Study of the Performance of the Organic Extracts of Chenopodium ambrosioides

There are many ways to obtain metal nanoparticles: biological, physical, and chemical ways and combinations of these approaches. Synthesis assisted with plant extracts has been widely documented. However, one issue that is under discussion refers to the metabolites responsible for reduction and stabilization that confine nanoparticle growth and prevent coalescence between nanoparticles in order to avoid agglomeration/precipitation. In this study, Ag nanoparticles were synthesized using organic extracts of Chenopodium ambrosioides with different polarities (hexane, dichloromethane, and methanol). Each extract was phytochemically characterized to identify the nature of the metabolites responsible for nanoparticle formation. With methanol extract, the compounds responsible for reducing and stabilizing silver nanoparticle were associated with the presence of phenolic compounds (flavonoids and tannins), while, with dichloromethane and hexane extracts, the responsible compounds were mainly terpenoids. Large part of the reducing activity of secondary metabolites in C. ambrosioides is closely related to compounds with antioxidant capacity, such as phenolic compounds (flavone glycoside and isorhamnetin), which are the main constituents of the methanol extracts. Otherwise, terpenoids (trans-diol, α-terpineol, monoterpene hydroperoxides, and apiole) are the central metabolites present in dichloromethane and hexane extracts

Morphological identification and characterization of the formation of floral primordium in Vanilla planifolia (Orchidaceae)

ABSTRACT Objective: To study the formation of floral primordia and individual flower development in the inflorescence of vanilla (Vanilla planifolia Jacks Ex. Andrews). Design/methodology/approach: The study site was located at Rancho Xanathtlan, in Barriles, municipality of Gutiérrez Zamora, Veracruz. Inflorescence primordia and young inflorescences (racemes) at different stages of development were sampled from three different stem positions: basal (11-15 internodes), middle (6-10 internodes) and distal (1-5 internodes). Four samplings were made from February to May, and five replicates of each stem position were used per sampling date. Observations and characterization were carried out with a stereo microscope. Results: Seven developmental stages were described for the racemes of V. planifolia: (I) differentiated meristem of the floral inflorescence, (II) appearance of the third bract, (III) initiation of the formation of the racemes, (IV) elongation of the floral primordia, (V) development and growth of the individual floral primordia in the acropetal direction, (VI) anthesis of the inflorescence in the acropetal direction and (VII) complete flowering of the raceme. Five developmental stages of formation of individual flower primordia within the inflorescence were also identified, which occurred from the appearance of the third bract in the acropetal direction. Limitations on study/implications: Although this study denotes the first observations on the floral phenology of V. planifolia, there are still many questions about the biochemical processes and the interaction of environmental aspects in this floral development. Findings/conclusions: First aspects of floral formation within the inflorescence as well as floral phenology in Vanilla planifolia were shown. Keywords: Floral growth, floral phenology, inflorescences, orchids.Objective: To morphologically identify and characterize the formation of floral primordium and the individual flower development in Vanilla planifolia Jacks Ex. Andrews. Design/Methodology/Approach: Inflorescence primordia and young inflorescences in different development stages were sampled from the stem internodes of the following positions: basal (11-15), middle (6-10), and distal (1-5). Four samples were taken from each stem position from February to May, with five repetitions per sampling date. Observations and characterization were made with a stereo microscope. The study site was located at Rancho Xanathtlan, in Barriles, municipality of Gutiérrez Zamora, Veracruz. Results: The development of the V. planifolia raceme is described in seven phases: (I) differentiated meristem of the floral inflorescence; (II) appearance of the third bract; (III) initiation of the racemes formation; (IV) elongation of the floral primordium; (V) development and growth of the individual floral primordium in the acropetal direction, (VI) anthesis of the inflorescence in the acropetal direction; and (VII) complete flowering of the raceme. The development of the buds in the raceme is described in five stages from the appearance of the third bract in the acropetal direction. Study Limitations/Implications: The biochemical processes and the interaction of environmental aspects on the floral development of V. planifolia pose questions that remain unanswered. Findings/Conclusions: The first aspects of floral formation within the inflorescence of Vanilla planifolia were determined, along with its floral phenology

Biosynthesis of Silver Nanoparticles Using Chenopodium ambrosioides

Biosynthesis of silver nanoparticles (AgNPs) was achieved using extract of Chenopodium ambrosioides as a reducer and coating agent at room temperature (25°C). Two molar solutions of AgNO3 (1 mM and 10 mM) and five extract volumes (0.5, 1, 2, 3, and 5 mL) were used to assess quantity, shape, and size of the particles. The UV-Vis spectra gave surface plasmon resonance at 434–436 nm of the NPs synthesized with AgNO3 10 mM and all extract volumes tested, showing a direct relationship between extract volumes and quantity of particles formed. In contrast, the concentration of silver ions was related negatively to particle size. The smallest (4.9 ± 3.4 nm) particles were obtained with 1 mL of extract in AgNO3 10 mM and the larger amount of particles were obtained with 2 mL and 5 mL of extract. TEM study indicated that the particles were polycrystalline and randomly oriented with a silver structure face centered cubic (fcc) and fourier transform infrared spectroscopy (FTIR) indicated that disappearance of the –OH group band after bioreduction evidences its role in reducing silver ions

