Equilibrio higroscópico en semillas forestales de zonas áridas y su efecto en la calidad fisiológica

Equilibrio higroscópico en semillas forestales de zonas áridas y su efecto en la calidad fisiológica  Las semillas forestales son el material mayormente utilizado para la producción masiva de plantas, las especies de zonas áridas no producen semilla todos los años, es necesario disponer de germoplasma en cantidad y calidad que permitan la obtención de nuevos individuos. Conocer la humedad en equilibrio, permite establecer los tiempos de almacenamiento seguro, durante un tiempo determinado. El objetivo de este trabajo fue evaluar el efecto del contenido de humedad de Equilibrio sobre la calidad fisiológica en semillas de Agave lecheguilla Torr., Lippia graveolens Kunt., y Nolina cespitifera Trel., durante el almacenamiento. Las semillas fueron almacenadas por un periodo de 90 días bajo 12 ambientes y evaluadas a 0, 15, 30, 60 y 90 días, con cuatro repeticiones, las pruebas de germinación y humedad de la semilla fueron realizadas utilizando procedimientos internacionales de la Asociación Internacional de Análisis de Semillas (International Seed Testing Association),(ISTA, 2014).  Las variables evaluadas fueron humedad de la semilla (HS) y semillas germinadas (SG), El diseño experimental fue factorial con arreglo de tratamientos completamente al azar. El análisis estadístico, mostró diferencias significativas (P < 0.01) entre tratamientos (condiciones de almacenamiento) para las tres especies. Las semillas almacenadas a 60-75% de humedad relativa y 5-15°C no perdieron de manera significativa su capacidad germinativa,  la HS osciló entre 12-13%, los valores más altos de HS se obtuvieron a 80-85% de humedad relativa y en respuesta el porcentaje de SG disminuyó de manera considerable entre 5.0 y 18.5 %. En las tres especies en estudio la humedad en equilibrio ésta fuertemente influenciada por las condiciones de almacenamiento, alta humedad relativa y temperatura ocasionan humedad de equilibrio alta, afectando de manera negativa la calidad fisiológica y ocasionando un deterioro rápido

ADICIÓN DE ÁCIDO CÍTRICO EN LA SOLUCIÓN NUTRITIVA PARA TOMATE EN UN SUELO CALCÁREO

Los ácidos orgánicos, principalmente el ácido cítrico, pueden mejorar la disponibilidad de nutrimentos para las plantas, de igual manera mejoran la calidad de la planta y del fruto. El objetivo del presente trabajo fue determinar el efecto de la adición de ácido cítrico (AC), aplicado en la solución nutritiva, sobre el impacto en el crecimiento, producción y calidad de fruta de tomate en un suelo calcáreo. La adición del AC propició modificaciones positivas en el diámetro del tallo, el peso fresco y biomasa seca de la planta. Respecto al testigo la producción de fruto aumentó en 69% con el tratamiento 10-6 M de ácido cítrico. El potencial antioxidante, la conductividad eléctrica, la acidez titulable y la vitamina C en el fruto respondieron también favorablemente a la adición de ácido cítrico en la concentración de 10-6 y 10-4. M. Los resultados del estudio indicaron que es factible utilizar el AC como una herramienta de manejo agronómico para mejorar la nutrición de los cultivos

Comportamiento agronómico de líneas para la producción de semilla de sorgo

The objective of the study was to evaluate the agronomic performance of A, B isogenic lines and R grain sorghum lines which restore androfertility of sorghum for grain production. This work was performed during the spring-summer 2010 in Marin Nuevo Leon under drip irrigation. Days to flowering, seed yield per plant, brix degrees and weight of 1000 seeds were measured. The statistical analysis with the benchmark test of averages with independent samples was realized in A, B sorghum lines to days to flowering, seed yield per plant, brix degrees and weight of 1000 seeds. In R lines the analysis of variance and DMS (P<0.05%) test was performed. A an B lines were not completely isogenic; there are A and R lines that may be crossed to produce commercial sorghum grain seed. B and R lines might be used as varieties and A, R parental lines planting splits were defined to produce hybrid sorghum seed.El objetivo de esta investigación fue evaluar el comportamiento agronómico de líneas isogénicas A, B y líneas R restauradoras de la androfertilidad de sorgo para grano. El ensayo se realizó durante el ciclo primavera-verano 2009-2010 en Marín Nuevo León, México, bajo riego por goteo. Se evaluaron días a floración, rendimiento de semilla en gramos por planta, grados Brix en el jugo del tallo y peso de 1000 semillas. Se realizó el análisis estadístico con la prueba de comparación de medias con muestras independientes en las líneas isogénicas A y B. En las líneas R, se realizó el análisis de varianza y la prueba DMS (P<0,05%). Algunas de las líneas A y B no fueron isogénicas. Se encontraron líneas A y R que en cruza pueden formar híbridos para la producción comercial de grano de sorgo. Se identificaron líneas B y R que pueden utilizarse como variedades y se definieron los días de siembra para sincronizar la floración de las líneas progenitoras A y R para la producción de semilla híbrida de sorgo

