ABSTRACT In Mexico, Creole corn has presented problems related to seed rot. Therefore, the objective of this study was to determine the frequency of fungi associated with Creole corn seeds. From January to February 2019, 13 Creole corn samples were collected from several localities in Guerrero, Mexico. The samples were processed in PDA culture medium and the frequency of each fungus was estimated based on cultural characteristics and taxonomic keys. Considering symptomatic corn seed samples, Fusarium oxysporum was recorded in eight samples at 97.2%, followed by F. graminearum, isolated from race “Olotillo 1” at 94.4% and from race “Cónico pepitilla” at 58.3%. Phomopsis sp. was isolated at 100% from race “Olotillo 2”. Gibberella moniliformis was isolated from “Elotes Occidental 1” at 83.3%, while the least frequent isolate (19.4%) from “Pepitilla” was Sarocladium strictum, which was recorded in three samples at the low values of 11.1% and 2.8% for races “Arrocillo 2” and “Pepitilla”, respectively; Talaromyces variabilis was found in two samples at 11.1% and 2.8% from “Arrocillo 2” and “Cónico pepitilla”, respectively; Stenocarpella macrospora was isolated at 72.2% from “Pepitilla”. Aspergillus flavus was obtained from “Cónico Pepitilla” at 16.7%, while Setosphaeria turcica and Emericella sp. were less frequently isolated. Considering asymptomatic seeds of race “Cónico pepitilla”, F. oxysporum was isolated at 8.3%, Fusarium acuminatum at 8.3% and Gibberella moniliformis at 41.7%; from asymptomatic seeds of “Olotillo 1” and “Olotillo 2”, Phomopsis sp. was isolated at 50% and Rhizoctonia solani at 50%, respectively. In the present study, the fungi F. oxysporum, Phomopsis sp., G. moniliformis and F. graminearum were most frequently associated with Creole corn seeds.

RESUMO No México, o milho crioulo apresenta problemas de podridão das sementes. Portanto, o objetivo desta pesquisa foi determinar a frequência de fungos associados a sementes de milho crioulo. De janeiro e fevereiro de 2019, 13 amostras de milho crioulo foram coletadas em localidades de Guerrero, México. As amostras foram processadas em meio de cultura BDA e a frequência de cada fungo foi estimada com base nas características culturais e chaves taxonômicas. Nas amostras sintomáticas de sementes de milho, Fusarium oxysporum foi registrado em oito amostras com 97,2%, seguido por F. graminearum isolado na raça de milho “Olotillo 1” com 94,4% e na raça “Cónico pepitilla” com 58,3%. Phomopsis sp., foi isolado 100% na raça “Olotillo 2”. Gibberella moniliformis, foran isolados de “Elotes Occidental 1” com 83,3% e o menos frequente (19,4%) em “Pepitilla” foi Sarocladium strictum registrado em três amostras com valores baixos de 11,1% e 2,8% na raça de milho “Arrocillo 2” e “Pepitilla”, Talaromyces variabilis em duas amostras com 11,1% e 2,8% em “Arrocillo 2” e “Cónico pepitilla”. Stenocarpella macrospora foi isolado em 72,2% da raça de milho “Pepitilla”. Aspergillus flavus em “Cónico Pepitilla” com 16,7%, Setosphaeria turcica e Emericella sp., foi isolado com menor frequência. Em sementes assintomáticas da raça “Cónico pepitilla” foi isolado F. oxysporum com 8,3%, Fusarium acuminatum 8,3%, Gibberella moniliformis em 41,7%, em sementes assintomáticas de “Olotillo 1” e “Olotillo 2” Phomopsis sp., foi isolado em 50% e Rhizoctonia solani com 50%. Neste estudo, os fungos F. oxysporum, Phomopsis sp., G. moniliformis e F. graminearum foram os mais frequentemente associados às sementes de milho crioulo.

RESUMO A doença manchada de vinagreira causada por Corynespora cassiicola afeta a produção de cálice no México. O objetivo deste estudo foi avaliar vinte e dois genótipos de vinagreira contra C. cassiicola em casa de vegetação. Com base nas área abaixo da curva de progresso da doença (AACPD) foi possível detectar genótipos suscetíveis, tolerantes e resistentes. Dada a incidência nas folhas, os genótipos suscetíveis foram Conpoz, Sudlaz, Morcot e Sudigua (valores de AACPD 7379,2 a 5891,7); tolerantes foram Conayu e Chinxal (AACPD 1341,6 e 1313,2). Enquanto isso, pela severidade nas folhas, os suscetíveis foram Sudigua, Conpoz e Morena2 (AACPD de 788,4 a 436,3); tolerantes foram Almatech, Crioxal, Rojatec e Conayu (37,7 a 28,76 de AACPD). Enquanto, avaliando a incidência em cálices, genótipos suscetíveis foram; Morena2, Morena, Conpoz, Descop e Chinayu (AACPD de 6572,1 a 2319,4); para a gravidade suscetível foram Morena2, Descop, Morena, Cabxal, Chinayu e Conpoz (AACPD de 3355,4 a 779,2). A incidência e severidade nos cálices detectaram genótipos resistentes, que foram Almatech, Criolaz2, Criocot, Criolaz, Rojatec, Criopoz, Crioxal, Chinxal e Conayu (0,0 de AACPD). Neste estudo, foram detectados genótipos tolerantes e resistentes à mancha foliar e cálice causada por C. cassiicola em vinagreira.

