ABSTRACT An important aspect in the study and understanding of the physical phenomena involved in water movement in the soil-plant system is the need to carry out the hydrodynamic characterization (HC) of non-saturated field soils. Studies of this type have been widely developed in soils of temperate climates, but they are infrequent in the tropics, hence there is a need for further research in tropical Vertisols under field conditions. Hydrodynamic characterization consists of finding the functional relationship between soil hydraulic conductivity (K), matric head (h) and soil moisture content (θ), widely known as K(θ) and h(θ) relationships, being the main objective of this study. The instantaneous profile method (IPM) was applied, in which splines were used for the HC of a bare, tropical agricultural field soil classified as a Vertisol. Field measurements of h and θ were made at five different soil depths (0.15, 0.30, 0.45, 0.60 and 0.90 m) and values of K at the same depths were estimated with the IPM, which allowed for the estimation of pairs of values of the K(θ) relationships in the soil profile. Unlike in other studies with the same objective, the use of splines was proposed to represent the spatial variation of the H(z) and θ(z) functions in the IPM. Subsequently, the van Genuchten equation was adjusted to the specific values determined for the h(θ) relations (r2 value ranged from 0.65 to 0.87), and the Ks values and the point data of K and θ were used to estimate the accuracy of the equation proposed by Mualem–van Genuchten (M-vG): in this case negative values for the exponent l of the M-vG function were determined for the five soil depths under study, ranging from –7.04 (0.45 m deep), to -13.26 (0.90 m deep). In addition, pedotransfer functions for tropical soils proposed in the literature, based on different soil physical properties, were used to estimate the h(θ) and K(θ) relationships and the saturated hydraulic conductivity (Ks). Best square root of the mean squared error (SRMSEθ) observed was 0.02853 cm3 cm-3 at 0.15 m depth and 0.02262 cm3 cm-3 at 0.9 m depth for h(θ) relations, and in all cases, the SRMSEk values are less than 0.0018 m day-1 for K(θ) relationships. The results reveal the utility of splines in the IPM for characterizing the soil profile K(θ) relationships in field studies, as well as the need for more research to the generation of pedotransfer functions in tropical Vertisols.

Resumen Con datos del Sistema de Información Agroalimentaria y Pesquera se caracteriza la productividad de maíz grano en el ámbito municipal de Campeche, México, mediante estadística multivariada, análisis espacial de la producción y aplicación de una encuesta a productores para así determinar los factores que condicionan la competitividad del sector en el interior del estado. A medida que se pasa del norte al sur del estado, el autoconsumo y empleo de semillas criollas para la siembra aumenta, por lo que se reduce la competitividad (beneficio/costo): Hopelchén (1.80, norte del estado), Champotón (1.38, centro) y Candelaria (0.97, sur). De acuerdo con la encuesta, se concluye que aspectos de sanidad, desorganización de productores y falta de esquemas de comercialización limitan la productividad de maíz en el estado.

Abstract With data from Agri-Food and Fisheries Information System, the productivity of grain maize in the state of Campeche was characterized at the municipal level, through multivariate statistics, spatial analysis of production and the application of a survey to farmers, to determine the factors that condition the competitiveness of the sector within the state. It was found that as one moves from the north to the south of the state, self-consumption and use of native seeds for sowing increases; which reduces competitiveness (benefit/cost): Hopelchén (1.80, north of the state), Champotón (1.38, center) and Candelaria (0.97, south). According to the survey carried, it was concluded that aspects of agricultural health, disorganization of farmers and lack of commercialization schemes, limit the productivity of corn in the state.

ABSTRACT The presence of gastrointestinal nematodes (GIN) in sheep is a low productivity cause. This study aimed to determine the in vitro efficiency of Gliricidia sepium, Leucaena leucocephala, Guazuma ulmifolia, and Bursera simaruba aqueous extracts at three different doses (0.75, 1.00, and 1.25 mL), inhibiting the egg hatching of GIN from sheep. The inhibition efficiency in egg hatching (IEH), larval identification, and its genera proportion were evaluated. Analysis of data was performed using Chi-square tests and analysis of variance. The four extracts obtained an IEH of 50%, being similar (p > 0.05) between them. The 1.25 mL dose and its combinations of Leucaena leucocephala and Gliricidia sepium at 1.25 mL dose obtained the highest efficiency (68.0, 85.0, and 77.0%, respectively). Five genera of larva were identified (Haemonchus spp, Trichostrongylus spp, Oesophagostomum spp, Cooperia spp, and Nematodirus spp). The highest prevalence (p ≤ 0.05) was obtained by Haemonchus spp (58.0%). According to the results, the four aqueous extracts exhibited ovicidal activity (GIN). However, the 1.25 mL dose and the Leucaena leucocephala, Gliricidia sepium extracts at 1.25 mL doses were the most effective.