Agronomic Evaluation and Physiological Quality in Triticale, under Two Production Systems in the Laguna Region

Objective: to evaluate ten triticale genotypes to evaluate the quality of the seeds, under two production systems with one cut and without cut in the municipalities of Matamoros (L1) and Francisco I. Madero (L2), Coahuila. Design/Methodology/Approach: the agronomic variables evaluated were:,Grain yield (RG), grains per ear (GPE), ear length (LE), spikelets per spike (EE) and plant height (AP). Variables at the laboratory level were: germination percentage (PG), anormal seedlings (PA), seeds without germinate (SSG), dry weight (PS), plumule length (LP) and radicle length (LR). Statistical analysis was performed with the PROC ANOVA procedure, of the SAS software. Results: for L1, a higher grain yield, compared with L2, however, for the variable number of grains per ear it was higher in L2. In the physiological quality of seeds for L2, the highest values they were in the variables germination percentage and radicle length. In the comparison of production systems, the best answer was for the system  without  cut in both locations, therefore, good triticale seed can be produced quality with acceptable grain yield. Study limitations/implications: It is required to describe the behavior of triticale in the spring-summer agricultural cycle in the central region of the country. Findings/Conclusions: The productive behavior of triticale genotypes was variable depending on the production system, likewise different effect on the physiological quality of the harvested seed.Objective: To evaluate ten triticale genotypes to assess the quality of the seeds under two production systems, with cut and without cut, in the municipalities of Matamoros (L1) and Francisco I. Madero (L2), Coahuila,Mexico.Design/Methodology/Approach: The agronomic variables evaluated were: Grain yield (GY), number of seeds per spike (NSS), spike length (SL), number of spikelets per spike (SS) and plant height (PH). Variables in the laboratory were: normal seedlings (NS), abnormal seedlings (AS), seeds without germinating (SWG), dry seedling weight (DW), plumule length (PL) and radicle length (RL). Statistical analysis was performed with the PROC ANOVA procedure, of the SAS software.Results: A higher grain yield was found for Matamoros (L1) compared to Francisco I. Madero (L2); however,for the variable number of seeds per spike it was higher in the latter (L2). For the physiological quality of seeds in L2, the highest values were in the variables normal seedlings and radicle length. In the comparison of production systems, the best response was for the system without cut in both locations; therefore, good quality triticale seed can be produced with acceptable grain yield.Study Limitations/Implications: It is necessary to describe the performance of triticale in the springsummer agricultural cycle in the central region of the country.Findings/Conclusions: The productive performance of triticale genotypes was variable depending on the production system, and there was also a different effect on the physiological quality of the harvested see

"Aspergillus" aflatoxigénicos: enfoque taxonómico actual

The genus Aspergillus has been studied for centuries due to its industrial and deterioration properties, and its effects on health. Its identification at a genus level is relatively simple, yet at a level of species it becomes more complicated, due to the similarities between both. Due to this, taxonomists currently recommend a polyphasic focus that includes, not only morphologic characteristics, but also biochemical and molecular characteristics. The aim of this investigation was to present the basic aspects concerning the polyphasic identification of these species.Aspergillus es un género estudiado desde hace siglos debido a sus propiedades industriales, de deterioro y efectos en la salud. Su identificación a nivel de género es relativamente sencilla, pero a nivel de especies se complica debido a las similitudes existentes entre las mismas. Debido a esto, actualmente, los taxónomos recomiendan un enfoque polifásico que comprende no sólo características morfológicas, sino también bioquímicas y moleculares. El presente trabajo se realizó con el objetivo de presentar los aspectos básicos concernientes a la identificación polifásica de estas especies

