Background. In Mexico, corn is the most important crop, being an important input with food, economic, political, and social implications. However, intensive cultivation methods, based on chemical ...pesticides, monoculture and synthetic agrochemicals have caused a reduction in soil fertility and crop yields. An alternative, which can help restore soil fertility, increasing organic matter, moisture retention and the load of microorganisms, is mixed fertilizer. Stimulating, in addition, the defense systems of the plants and thus increasing the yield of the crops. Objective. To evaluate some fertilization schemes in Chalqueño maize plants through the measurement of some growth and yield variables. Methodology. A completely randomized block experimental design was established with three repetitions, where four fertilization schemes were evaluated (T1, control without fertilizer input; T2, chemical fertilizer; T3, organic fertilizer; and T4, chemical fertilizer + organic fertilizer) during the crop years 2019-2020. Results. The analyzes showed significant differences (p ≤ 0.05) between the evaluated treatments and years of cultivation. Being the T4 treatment, the one that obtained the best grain yield for the years 2019 and 2020, with values of 5.11 ± 0.05b t ha-1 and 6.57 ± 0.95a t ha-1, while the T1 treatment, recorded 1.59 ± 0.12f t ha-1 and 2.15 ± 0.38e t ha-1, respectively. Implications. With the information generated, it will be possible to implement the best fertilization scheme that provides the corn plants with all the necessary nutrients so that year after year they obtain the best grain yields. Conclusion. Through the results it was possible to demonstrate the negative effect of environmental factors (higher temperature and less rainfall), on the yield of the corn crop during the year 2019, with respect to the best yield result obtained for all the treatments during the year 2020 where a lower temperature and higher rainfall were recorded. Being equally evident the positive effect on the yield when plants were fertilized with the T4 treatment that provided to the corn crop with an adequate dose of moisture and macro and micronutrients.
Scyphophorus acupunctatus Gyllenhal (Coleoptera: Dryophthoridae), which also is known as agave weevil, is distributed across 5 continents. In Mexico, their presence has been reported in 12 states. ...Many species of Agave (Asparagaceae) are suitable hosts, though not all are equally suitable. Plant infestation can start with either female or male weevils, and their presence can be detected by gummy secretions emanating from feeding sites. The punctures are observed principally in the lower part of the trunk and external roots of the infested plants. Eggs are deposited singly or in clusters of up to 4 eggs at the feeding punctures after tissue decay has begun. The eggs hatch after about 5 d, and young larvae begin to create tunnels in the plant tissue. The larvae display 11 instars, and require about 50 to 90 d for development. The pupae normally require 11 to 14 d. The life cycle lasts between 105 to 137 d depending on the agave species with which the weevil is associated. The active insect can attack during any mo of the yr, although it is more frequent in the rainy season. Scyphophorus acupunctatus dispersion is determined by the attraction of volatile agave compounds. This insect apparently introduces different microorganisms that have been associated with the agave maladies. Plant extracts and seed powders have been assessed as potential botanical insecticides on larvae and pupae, with plant extracts causing mortality of 43 to 53% in larvae and 3 to 15% in pupae, and with seed powders causing 90 to 100% larval mortality. Synthetic insecticides have not been successful because the larvae and adults live inside the plant tissues. Alternative effective control tactics are needed to avoid increased damage and destruction of this important crop.
