Organic extracts for fall armyworm (Spodoptera frugiperda) control in native corn (Zea mayz L.)

Objective: Determine the incidence of fall armyworm in corn plots and evaluate the insecticidal effect of garlic extract and rue essential oil and understand their phytochemistry. Design/methodology/approach: The fall armyworm incidence was determined through the “five of golds” systematic sampling, composed of 20 plants per sampling point (100 plants in each plot). This assessment was conducted in 15 plots of native corn in the municipality of Cherán, Michoacán. Control bioassays were also tested, in the laboratory and field; where rue essential oil, garlic extract, cypermethrin, and an absolute control (water) were evaluated. Results: The highest fall armyworm incidence (18%) occurred in a corn plot at Andasticua. In the laboratory, cypermethrin induced the highest fall armyworm mortality (100%), followed by rue essential oil (83%). In the field, both the insecticide and the rue essential oil reduced lepidopteran incidence. The main component of the essential R. graveolens oil is the semivolatyl cinnamoyl chromen (IUPAC name: 2-(3-phenylprop-2-enoyl)chromen-4-one). Limitations of the study/implications: The present research has no major limitations. Findings/conclusions: Both products, cypermethrin, and rue essential oil, effectively control fall armyworms in the laboratory and the field environments

Efecto de Methylobacterium extorquens en el desarrollo del tomate en presencia o ausencia de Fusarium oxysporum

The wilting of tomato (Fusarium oxysporum) promotes the excessive use of synthetic fungicides, which are not economically or environmentally viable. This work proposes the use of Methylobacterium extorquens to determine its effect on plant development and the signaling pathway, for the defense of tomato plants, against phytopathogens. From tomato seeds var. SUN 7705 embedded and plants sprinkled with the bacteria at a concentration of 109 CFU mL-1, were challenged to the plant with the fungus in two tests. Variables of root length in seedlings, plant height, leaf amplitude, yield, total dry weight of the plant and dry root weight were measured. A completely randomized design with six treatments and four repetitions was used, two plants formed the experimental unit. Likewise, an essay was carried out on the expression of defense genes, in tomato seedlings of the same variety. Significant statistical differences (p≤ 0.05) were found between treatments embedded and sprinkled with M. extorquens and the treatments inoculated with F. oxysporum and the controls, reflecting in the seedling root length, plant height, leaf amplitude, dry weight of the plant and the root, as well as in the yield. However, the genes encoding the phenylalanine ammonium lyase (PAL), protein (PR-6), superoxide dismutase (SOD) and lipoxygenase (LOX) enzyme group, were not significantly expressed in seedlings treated with M. extorquens.La marchitez del tomate (Fusarium oxysporum) promueve el uso desmedido de fungicidas sintéticos, que no son económica ni ambientalmente viables. Este trabajo plantea el uso de Methylobacterium extorquens para determinar su efecto sobre el desarrollo vegetal y la vía de señalización, para la defensa de plantas de jitomate, contra fitopatógenos. A partir, de semillas de tomate var. SUN 7705 embebidas y plantas asperjadas con la bacteria a una concentración de 109 UFC mL-1, se retó a la planta con el hongo en dos ensayos. Se midieron variables de longitud de raíz en plántulas, altura de la planta, amplitud foliar, rendimiento, peso seco total de la planta y peso seco de la raíz. Se utilizó un diseño completamente al azar con seis tratamientos y cuatro repeticiones, dos plantas formaron la unidad experimental. Asimismo, se realizó un ensayo sobre la expresión de genes de defensa, en plántulas de tomate de la misma variedad. Se encontraron diferencias estadísticas significativas (p≤ 0.05) entre tratamientos embebidos y asperjados con M. extorquens y los tratamientos inoculados con F. oxysporum y los controles, reflejándose en la longitud de raíz de plántulas, altura de la planta, amplitud foliar, peso seco de la planta y de la raíz, así como en el rendimiento. Sin embargo, los genes que codifican para el grupo enzimático fenilalanina amonio liasa (PAL), proteínas (PR-6), superóxido dismutasa (SOD) y lipoxigenasa (LOX), no se expresaron significativamente en las plántulas tratadas con M. extorquens

Heterosis en el proceso germinativo y en caracteres de semilla del hí-brido de maíz (Zea mays L.) HAZUL 10E

Objective: To quantify the heterosis in physical and physiological characteristics of seeds of the simple and trilineal crosses of the maize hybrid HAZUL 10E. Methodology: Seeds of the genotypes that make up the HAZUL 10E maize hybrid (inbred lines and simple and trilineal crosses) were used. The experimental design was completely randomized with three repetitions. Physical characteristics of the seeds (weight, width, thickness, length, volume, density and the ratios width/length of seed and thickness/length of seed) and physiological (normal and abnormal seedlings, inert seeds, and lengths and dry matter of plumule, radicle and total) were evaluated. Heterosis and heterobeltiosis were determined and their differences between both crosses were tested with Student's t test. Results: Heterosis and heterobeltiosis were higher in the single cross than in the trilineal one. In the single cross, the higher values of both heterosis corresponded to plumule, radicle and total dry matter; followed by weight and seed volume. In the trilinear, the highest values corresponded to normal seedlings and radicle length and biomass, and total. The determining variables of the shape, the formation of normal seedlings and the elongation of the radicle, responded better to hybridization in the trilineal cross. Study limitations: None presented. Conclusions: In the single cross, heterosis increased the seed size and the biomass accumulated in the seedlings; while in the trilineal cross, it affected the shape of the seed and the seedlings produced

Antagonismo in vitro de aislados bacterianos de fresa comercial y silvestre vs. Botrytis cinerea y Rhizopus stolonifer

La fresa es una fruta no climatérica, con una vida postcosecha muy corta. La pérdida de calidad del fruto puede deberse, entre otros factores a daños ocasionados por fitopatógenos. Entre los más comunes se encuentran los hongos causantes del moho gris (Botrytis cinerea), y podredumbre blanca (Rhizopus stolonifer) dos fitopatógenos de gran impacto por su velocidad de crecimiento la cual les permite colonizar la superficie de los mismos ocasionado importantes pérdidas económicas. Una alternativa para el control de los daños por patógenos en frutos postcosecha es el uso de antagonistas microbianos que pueden estar presentes en la planta o el fruto pero en densidades bajas. En este estudio se aislaron bacterias de tejido foliar y frutos de fresa silvestre (Duchesnea indica Andr. Fock) y comercial. Se seleccionaron aquellos aislados que presentaron los mayores porcentajes de inhibición del crecimiento micelial de ambos fitopatógenos in vitro. Se aislaron un total de 32 cepas de las cuales 15 provinieron de fresa silvestre y 24 de fresa comercial. Se obtuvieron solo nueve cepas con potencial biocontrolador para uno o ambos patógenos. Los mayores porcentajes de inhibición del crecimiento micelial oscilaron entre 67.1% y 81.7% para Botrytis cinerea y 45.5% a 73.2% para Rhizopus stolonifer. Estos fueron obtenidos por cuatro aislados dos obtenidos de fresa silvestre y dos de comercial, todos ellos con capacidad para controlar a ambos fitopatógenos