma diferença significativa foi observada com os estimadores analisados segregando as comunidades da rizosfera dependendo do método de cultivo utilizado. Por fim, a análise de abundância diferencial não apresentou resultados significativos nas comunidades bacterianas; entretanto, nas comunidades fúngicas, os gêneros Fusarium, Thanatephorus, Rhizopus, Curvularia, Cladosporium e Alternaria foram mais abundantes na rizosfera de plantas murchas do que saudáveis. Várias espécies desses gêneros foram previamente relatadas como fitopatógenos de várias plantas, incluindo C. annuum.

ABSTRACT: Rhizosphere microorganisms play an important role in the growth and health of plants. Around the world, diverse soil-borne pathogens attack Capsicum annuum causing significant damage and economic losses. This study determined whether the diversity and composition of microbial communities in the rhizosphere soil of C. annuum plants is significantly changed by wilt disease. We used the 16S rRNA gene for bacteria and the internal transcribed spacer region for fungi to characterize the rhizosphere microbiomes of healthy and wilted plants. The most abundant bacterial phyla were Proteobacteria and Gemmatimonadetes, while the most abundant fungal phyla were Ascomycota and Mucoromycota. The bacterial α-diversity did not show significant differences in richness and diversity, but did show a significant difference in evenness and dominance of species. Rare taxa were present in both healthy and wilted conditions with relative abundances < 1%. In the fungi, all evaluated estimators showed a significant reduction in the wilted condition. The β-diversity showed significant differences in the structure of bacterial and fungal communities, which were segregated according to plant health conditions. The same occurred when comparing the alpha and beta diversity of this study based on organic agriculture with that of other studies based on conventional agriculture. We observed a significant difference with estimators analyzed by segregating rhizosphere communities depending on the farming method used. Finally, the differential abundance analysis did not show significant results in the bacterial communities; however, in the fungal communities, Fusarium, Thanatephorus, Rhizopus, Curvularia, Cladosporium, and Alternaria were more abundant in the rhizosphere of wilted than healthy plants. Species from these genera have been previously reported as phytopathogens of several plants, including C. annuum.

ABSTRACT The intensive use of highly toxic pesticides in the production of specialized horticultural crops entails environmental and social risks that can be measured through pesticide risk indicators to assess the potential negative impact of these products on ecosystems. In addition, this measurement enables the comparison of the achievements that result from the implementation of sustainable agricultural practices in terms of risk reduction due to the use of pesticides. The objective of this research was to estimate the potential environmental impact due to the use of pesticides in three melon production areas in the Comarca Lagunera. A cross-sectional descriptive study was carried out by applying a survey in 19 properties selected by non-probabilistic sampling. The Environmental Impact (EI) was evaluated using the Environmental Impact Quotient (EIQ) model, which is based on the calculation of the EIQ and the Environmental Impact Quotient in the Field (EIQF). The results show that the pesticides that contributed with the greatest environmental burden in the study areas were: Chlorothalonil (49 %), elemental sulfur (11 %) and endosulfan (10 %) in Mapimí; carbofuran (19 %), endosulfan (18 %) and carbendazim (12 %) in Matamoros-Viesca, and copper oxychloride (20 %), endosulfan (17 %) and mancozeb (17 %) in Tlahualilo. The production systems with the highest AI values were identified on intermediate (199 to 500) and late (201 to 701) sowing dates in Mapimí and late dates (132 to 383) in Matamoros-Viesca. The EIQ model allowed the identification of pesticides and production systems with the greatest negative environmental impact in the main areas of melon production in the Comarca Lagunera and provides a quantifiable scale that will allow the evaluation and comparison of future changes in the regional use of pesticides.

