Trichoderma posible micoparásito de Sporisorium reilianum y su influencia en el rendimiento del maíz

Objetivo - evaluar el efecto de cepas de Trichoderma en el control de Sporisorium reilianum y aumentar el rendimiento en un cultivo de maíz en el Valle del Mezquital, Hidalgo. Método - se desarrollaron experimentos in vitro e in vivo, las variables evaluadas fueron colonización por Trichoderma en cultivos duales, Incidencia, colonización de tejidos vegetales, altura y rendimiento. Los resultados serán relevantes para las regiones templadas donde se establezca maíz. Resultados - se demostró in vitro que el patógeno fue controlado principalmente por las cepas C5THBr y C3VM14. En incidencia en el cultivo, el tratamiento con el cual se obtuvo el mejor resultado fue con la cepa C4TVBr-no nativa (8.31%). Los tejidos fueron colonizados por Trichoderma desde un 19.99% (hojas) hasta un 53.3% (raíces). A excepción de C3VM14 todos los tratamientos tuvieron efecto positivo en altura de plantas. Con la cepa C5THBr-no nativa hubo un aumento de rendimiento de un 38.8%. Limitaciones - se requieren estudios detallados sobre los mecanismos de acción de las cepas en estudio. Principales hallazgos - las cepas de Trichoderma tanto nativas como no nativas pueden tener un efecto en el control de Sporisorium reilianum así como en el aumento del rendimiento del cultivo del maíz

Extractos vegetales y Trichoderma spp. en el control de Colletotrichum gloeosporioides (Penz.) Penz. y Sacc. en frutos de papaya maradol (Carica papaya L.) en postcosecha.

La actividad antifúngica de seis extractos vegetales fue evaluada in vitro e in vivo para controlar la antracnosis postcosecha en papaya. Extractos de ajo (Allium sativum) (concentraciones de 10 y 15 %) y canela (Cinnamomum zeylanicum) (0,0050; 0,0100; 0,0150 %) suprimieron el crecimiento micelial (100 %), inhibieron la germinación (100 %) y la esporulación del hongo (100 %). El extracto de canela a dosis de 0,0054 % aplicada antes y al momento de la inoculación con C. gloeosporioides fue la dosis óptima para el control de la severidad (canela 97.22% de efectividad respecto al testigo absoluto) de la antracnosis en frutos de papaya artificialmente inoculados, a mayores dosis la severidad aumentó. La fitotoxicidad (Cambio de color en los frutos) fue mayor al aumentar las dosis (0,012 y 0.030%) de extracto de canela, encontrándose diferencia estadística significativa con los testigos absoluto y químico, las dosis de ajo no mostraron diferencias estadísticas significativas respecto al testigo absoluto. El extracto de canela mostró un efecto inhibitorio de Colletotrichum gloeosporioides cuando es aplicado en forma preventiva. _______________ ABSTRACT: Antifungal activity of six plant extracts was evaluated in vitro and in vivo for the control of postharvest anthracnose of papaya. Garlic (10 and 15% concentrated) and Cinnamon (0,0050, 0,0100, 0,0150 %) extracts suppressed C. gloeosporioides mycelial growth (100%), inhibited the spore germination (100%) and sporulation (100%). Cinnamon (Cinnamomum zeylanicum) extracts (0,0054%) applied before and at the same time of the inoculation of C. gloeosporioides, represent optimal doses to control anthracnose severity (cinnamom 97.22% efectiveness compared to absolute control) of the papaya fruit antracnose artificially inoculated. However, phytotoxicity (color change of fruits) was greater increasing doses of cinnamon extract (0.0120 y 0.030%), showing statistically significant difference with absolute and chemical control. Garlic doses showed no statistically significant difference compared with absolute control. The cinnamon extract showed an inhibitory effect of Colletotrichum gloeosporioides when applied preventively.Tesis (Doctorado en Ciencias, especialista en Fitopatología).- Colegio de Postgraduados, 2013.Consejo Nacional de Ciencia y Tecnología (CONACYT)

Antagonismo de Trichoderma spp. vs hongos asociados a la marchitez de chile

In Mexico, more than 100 varieties of chili (Capsicum annuumL.) are planted, it is a highly profitable crop and represents an economic activity of national importance. Currently, it faces serious phytosanitary problems due to the presence of diseases such as the wilting of chili, caused by a complex of soil pathogens. To control these diseases, toxic and residual fungicides are used, which pollute the environment and induce genetic resistance in phytopathogens. Therefore, it is necessary to look for control alternatives to solve this problem, therefore, the objective of this work was to evaluate the antagonistic effect of Trichodermaspp., against the causal agents of wilting in in vitroconfrontations by means of dual cultures. The study was carried out in 2016, at the Intercultural University of the State of Puebla, Huehuetla, Puebla, Mexico. Three Trichodermaisolates from avocado tree rhizospheres, T. viride, T. harzianumand T. asperellumand three isolates of the phytopathogens P. capsici, F. oxysporumand R. solaniobtained from the roots of plant plants were evaluated chili with wilting symptoms. The isolates were morphologically characterized for identification. The three antagonistic fungi presented a high percentage of inhibition, T. asperellumshowed 88.25%, T. viride87.22% and T. harzianumwith 87.8%. Under the conditions of the study, T. asperellum, T. virideand T. harzianum, were efficient antagonistic microorganisms against the studied phytopathogens. It is suggested to carry out biocontrol evaluations with these isolates in the greenhouse and in the open field.En México se siembran más de 100 variedades de chile (Capsicum annuum L.), es un cultivo altamente redituable y representa una actividad económica de importancia nacional. Actualmente, enfrenta graves problemas fitosanitarios por la presencia de enfermedades como la marchitez del chile, causada por un complejo de patógenos de suelo. Para el control de estas enfermedades, se utilizan fungicidas tóxicos y residuales, que contaminan el ambiente e inducen resistencia genética en los fitopatógenos. Por ello, es necesario buscar alternativas de control para solucionar este problema, por tanto, el objetivo de este trabajo fue evaluar el efecto antagónico de Trichoderma spp., contra los agentes causales de marchitez en confrontaciones in vitro mediante cultivos duales. El estudio se llevó acabo en 2016, en la Universidad Intercultural de Estado de Puebla, Huehuetla, Puebla, México. Se evaluaron tres aislamientos de Trichoderma provenientes de la rizósferas de árboles de aguacate, T. viride, T. harzianum y T. asperellum y tres aislamientos de los fitopatógenos P. capsici, F. oxysporum y R. solani obtenidos de las raíces de plantas de chile con síntomas de la marchitez. Los aislamientos se caracterizaron morfológicamente para su identificación. Los tres hongos antagonistas presentaron alto porcentaje de inhibición, T. asperellum mostró el 88.25%, T. viride 87.22% y T. harzianum con 87.8%. En las condiciones del estudio, T. asperellum, T. viride y T. harzianum, resultaron microorganismos antagónicos eficientes contra los fitopatógenos. Se sugiere realizar evaluaciones de biocontrol con estos aislamientos en invernadero y a campo abierto

