ANÁLISIS DE CRECIMIENTO ESTACIONAL DE TRÉBOL BLANCO (Trifolium repens L.)

The objective of the study was to evaluate the seasonal growth of the white clover (Trifolium repens L.) to determine the optimal moment for harvesting. A growth analysis per season was carried out in a four-year pasture established in Montecillo, Estado de México. The experimental plot was 9 m2, with eight treatments and three repetitions, under a completely random design. The treatments consisted in weekly cuts in a successive manner. The variables evaluated were: dry matter yield, botanical and morphological composition, leaf area index, growth rate, and intercepted radiation. The highest fodder yield was obtained in the eighth week for spring, fall and winter (2953, 1592 and 1790 kg DM ha-1) and in summer in the seventh with 1970 kg DM ha-1. The growth rate varied between seasons (p<0.05). The highest leaf area index was found on week five in summer (P<0.05). The leaf was the greatest component, except in the summer. The results indicate that the white clover should be harvested in the eighth week in spring, fall and winter, and in the seventh in summer.El objetivo del estudio fue evaluar el crecimiento estacional del trébol blanco (Trifolium repens L.) para determinar el momento óptimo de cosecha. Se realizó un análisis de crecimiento por estación en una pradera de cuatro años de establecida en Montecillo, Estado de México. La parcela experimental de 9 m2, con ocho tratamientos y tres repeticiones, bajo un diseño completamente al azar. Los tratamientos consistieron en cortes semanales de manera sucesiva. Las variables evaluadas fueron: rendimiento de materia seca, composición botánica y morfológica, índice de área foliar, tasa de crecimiento y radiación interceptada. El mayor rendimiento de forraje se obtuvo en la octava semana para primavera, otoño e invierno (2953, 1592 y 1790 kg MS ha-1) y en verano en la séptima con 1970 kg MS ha-1. La tasa de crecimiento varió entre estaciones (p<0.05). El mayor índice de área foliar se presentó a la semana cinco en verano (P<0.05). La hoja fue el mayor componente, a excepción del verano. Los resultados indican que el trébol blanco se debe cosechar en la octava semana en primavera, otoño e invierno y en la séptima en verano

Tropical Grass Growth Functions Modeling by Using Nonlinear Mixed Models

Nonlinear Growth curves are used for modeling plant physiological variables. These models are preferable because the polynomial coefficients of the equations have a biological significance. The response variables of the curves occurs commonly with repeated measurements over time and measurements are on different environments. The traditional statistical analysis does not include a repeated measures approach, which can lead to improper estimation of the error terms. It is important to study the growth of tropical grass (Da Silva and Carvalho 2005)

Occupational and Environmental Risks from Mancozeb in Aviation Facilities in the Banana Producing Area of Teapa, Tabasco, Mexico

Purpose: To identify occupational risks and practices in the four aerial fumigation facilities in the Sierra banana growing region and to evaluate environmental impacts from Mancozeb use.Methods: Occupational health risks were identified and practices in the four aerial fumigation facilities in the Sierra banana growing region were documented. Semi-structured interviews were conducted with installation managers. To evaluate environmental impact, samples of water and soil were collected and analysed in an acute toxicity bioassay with Vibrio fischeri, using uncontaminated soil and water to establish background levels.Results: Even in the largest and best-equipped facility, serious risks to workers’ health were encountered from inadequate use of protective equipment by workers. Furthermore, excessive use of pesticide, lack of re-use of unused product, poor facility design and poor use of wash-water were observed, resulting in  maximum toxicity of > 5 times background in discharged water. Parallel soil samples were > 20 times  more toxic than background, being most toxic at > 0.5 km from the discharge point.Conclusion: Areas of opportunity to improve worker health and the environment include proper and  consistent use of protective equipment, re-use of unused product, wastewater reduction and appropriate wastewater treatment.Keywords: Black Sigatoka, Ethylene thiourea, Fumigation, Pesticide, Mancozeb, Airports, Microtox, Vibrio fischeri, Occupational health risks, Toxicit

Efecto de residuos de amaranto (Amaranthus hypochondriacus L.) en el control de maleza y rendimiento de rábano, cebolla y zanahoria