RESUMEN El uso intensivo de plaguicidas altamente tóxicos, en la producción de cultivos hortofrutícolas especializados, conlleva riesgos ambientales y sociales, que pueden medirse mediante indicadores de riesgo de plaguicidas, para evaluar el potencial de impacto negativo de estos productos en los ecosistemas y comparar los logros de la implementación de prácticas agrícolas sustentables, en términos de reducción de riesgos, por la utilización de plaguicidas. El objetivo de esta investigación fue estimar el potencial impacto ambiental, por uso de plaguicidas, en las tres áreas de mayor producción de melón en la Comarca Lagunera. Se realizó un estudio descriptivo transversal, mediante la aplicación de una encuesta en 19 predios, seleccionados mediante muestreo no probabilístico. El Impacto Ambiental (IA) se evaluó mediante el modelo del Cociente de Impacto Ambiental (CIA), que se basa en el cálculo del CIA y el Cociente de Impacto Ambiental en Campo (CIAC). Los resultados muestran que los plaguicidas que contribuyeron con la mayor carga ambiental en las áreas de estudio fueron: clorotalonil (49 %), azufre elemental (11 %) y endosulfan (10 %), en Mapimí; carbofuran (19 %), endosulfan (18 %) y carbendazim (12 %), en Matamoros-Viesca; y oxicloruro de cobre (20 %), endosulfan (17 %) y mancozeb (17 %), en Tlahualilo. Los sistemas de producción, con los valores del IA más altos, se identificaron en fechas de siembra intermedias (199 a 500) y tardías (201 a 701), en Mapimí, y fechas tardías (132 a 383) en MatamorosViesca. El modelo del CIA permitió identificar a los plaguicidas y los sistemas de producción con el mayor impacto ambiental negativo en las tres principales áreas de producción de melón en la Comarca Lagunera, además de proporcionar una escala cuantificable, que permitirá evaluar y comparar futuros cambios en el uso regional de plaguicidas.

Abstract: The melon (Cucumis melo L.) is one of the most important vegetables in Mexico, where the Comarca Lagunera is the region with the largest melon production. This crop is attacked by various pests and diseases that limit their production by what has been created dependence on synthetic pesticides use for their control. In order to identify the types of pesticides and their forms of use in the production of melon and analyze the toxicological profile of the most used, a cross-sectional study was conducted during the 2010 agricultural cycle through a survey on 19 plots selected by purposive sampling in major areas of producing. According to the results, 50 active ingredients (a.i.) of 26 chemical groups were used. Of total a.i. 26 % are not authorized to melon by COFEPRIS and 46 % are highly hazardous to health and the environment by PAN International. In all plots was practiced under dosing or overdosing and 95 % mixtures were used with two to six pesticides. Of the seven most used pesticides six are high health and environmental risk, they were carbofuran (68 %), endosulfan (58 %), chlorothalonil (58 %), mancozeb (53 %), imidacloprid (47 %) and methamidophos (42 %). These results show the need to encourage alternative phytosanitary control to decrease the use of synthetic pesticides, as well as promote strict regulation to oversee its proper use and banning highly hazardous pesticides.

Resumen: El melón (Cucumis melo L.) es una de las hortalizas más importantes en México, donde la Comarca Lagunera destaca como la principal región melonera. Es un cultivo atacado por diversas plagas y enfermedades que limitan su producción, por lo que su control depende del uso plaguicidas sintéticos. Con el fin de identificar los tipos de plaguicidas, sus formas de uso en la producción de melón en la Comarca Lagunera y analizar el perfil toxicológico de los plaguicidas más usados, se realizó un estudio descriptivo transversal durante el ciclo agrícola 2010 mediante una encuesta en 19 predios seleccionados por mu est reo dirigido en las principales áreas de producción. De acuerdo con los resultados, se usaron 50 ingredientes activos (i.a.) de 26 grupos químicos, el 26 % de i.a., no están autorizados para melón por la COFEPRIS y 46 % son altamente peligrosos para la salud y el ambiente según el PAN International. En todos los predios se practicó la subdosificación o sobredosificación y en 95 % se emplearon mezclas con dos a seis plaguicidas. De los siete plaguicidas más usados seis son de alto riesgo sanitario y ambiental, estos fueron carbofuran (68 %), endosulfan (58 %), clorotalonil (58 %), mancozeb (53 %), imidacloprid (47 %) y metamidofos (42 %). Estos resultados muestran la necesidad de fomentar alternativas de control fitosanitario que disminuyan el uso de plaguicidas sintéticos, así como promover una regulación estricta que vigile su uso correcto y prohiba los plaguicidas altamente peligrosos.