Six fungal strains were isolated from the textile industry effluent in which they naturally occur. Subsequently, the fungal strains were identified and characterized in order to establish their ...potential decolorizing effect on textile industry effluents. The strains of interest were selected based on their capacity to decolorize azo, indigo, and anthraquinone dyes. Three of the strains were identified as
(MAP03, MAP04, and MAP05) and the other three as
(MAP01, MAP02, and MAP06), while the efficiency of their decolorization of the dyes was determined on agar plate and in liquid fermentation. All the strains co-metabolized the dyes of interest, generating different levels of dye decolorization. Plate screening for lignin-degrading enzymes showed that the MAP03, MAP04, and MAP05 strains were positive for laccase and the MAP01, MAP02, and MAP06 strains for tyrosinase, while all strains were positive for peroxidase. Based on its decolorization capacity, the
(MAP03) strain was selected for the further characterization of its growth kinetics and ligninolytic enzyme production in submerged fermentation under both enzyme induction conditions, involving the addition of Acetyl yellow G (AYG) dye or wheat straw extract, and no-induction condition. The induction conditions promoted a clear inductive effect in all of the ligninolytic enzymes analyzed. The highest level of induced enzyme production was observed with the AYG dye fermentation, corresponding to versatile peroxidase (VP), manganese peroxidase (MnP), and lignin peroxidase (LiP). The present study can be considered the first analysis of the ligninolytic enzyme system of
in submerged fermentation under different conditions. Depending on the results of further research, the fungal strains analyzed in the present research may be candidates for further biotechnological research on the decontamination of industrial effluents.
In this study we evaluated the antagonism in vitro of Trichoderma harzianum strain VSL291 against 18 pathogens of cocoa fruits in dual culture. T. harzianum VSL291 inhibited the growth of the ...phytopathogenic fungi tested between 10.54 and 85.43%. The mycoparasitism of Moniliophthora roreri by T. harzianum VSL291 was studied by light and scanning electron microscopy. T. harzianum VSL291 hyphae grew in parallel with the hyphae of M. roreri and in some places these were united with the hyphae of the cocoa pathogen through small structures like apresorious that tangled in the pathogenic fungus preventing its growth. T. harzianum VSL291 produced lytic enzymes: beta -1,3-glucanases, chitinases, proteases, xylanases and lipases, when grown in minimal medium, with fungal cell walls as the sole carbon source. The highest proteolytic activities detected in T. harzianum VSL291 broth with M. roreri, Penicillium expansum and Byssochlamys spectabilis cell walls appear to be associated with increased activities of b-1,3 glucanases, chitinases, lipases, proteases and xylanases and biocontrol index derived from the experiments of confrontation. These results suggest that proteolytic enzymes according to their degree of induction could participate in the antagonistic effect of T. harzianum VSL291 against the fungi tested.
ABSTRACT Barley (Hordeum vulgare) is generally used for animal feed, and food and beer production industries. Its production is affected by phytopathogens, of which Ramularia collo-cygni, Puccinia ...spp., Pyrenophora teres and Cochliobolus sativus are of global concern. In Mexico, there are few studies available on the morphological and molecular identification of fungi responsible for causing fungal diseases of barley. Therefore, the objective of this work was to identify, morphologically and molecularly, fungi isolated from barley seeds. The strains were identified by morphological analysis and by sequencing of the conserved ITS1/5.8s/ITS2 region of the ribosomal gene. Morphologically, the strains were identified as P. teres and C. sativus, which was confirmed with bioinformatics techniques using BLAST and MEGA6 programs. The results showed that the strains isolated from barley seeds in the highlands of Mexico were consistent with the sequences of P. teres and C. sativus deposited in the GenBank. These results will allow identifying some of the species of native fungi found in barley seeds.
Background. Wild teosintle populations represent an important source for the increase of the genetic variability of the native corn of Mexico and Central America. Teosintle plants have a great ...tolerance to climatic variation and grow in a wide range of altitude; despite this, it is a plant genetic resource that is scarcely valued and therefore little studied. Objective. Morphologically characterize and make a phenological evaluation of accessions of Mexican wild teosintle from CIMMYT. Methodology. An experimental design of complete random blocks with three repetitions and plots of 4 rows of 2 m long with a separation between rows of 80 cm and a planting density adjusted to a hectare of 15,000 plants was used. Results. The Chalco and Mesa Central races of Zea mays ssp. mexicana were those that demonstrated the best values for the agronomic performance variables studied amongst of all the teosintle treatments evaluated. Implications. With the knowledge generated, it will be possible to establish management strategies for wild teosintle populations for commercial purposes. Conclusion. Based on the results obtained, the Chalco and Mesa Central races could be considered to increase genetic variability in genetic improvement programs of commercial corn, as food for farm animals and/or humans and in plant germplasm conservation programs.