ABSTRACT Roselle spot caused by Corynespora cassiicola affects calyx production in Mexico. The aim of the present study was to evaluate twenty-two roselle genotypes against C. cassiicola under greenhouse conditions. The area under the disease progress curve (AUDPC) was used to detect susceptible, tolerant and resistant genotypes. Considering the incidence in leaves, susceptible genotypes were Conpoz, Sudlaz, Morcot and Sudigua (AUDPC values of 7379.2 to 5891.7); tolerant genotypes were Conayu and Chinxal (AUDPC 1341.6 and 1313.2). Based on the severity in leaves, susceptible genotypes were Sudigua, Conpoz and Morena2 (AUDPC from 788.4 to 436.3); tolerant genotypes were Almatech, Crioxal, Rojatec and Conayu (37.7 to 28.76 AUDPC). Assessment of the incidence in calyces indicated that susceptible genotypes were Morena2, Morena, Conpoz, Descop and Chinayu (AUDPC from 6572.1 to 2319.4); for the severity in calices, susceptible genotypes were Morena2, Descop, Morena, Cabxal, Chinayu and Conpoz (AUDPC from 3355.4 to 779.2). Incidence and severity on calyces evidenced resistant genotypes, which were Almatech, Criolaz2, Criocot, Criolaz, Rojatec, Criopoz, Crioxal, Chinxal and Conayu (0.0 AUDPC). In the present study, tolerant and resistant genotypes were detected to leaf and calyx spot caused by C. cassiicola in roselle.

Resumen La especie Solanum lycopersicum L. muestra variación en intensidad de color, forma y tamaño de fruto, hábitos de crecimiento, por lo que es importante identificar variedades sobresalientes en características agronómicas y someterlos a un proceso de mejoramiento genético. El objetivo del presente estudio fue evaluar el efecto de la inoculación con Klebsiella variicola, K. quasipneumoniae y K. pneumoniae en plantas de 19 ecotipos de tomate. Se estableció un experimento en un diseño de bloques completos al azar bajo un arreglo factorial generalizado con cinco repeticiones en condiciones de bioespacio. Las variables evaluadas fueron días a floración, peso fresco de fruto, longitud de raíz, peso fresco de raíz, volumen de raíz, peso seco de raíz y número de semillas. El análisis de varianza mostró diferencias significativas en las fuentes de variación cepas de bacteria y ecotipos de tomate. Los resultados indicaron variación en el sistema radicular, características agronómicas y componentes de rendimiento de fruto con la aplicación de bacterias promotoras de crecimiento vegetal en ecotipos nativos de tomate. Las cepas bacterianas favorecen la producción de frutos de tomate con atributos para ser comercializados.

Summary The species Solanum lycopersicum L. shows variation in intensity of color, fruit shape and size, growth habits, so it is important to identify outstanding varieties in agronomic characteristics and subject them to a genetic improvement process. The objective of this study was to evaluate the effect of inoculation with Klebsiella variicola, K. quasipneumoniae and K. pneumoniae in plants of 19 tomato ecotypes. An experiment was established in a randomized complete block design under a generalized factorial arrangement with five replications under biospace conditions. The variables evaluated were days to flowering, fresh fruit weight, root length, fresh root weight, root volume, dry root weight and number of seeds. The analysis of variance showed significant differences in the sources of variation bacterial strains and tomato ecotypes. Results indicated variation in the root system, agronomic characteristics and fruit yield components with the application of plant growth promoting bacteria in native tomato ecotypes. Bacterial strains favor the production of tomato fruits with attributes to be commercialized.

Agronomic traits and genetic components are indicators of quality; additional factors are important to study the traits of germplasm in a breeding program. The effects of general (GCA) and specific (SCA) combining adequacy and the type of gene action for agronomic traits of regular maize (Zea mays L.) seeds and high-quality protein were analysed. The genetic material consisted of 10 maize inbred lines: four of regular grain and six high-quality protein. The variables analysed were: days to male and female flowering, plant and ear height, plant and ear score, and grain yield. The results showed significant variation among genotypes (p≤ 0.01) on the effects of GCA and SCA for all agronomic variables. Lines were identified as: T-44, B-41, LT-155, T-45 and CML-144 C, with higher values of GCA, being 0.6379, 0.4592, 0.3286, 0.2945 and 0.3382 t ha-1, respectively, for grain yield. Furthermore, outstanding materials based on its identified SCA crosses 4 * 8 (B-41 * CML-144), 1 * 5 (T-45 * CLQ-6203), and 2 * 7 (T-44 * CML- 142), with SCA estimated values for grain yield of 1.0875, 0.9544 and 0.7591 t ha-1, respectively. The type of additive gene action was the predominant in agronomic characters.