Three strains of Candida oleophila and their combination were evaluated for nutrient competition as a mode of action for the biocontrol of Penicillium expansum and Botrytis cinerea. C. oleophila treatments reduced germination of conidia of both pathogens when challenged on 1% 'Golden Delicious' apple juice. P. expansum conidia germination was 1x10(7) mL-1 and B. cinerea conidia germination was 5x10(5) mL-1. C. oleophila treatments lowered conidia germination from 2-7x10(4) mL-1 for P. expansum and from 1-4x10(4) for B. cinerea. C. oleophila treatments reduced conidia germination on an average of 99% for P. expansum and 96% for B. cinerea. Sugar consumption for L07 rugose was of 0.026 mg mL-1 against B. cinerea and of 0.056 mg mL¹ against P. expansum. Sugar consumption supports conidia germination reduction. P. expansum consumed 1.69 μg L-1 of proteins, while L07 rugose consumed the greatest amount with 47.95 μg L-1. B. cinerea consumed 8.95 μg L-1 and L06 consumed 36.89 μg L-1, which was statistically equal to that of L07 rugose with 27.96 μg L-1. C. oleophila strains biocontrol B. cinerea and P. expansum, in part, by nutrient competition.

Tres cepas de Candida oleophila y su combinación, se evaluaron para determinar la competencia por nutrientes, como modo de acción para el biocontrol de Penicillium expansum y Botrytis cinerea. Los tratamientos con C. oleophila redujeron la germinación de conidios de ambos patógenos, al ser enfrentadas en jugo de manzana 'Golden Delicious' al 1%. Conidios de P. expansum germinaron a 1x10(7) mL-1 y conidios de B. cinerea germinaron a 5x10(5) mL-1. Los tratamientos con C. oleophila disminuyeron la germinación de conidios de 2-7x10(4) mL-1 para P. expansum y de 1-4x10(4) para B. cinerea. Los tratamientos con C. oleophila redujeron la germinación de conidios con promedios de 99% para P. expansum y de 96% para B. cinerea. Los azúcares consumidos por L07 rugosa fueron de 0.026 mg mL-1 contra B. cinerea y de 0.056 mg mL-1 contra P. expansum. El consumo de azúcares corrobora la reducción de germinación de conidios. P. expansum consumió 1.69 μg L-1 de proteínas, mientras que L07 rugosa consumió la mayor cantidad con 47.95 μg L-1. B. cinerea consumió 8.95 μg L-1 y L06 36.89 μg L-1, que fue estadísticamente igual al de L07 rugosa con 27.96 μg L-1. Las cepas de C. oleophila, ejercieron un biocontrol de B. cinerea y P. expansum, en parte, por competencia de nutrientes.

Six Trichoderma spp. native strains were identified to specie and studied to determine their growth rate and antagonism against plant pathogen fungi. The strains were cultivated on Potato Dextrose Agar to determine their morphological characteristics and growth rate. Molecular analysis was carried out to identify their species. The antagonistic activity was tested by the dual cultures confrontation method. Although morphological characteristics of strains were similar to T. harzianum and T. viride, the molecular analysis showed that strains TC74, TC74M, T341, T359 and T479, were T. asperellum and T397 was T. longibrachiatum. Trichoderma strains mean growth rate at 25 °C ranged from 12 to 17 mmd-1. Inhibition of the B. cinerea growth ranged from 60% to 75% and mycelium overgrown from 25% to 100%. Inhibition of R. solani growth ranged from 34% to 52% and overgrown from 15% to 100%. Antagonistic activity of T. asperellum TC74, T341 and T359 was similar to reference strains T22 and Th. The same three strains inhibited the M. phaseolina growth from 44% to 64%, R. solani from 51% to 59%, P. omnivora 28% to 37% and Fusarium sp. 5%to 14%.

Seis cepas nativas de Trichoderma spp. se identificaron a especie y se determinó su tasa de crecimiento y antagonismo contra diferentes hongos fitopatógenos. Sus características morfológicas y tasa de crecimiento se determinaron cultivándolas en Papa Dextrosa Agar y mediante un análisis molecular se identificó la especie. El antagonismo fue evaluado mediante confrontación por cultivos duales. Morfológicamente las cepas fueron similares a T. harzianum y a T. viride; sin embargo, el análisis molecular identificó a TC74, TC74M, T341, T359 y T479, como T.asperellum y a T397 como T. longibrachiatum. La tasa de crecimiento promedio de las cepas a 25 °C varió de 12 a 17 mmd-1. La inhibición del crecimiento de B. cinerea varió 60% a 75% y el sobrecrecimiento sobre su micelio 25% a 100%. La inhibición de R. solani varió 34% a 52% y el sobrecrecimiento 15% a 100%. La actividad antagónica de T. asperellum TC74, T341 y T359 fue similar a las cepas de referencia T22 y Th. Estas tres cepas también inhibieron 44% a 64% el crecimiento de M. phaseolina, 51% a 59% el de R. solani, 28% a 37% el de P. omnivora y 5% a 14% el de Fusarium sp.