Effects of hydropriming on maize seeds (Zea mays L) and the growth, development, and yield of crops

Seed germination is a process that involves several phases, beginning with the uptake of water by dry seeds and ending with emergence. Based on current knowledge, several methodologies have been developed to manipulate this process in order to produce beneficial effects on crops. The hydropriming of maize seeds is one technique that has been used to lower the in-field germination time. The objective of the present study was to measure the effect of different hydropriming times on maize seeds and the subsequent growth, development, and yield of plants. The results demonstrated that seeds hydropriming for 12 and 18 hours germinated more rapidly in comparison with the control and 36-hour treatment. Yield was also affected as a function of the imbibition time. The generated data allowed for an optimal soaking time of 22.12 hours to be determined, resulting in an estimated yield of 16.6 t per hectare.Seed germination is a process that involves several phases, beginning with the uptake of water by dry seeds and ending with emergence. Based on current knowledge, several methodologies have been developed to manipulate this process in order to produce beneficial effects on crops. The hydropriming of maize seeds is one technique that has been used to lower the in-field germination time. The objective of the present study was to measure the effect of different hydropriming times on maize seeds and the subsequent growth, development, and yield of plants. The results demonstrated that seeds hydropriming for 12 and 18 hours germinated more rapidly in comparison with the control and 36-hour treatment. Yield was also affected as a function of the imbibition time. The generated data allowed for an optimal soaking time of 22.12 hours to be determined, resulting in an estimated yield of 16.6 t per hectare

Efficiency of Schinus molle Essential Oil against Bactericera cockerelli (Hemiptera: Triozidae) and Sitophilus zeamais (Coleoptera: Dryophthoridae)

The present study determines the chemical composition of Schinus molle essential oil and its mortality and repellent effect on Bactericera cockerelli immature stage and Sitophilus zeamais adults. Twenty-four compounds were identified and the most abundant were o-Cymene (29.04), 1R-α-Pinene (15.52), camphene (14.00), and β-myrcene (11.54). On the fifth-instar psyllid nymph, the LC50 and LC90 at 48 h were 442.67 and 864.29 ppm, and for the fourth-instar were 273.41 and 534.67 ppm. The maize-weevil registered an LC50 and LC90 of 343.25 and 986.96 ppm for the fifteenth day. A selection index (Si) of 0.37 with 800 ppm was registered, showing the highest repellent activity, while with the lowest concentration (50 ppm), non-repellent activity was recorded. However, all concentrations above 100 ppm showed repellency against the maize weevil. The study reveals, for the first time, the essential oil’s insecticidal effects on the fourth and fifth nymphal stage of the potato/tomato psyllid B. cockerelli and the usefulness of the essential oil as a repellent against adult of S. zeamais. The Si effect on maize weevil was grouped into categories

Efficiency of <i>Schinus molle</i> Essential Oil against <i>Bactericera cockerelli</i> (Hemiptera: Triozidae) and <i>Sitophilus zeamais</i> (Coleoptera: Dryophthoridae)

The present study determines the chemical composition of Schinus molle essential oil and its mortality and repellent effect on Bactericera cockerelli immature stage and Sitophilus zeamais adults. Twenty-four compounds were identified and the most abundant were o-Cymene (29.04), 1R-α-Pinene (15.52), camphene (14.00), and β-myrcene (11.54). On the fifth-instar psyllid nymph, the LC50 and LC90 at 48 h were 442.67 and 864.29 ppm, and for the fourth-instar were 273.41 and 534.67 ppm. The maize-weevil registered an LC50 and LC90 of 343.25 and 986.96 ppm for the fifteenth day. A selection index (Si) of 0.37 with 800 ppm was registered, showing the highest repellent activity, while with the lowest concentration (50 ppm), non-repellent activity was recorded. However, all concentrations above 100 ppm showed repellency against the maize weevil. The study reveals, for the first time, the essential oil’s insecticidal effects on the fourth and fifth nymphal stage of the potato/tomato psyllid B. cockerelli and the usefulness of the essential oil as a repellent against adult of S. zeamais. The Si effect on maize weevil was grouped into categories