The objective of this work was to evaluate the effectiveness of the putative biocontrol agents (PBA)
Bacillus paralicheniformis
and
Trichoderma asperelloides
in vitro and in vivo to control two of ...the most important tomato plant diseases: vascular wilt (
Fusarium oxysporum
) and early blight (
Alternaria alternata
). The assessment of the in vitro interactions between the PBA and the phytopathogenic fungi was performed by dual confrontation assays. The biocontrol effectiveness of the individual and combined PBA treatments towards individual phytopathogen inoculations was evaluated in tomato plants.
T. asperelloides
was able to exert an outstanding mycoparasitic effect on both phytopathogenic fungi in the in vitro tests by hyphal strangulation and penetration. In addition, the individual PBA treatments were effective in the biocontrol of
A. alternata
and
F. oxysporum
in tomato plants reducing the plant disease severity in more than 53.8 and 66.7% for each of the pathogens, respectively. On the other hand, the combined use of the tested strains showed similar effectiveness in the biocontrol of
A. alternata
, but no synergism was observed. In addition, it was concluded that
B. paralicheniformis
protected the plants from the attack of
A. alternata
through the induction of the systemic resistance of the plant. This study demonstrated the effectiveness of the individual and combined use of the strains tested for the biocontrol of
A. alternata
and
F. oxysporum
in tomato plants.
Background. Wild teosintle populations represent an important source for the increase of the genetic variability of the native corn of Mexico and Central America. Teosintle plants have a great ...tolerance to climatic variation and grow in a wide range of altitude; despite this, it is a plant genetic resource that is scarcely valued and therefore little studied. Objective. Morphologically characterize and make a phenological evaluation of accessions of Mexican wild teosintle from CIMMYT. Methodology. An experimental design of complete random blocks with three repetitions and plots of 4 rows of 2 m long with a separation between rows of 80 cm and a planting density adjusted to a hectare of 15,000 plants was used. Results. The Chalco and Mesa Central races of Zea mays ssp. mexicana were those that demonstrated the best values for the agronomic performance variables studied amongst of all the teosintle treatments evaluated. Implications. With the knowledge generated, it will be possible to establish management strategies for wild teosintle populations for commercial purposes. Conclusion. Based on the results obtained, the Chalco and Mesa Central races could be considered to increase genetic variability in genetic improvement programs of commercial corn, as food for farm animals and/or humans and in plant germplasm conservation programs.
Las plantas del género Agave representan un recurso forestal no maderable valioso para la recuperación del suelo. La epidermis de sus pencas contiene múltiples estomas y está cubierta por una capa ...cuticular. En la actualidad presentan una enfermedad fúngica que se caracteriza por la existencia de manchas grises circulares sobre las pencas, que con el tiempo se tornan necróticas; y en ocasiones, dichas lesiones terminan por secar las pencas. El objetivo de este trabajo fue describir la relevancia de la capa cuticular durante la colonización del hongo causante de la negrilla en Agave salmiana ssp. salmiana. La capa cuticular tiene un grosor de 121 ± 2.8 mm. Se observó una distribución homogénea de los estomas y se determinó la densidad (22.67-27.67 estomas mm-2) y el índice estomático (10.61-14.15). Los estomas observados son de tipo tetracítico, el tamaño de los ostiolos de 57.9 mm ± 5 de largo y 23.75 mm ± 1.25 de ancho y células epidérmicas poligonales isodiamétricas. Los cortes transversales y paradermales muestran que las hifas y los apresorios fúngicos quedan restringidos al lado anverso de la capa cuticular, por lo cual se corrobora la importancia de conservar la epidermis en las pencas del maguey pulquero.
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