Studies were conducted to evaluate the effect of dry residue of amaranth (Amaranthus hypochondriacus L. var. Azteca) stem on weed growth and yield of radish (Raphanus sativus L. var. Champion), onion (Allium cepa L. var. Cambray), and carrot (Daucus carota L. var. Nantes), in order to determine the inhibitory effect of amaranth. The treatments were established under field conditions: 1) aqueous extract (AE); 2) soil-incorporated residue (S-IR); 3) surface-applied residue (S-AR); 4) unaltered soil control (U-S/C); 5) soil-incorporated control (S-I/C). The soil type at the study site was loamy-sand, with bulk density 1.47 m–3, containing 2.1% organic matter. The species with the largest number of plants and highest dry weight in the three vegetables were Simsia amplexicaulis (Cav.) Pers., and a group of Gramineae grasses. Weed reduction was observed with treatments S-AR and S-IR related to the respective controls (U-S/C and S-I/C). Generally, decrease in plant number and dry weight in both treatments varied from 60% to 97% during the vegetable cycle. Radish yield decreased significantly with S-AR and S-IR; whereas that of onion and carrot increased significantly with S-AR. The results indicate that amaranth residue, incorporated or surface applied may control some weeds in radish, onion, and carrot. The surface-applied residue has potential to increase the yield of onion and carrot. However, it is necessary to find optimal residue management conditions for its application in the field to avoid reduction in yield of sensitive crops like radish, and/or when the residue is incorporated.El estudio se realizó para evaluar el efecto del residuo seco del tallo de amaranto (Amaranthus hypochondriacus L. var. Azteca) en el crecimiento de maleza y el rendimiento de rábano (Raphanus sativus L. var. Champion), cebolla (Allium cepa L. var. Cambray) y zanahoria (Daucus carota L. var. Nantes), para determinar el efecto inhibitorio del amaranto. Los tratamientos se establecieron en condiciones de campo: 1) extracto acuoso (EA); 2) residuo incorporado en el suelo (RI); 3) aplicación superficial del residuo (RS); 4) testigo sin alteración del suelo (TE-S/AS); 5) testigo con incorporación del suelo (TE-C/IS). El tipo de suelo en el sitio de estudio fue arenoso-migajoso, con densidad aparente de 1,47 m–3 y 2,1% de materia orgánica. Las especies con mayor número de plantas y mayor peso seco en las tres hortalizas fueron Simsia amplexicaulis (Cav.) Pers., y un grupo de gramíneas. Se observó disminución de maleza con los tratamientos RS y RI en relación con los testigos respectivos (TE-S/AS y TE-C/IS). De manera general, la disminución del número de plantas y peso seco en ambos tratamientos varió de 60% a 97%, durante el ciclo de las hortalizas. El rendimiento de rábano disminuyó significativamente con RS y RI; el rendimiento de cebolla y zanahoria aumentó significativamente con RS. Los resultados indican que el residuo de amaranto, incorporado o aplicado superficialmente, puede controlar maleza en rábano, cebolla y zanahoria. El residuo aplicado superficialmente tiene potencial para incrementar el rendimiento de cebolla y zanahoria, sin embargo, es necesario encontrar condiciones óptimas del manejo del residuo para su aplicación en campo y para evitar que disminuya el rendimiento de cultivos sensibles como el de rábano y/o cuando el residuo es incorporado

[Establishment and development of Tabebuia rosea (Bignoniaceae) seedlings in a semideciduous tropical forest under management, Pacific coast of Mexico]

We evaluated the effect of soil "scarification" and vegetation clearing treatments on the natural regeneration and initial development of Tabebuia rosea (Bertold) DC. seedlings in a moderate sized semideciduous tropical forest subjected to wood harvesting on the coast of Jalisco, Mexico. The treatments were applied under "seed" trees, and the number of germinated seedlings and their development were evaluated for nine months. Soil "scarification" promoted seed germination and initial seedling development, while the control of the competing vegetation increased the seedling growth and reduced their mortality. These results should be taken into account for the natural regeneration of this species, after clearing, to improve wood production, and should be incorporated into the silvicultural techniques currently developed in the region

Carcass characteristics, physicochemical changes and oxidative stress indicators of meat from sheep fed diets with coffee pulp

The purpose of this study was to determine how feeding sheep coffee pulp affects carcass characteristics and what changes occur in physicochemical, antioxidant capacity and oxidation of the meat during refrigerated storage. The experiment was carried out in 15 Blackbelly lambs weighing an average 22.86±0.76kg. The animals were assigned to three treatments: T0=control diet, T1=diet with 8% coffee pulp, and T2=diet with 16% coffee pulp. After fattening for 56 days, the sheep were slaughtered and the carcasses assessed. The inclusion of 16% coffee pulp in the diet increased carcass dressing from 48.19 to 50.83% and decreased the amount of fat in rumen and intestines from 3.43 to 2.53% (P<0.05). The inclusion of coffee pulp in the diet did not alter the amount of crude protein or fat in meat or its oxidation and antioxidant capacity during refrigerated storage. However, the inclusion of coffee pulp in the diet decreased fat in the rumen and intestines, and thus increased the amount of usable meat

Evaluación del impacto ambiental y productivo de proyectos de desarrollo tecnológico en el cultivo de trigo en México

48 páginasEl presente estudio de caso forma parte de un proyecto conjunto de ISNAR-BID y los institutos de investigación en el medio rural de seis países latinoamericano. El proyecto global está enfocado en el análisis de alternativas metodológicas para responder a las nuevas demandas tecnológicas de agroindustria y recursos naturales. La nueva realidad, caracterizada por la disminución en la regulación gubernamental, la integración comercial y por la incapacidad de expandir la frontera agrícola, obliga al sector agrícola a introducir por la incapacidad de expandir la frontera agrícola, obliga al sector agrícola a introducir cambios tecnológicos que armonicen la explotación racional de los recursos naturales, la competitividad, la seguridad alimentaria y una mejor distribución de los beneficios