Intercambio de gases y relaciones hídricas durante el retraso de la senescencia foliar de trigo (Triticum aestivum L.) por la citocinina bap

Se estudió el efecto de la citocinina 6-bencilaminopurina (BAP) en el intercambio de gases y relaciones hídricas de Triticum aestivum L. durante el retraso de la senescencia foliar en invernadero. Plántulas de 21 días después de la siembra (DDS) fueron asperjadas con BAP 0,1mM o agua (testigo) cada 3 días por 20 días. El retraso de senescencia foliar en las plantas tratadas con BAP fue monitoreado mediante cuantificación de clorofila y proteína soluble total. El intercambio de gases se estimó mediante conductancia estomática (gs) y tasa de fijación de CO2. Las relaciones hídricas se evaluaron midiendo el potencial de agua total (ΨA) y sus componentes, osmótico (Ψs) y de turgencia (Ψt), cada 5 días por 20 días. Las hojas con BAP mostraron mayor concentración de clorofila y proteína total que el control tras 26 DDS, diferencias que aumentaron con el tiempo y a los 41 DDS fueron 7 veces mayores que el control. La gs registró valores no significativamente diferentes al estado verde pre-senescente. Estas respuestas se asociaron con tasas mayores de fijación de CO2, con concentraciones cercanas a las hojas verdes pre-senescentes (6,2μmol·CO2·m-2·s-1). El ΨA se mantuvo constante bajo BAP y Ψs fue significativamente menor que en los testigos, favoreciendo la retención de solutos en el citoplasma de hojas con retraso de senescencia. El Ψt de las hojas tratadas fue mayor que su respectivo testigo de 31 a 41 DDS. Por tanto, la citocinina BAP promovió el mantenimiento de la tasa de fijación de CO2 y las relaciones hídricas durante el retraso de la senescencia foliar

Resistencia a ruptura y calidad fisiológica en semillas de maíz bajo compresión axial

The physical, physiological and sanitary qualities of corn seeds are reduced due to the mechanical damage caused by the mechanization of the production process. Knowing the strength and displacement critical values according to the type of endosperm will help decrease the damage during the cleaning, drying, storing and handling processes. This study assessed the strength and displacement from compression, the visible damage and the physiological quality of corn seeds from the following varieties: Cacahuacintle (floury), HS-2 (semi-floury) and Popcorn (hard) considering a humidity of 12 and 20%. The percentage of soft endosperm in Cacahuacintle, HS-2 and Popcorn was 76.20, 33.43 and 15.27%, respectively, while the percentage of hard endosperm was 5.25, 48.93 and 65.21%, respectively. The displacement and the strength for the Cacahuacintle variety was 0.8264 mm and 274.71 N, for the HS-2 variety was 0.5499 mm and 309.07 N and for the Popcorn variety was 0.5066 mm and 356.29 N, while for 12 and 20% humidity it was 0.3279 mm and 312.52 N and 0.9520 mm and 313.81 N, respectively. The damage indexes in compressed seeds were 276.67, 327.78 and 220.01 for Cacahuacintle, HS-2 and Popcorn, respectively, while for uncompressed seeds (control group) the damage indexes were 0.00. Germination was 85.20% for uncompressed seeds and 55% for those seeds subjected to fracture. The damage index was affected by the variety and the compression, but not by the humidity. Germination was not affected by the damage index, but it was affected by humidity and compression.La calidad física, fisiológica y sanitaria de la semilla se reduce debido al daño mecánico ocasionado por la mecanización del proceso de beneficio. Conocer los valores críticos de la fuerza y el desplazamiento a la compresión en función del tipo de endospermo, permitirá ayudar a disminuir el daño durante dicho proceso de limpieza, secado, almacenaje y manejo. En el presente estudio se evaluaron: la fuerza y el desplazamiento a compresión de ruptura, el daño visible y la calidad fisiológica de semillas de maíz de las variedades: Cacahuacintle (harinoso), HS-2 (semi-harinoso) y Palomero (duro) con humedad de 12 y 20%. El porcentaje de endospermo suave en Cacahuacintle, HS-2 y Palomero fue de 76.20, 33.43 y 15.27%, mientras que el de endospermo duro fue 5.25, 48.93 y 65.21%. El desplazamiento y la fuerza para Cacahuacintle, HS-2 y Palomero fue de 0.8264 mm y 274.71 N, 0.5499 mm y 309.07 N, y 0.5066 mm y 356.29 N; mientras que para 12 y 20% de humedad fue de 0.3279 mm y 312.52 N y 0.9520 mm y 313.81 N. Los índices de daño en semillas comprimidas fueron 276.67, 327.78 y 220.01 para Cacahuacintle, HS-2 y Palomero; mientras que para semillas sin comprimir (testigos) fue de 0.00. La germinación fue de 85.20 y 55% para semillas sin comprimir y para las sometidas a ruptura. El índice de daño estuvo afectado por la variedad y la compresión, pero no por la humedad. La germinación no estuvo afectada por el índice de daño, peri sí por la variedad, la humedad y la compresión