Uso de mallas sombra: una alternativa para la producción de tomate cherry / Shade nets: an alternative to increase the cherry tomato production

El uso de mallas sombra en la horticultura protegida es una técnica económica empleada para mejorar la radiación y evitar incrementos de temperatura. En la presente investigación se evaluó el efecto del uso de mallas sombra de cuatro colores (azul, negra, roja y perla) en la producción de tomate cherry. El rendimiento en la malla sombra de color perla se incrementó 116.66 % en comparación al rendimiento obtenido bajo la malla sombra de color negro y 122.85 % en comparación con el rendimiento obtenido en el testigo (sin malla). De acuerdo a los resultados de este estudio, la malla sombra perla se considera una alternativa viable para la producción de tomate cherry

Seed Physiological Potential of Capsicum annuum var. glabriusculum Genotypes and Their Answers to Pre-Germination Treatments

Piquin pepper (Capsicum annuum var. glabriusculum) is an important species that supports the economy of rural households; it is part of Mexican gastronomy and it is a highly valuable phytogenetic resource. There has been recent interest in domesticating and exploiting piquin pepper commercially, which has been limited until now due to the low germination rate, and this work had the purpose of promoting germination and determining the physiological capacity of genotypes. Ten piquin pepper genotypes from different geographical origins in Mexico were submitted to 11 pre-germination treatments. A completely randomized experimental design was carried out with arrangement in split-plot. The large plot had the treatments and the small plot had the genotypes. The results showed differences (p < 0.01) among treatments, genotypes, and treatment–genotype interaction. On one hand, treatments gibberellic acid (GA) and mechanical scarification + gibberellic acid (MSGA) increased the physiological potential of genotypes, reaching the highest values of germination speed (GS), germination index (IG) and germination percentage (GP); as well as the lowest values of dead seeds (DS) and hard Seeds (HS). In turn, the genotypes that presented the same condition were G8, G7, and G10. Regarding the interaction, each variable had a different condition. In conclusion, we can increase the physiological potential and solve the dormancy of piquin pepper seed by applying gibberellic acid. Likewise, the best genotypes were G8 and G10

Risk of COVID-19 after natural infection or vaccinationResearch in context

Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health

Risk of COVID-19 after natural infection or vaccinationResearch in context

Summary: Background: While vaccines have established utility against COVID-19, phase 3 efficacy studies have generally not comprehensively evaluated protection provided by previous infection or hybrid immunity (previous infection plus vaccination). Individual patient data from US government-supported harmonized vaccine trials provide an unprecedented sample population to address this issue. We characterized the protective efficacy of previous SARS-CoV-2 infection and hybrid immunity against COVID-19 early in the pandemic over three-to six-month follow-up and compared with vaccine-associated protection. Methods: In this post-hoc cross-protocol analysis of the Moderna, AstraZeneca, Janssen, and Novavax COVID-19 vaccine clinical trials, we allocated participants into four groups based on previous-infection status at enrolment and treatment: no previous infection/placebo; previous infection/placebo; no previous infection/vaccine; and previous infection/vaccine. The main outcome was RT-PCR-confirmed COVID-19 >7–15 days (per original protocols) after final study injection. We calculated crude and adjusted efficacy measures. Findings: Previous infection/placebo participants had a 92% decreased risk of future COVID-19 compared to no previous infection/placebo participants (overall hazard ratio [HR] ratio: 0.08; 95% CI: 0.05–0.13). Among single-dose Janssen participants, hybrid immunity conferred greater protection than vaccine alone (HR: 0.03; 95% CI: 0.01–0.10). Too few infections were observed to draw statistical inferences comparing hybrid immunity to vaccine alone for other trials. Vaccination, previous infection, and hybrid immunity all provided near-complete protection against severe disease. Interpretation: Previous infection, any hybrid immunity, and two-dose vaccination all provided substantial protection against symptomatic and severe COVID-19 through the early Delta period. Thus, as a surrogate for natural infection, vaccination remains the safest approach to protection. Funding: National Institutes of Health