Los caracteres agronómicos y sus componentes genéticos son indicadores de la calidad de semillas; además, son factores importantes para estudiar las características del germoplasma en un programa de mejoramiento. Se analizaron los efectos de aptitud combinatoria general (ACG) y específica (ACE) y el tipo de acción génica de caracteres agronómicos de la semilla de maíz (Zea mays L.) normal y de alta calidad de proteína. El material genético consistió de 10 líneas endogámicas de maíz: cuatro de grano normal y seis de alta calidad de proteína. Se analizaron las variables: días a floración masculina y femenina, altura de planta y mazorca, calificación de planta y mazorca, y rendimiento de grano. Los resultados mostraron variación significativa entre genotipos (p≤ 0.01) en los efectos de ACG y ACE para todas las variables agronómicas. Se identificaron líneas como: T-44, B-41, LT-155, T-45 y CML-144 C, con valores mayores de ACG, siendo 0.6379, 0.4592, 0.3286, 0.2945 y 0.3382 t ha-1, respectivamente, para rendimiento de grano. Además, se identificaron materiales sobresalientes con base a su ACE las cruzas 4 * 8 (B-41 * CML-144), 1 * 5 (T-45 * CLQ-6203), y 2 * 7 (T-44 * CML-142), con valores estimados de ACE para rendimiento de grano de 1.0875, 0.9544 y 0.7591 t ha-1, respectivamente. El tipo de acción génica aditiva fue la que predominó en los caracteres agronómicos.

In this paper, the results about xylophagous macrofungi collected in the tropical deciduous forest from municipality of Cocula, Guerrero State in 2009 and 2010 are presented. In this study, 27 explorations were performed, collecting 544 specimens and 75 species identified, of which 12 correspond to the ascomycetes and 63 to the basidiomycetes; and 58 species are reported for the first time to Guerrero State and three are new records for Mexico: Hypoxylon fuscopurpureum, Nemania diffusa and Dendrocorticium polygonioides.

En este trabajo se presentan los resultados sobre los macromicetos xilófagos recolectados en el bosque tropical caducifolio del municipio de Cocula del estado de Guerrero durante 2009 y 2010. En este estudio fueron realizadas 27 exploraciones, recolectándose 544 especímenes y se determinaron 75 especies, de las cuales 12 corresponden a los ascomicetes y 63 a los basidiomicetes; de éstos, 58 especies se reportan por primera vez para el estado de Guerrero y tres constituyen nuevos registros para México: Hypoxylon fuscopurpureum, Nemania diffusa y Dendrocorticium polygonioides.

In México ilama fruit (Annona diversifolia Saff.) is normally sold with cracks at the base of the peduncle and without it. Consequently, it has a short shelf life and is more susceptible to rot. This study evaluates the biochemical, biophysical and physiological changes during development of white and pink pulped ilama fruit to determine its growth and maturation pattern on the plant. Open flowers on 30 trees (15 white pulp and 15 pink pulp) located in San Lorenzo, Municipality of Ajuchitlán, Guerrero, México, were tagged. Samples were taken at different fruit growth stages to record total fruit weight, proportion of pulp and peel, respiratory intensity, ethylene production, total and reducing sugars, total soluble solids (°Bx), and vitamin C content. Both types of fruit (white and pink pulp) had a double sigmoid growth pattern with a period of total development of 99 d after flowering (DAF). The slow fruit growth phase coincided with a decrease in respiratory intensity; ethylene production was not detected until 99 DAF, when maximum accumulation of total and reducing sugars and °Bx were recorded. However, both types of fruits initiated a significant increase in total and reducing sugars and °Bx as of 85 DAF, indicating the beginning of the ripening process.

En México el fruto de ilama (Annona diversifolia Saff.) normalmente se comercializa agrietado en la base del pedúnculo y sin éste. En consecuencia tiene corta vida de anaquel y es más susceptible a las pudriciones. En este trabajo se evaluaron los cambios bioquímicos, biofísicos y fisiológicos durante el desarrollo del fruto de ilama con pulpa blanca y rosa, con el objetivo de conocer su patrón de crecimiento y maduración en la planta. Se etiquetaron flores abiertas de 30 árboles (15 de pulpa blanca y 15 de pulpa rosa) ubicados en el poblado de San Lorenzo, Municipio de Ajuchitlán, Guerrero, México. Se realizaron muestreos en diferentes etapas de crecimiento de los frutos, evaluándose en cada uno de ellos el peso total del fruto, proporción de pulpa y cáscara, intensidad respiratoria, producción de etileno, azúcares totales y reductores, sólidos solubles totales (°Bx) y contenido de vitamina C. Ambos tipos de fruto (pulpa blanca y rosa) presentaron un patrón de crecimiento doble sigmoide con un periodo total de desarrollo de 99 d después de la floración (DDF). La fase lenta de crecimiento del fruto coincidió con una disminución en la intensidad respiratoria, la producción de etileno se detectó sólo hasta 99 d después de la floración, que coincidió con la máxima acumulación de azúcares totales, reductores y °Bx. Sin embargo en el fruto de ambos tipos se inició un aumento significativo en el contenido de azúcares totales, reductores y °Bx a partir de los 85 DDF, lo que indica el inicio del proceso de maduración.