RESUMEN: La alta presencia de nematodos gastrointestinales (ngi) en ovinos, es una causa de baja productividad. El objetivo fue determinar de forma preliminar la eficiencia in vitro de extractos acuosos de Gliricidia sepium, Leucaena leucocephala, Guazuma ulmifolia y Bursera simaruba a tres dosis (0.75, 1.00 y 1.25 mL), en la inhibición de la eclosión de huevos de ngi de ovinos. Se evaluó la eficiencia de inhibición en la eclosión de huevos (EIH), identificación y proporción de géneros de larvas. El análisis de datos se realizó mediante pruebas de Chi cuadrada y análisis de varianza. Los cuatro extractos obtuvieron una EIH del 50%, siendo similares (p > 0.05) entre ellos. La dosis de 1.25 mL y las combinaciones de Leucaena leucocephala y Gliricidia sepium a dosis de 1.25 mL obtuvieron mayor eficiencia (68.0, 85.0 y 77.0%, respectivamente). Se identificaron cinco géneros de larvas (Haemonchus spp., Trichostrongylus spp., Oesophagostomum spp., Cooperia spp., y Nematodirus spp.), siendo el de mayor (p ≤ 0.05) prevalencia Haemonchus spp. (58.0%). Los cuatro extractos acuosos exhibieron actividad ovicida de ngi. No obstante, la dosis de 1.25 mL y los extractos de Leucaena leucocephala, Gliricidia sepium a dosis de 1.25 mL fueron los más eficaces.

Abstract The inoculation with arbuscular mycorrhizal fungi has allowed a controlled development and growth in horticultural species; however, its effect has not been evaluated in some tropical ornamental crops such as heliconias. The objective was to evaluate the application of arbuscular mycorrhizal fungi (AMF) in the development of Heliconia stricta, taking as a general hypothesis that the use of AMF increases the absorption of nutrients such as nitrogen, phosphorus, potassium and favor their acclimatization and growth. The physiological development of H. stricta plants was evaluated in response to their inoculation with four AMF: Rhizophagus intraradices, Zac-19, mixture of strains and native inoculum in Mexico. The height of the plants, number of buds, photosynthetic rate with an IRGA photosynthesis analyzer, LI-COR 6400XT and mycorrhizal colonization by the Phillips and Hayman method were determined. The results showed statistically significant increases due to the effect of the non-native inoculum, on the height of the plant, the number of buds per plant, the photosynthetic rate and mycorrhizal colonization (p≤ 0.05). The native inoculum produced statistically significant effects on the colonization of the roots (p≤ 0.05). It is concluded that there is a statistically significant beneficial effect (p≤ 0.05) of the mycorrhizal inoculation on the growth of the plants due to its higher height, number of buds per plant and photosynthetic rate.

Resumen La inoculación con hongos micorrízicos arbusculares ha permitido un desarrollo y crecimiento controlado en especies hortícolas; sin embargo, no se ha evaluado su efecto en algunos cultivos ornamentales tropicales como las heliconias. El objetivo fue evaluar la aplicación de hongos micorrízicos arbusculares (HMA) en el desarrollo de Heliconia stricta, teniendo como hipótesis general que el uso de HMA incrementa la absorción de nutrientes como nitrógeno, fósforo, potasio y favorecer su aclimatación y crecimiento. Se evaluó el desarrollo fisiológico de las plantas de H. stricta como respuesta a su inoculación con cuatro HMA: Rhizophagus intraradices, Zac-19, mezcla de cepas e inóculo nativo en México. Se determinó la altura de las plantas, número de brotes, tasa fotosintética con un analizador de fotosíntesis IRGA, LI-COR 6400XT y colonización micorrízica por el método de Phillips y Hayman. Los resultados evidenciaron incrementos estadísticamente significativos por efecto del inóculo no nativo, en la altura de la planta, el número de brotes por planta, la tasa fotosintética y la colonización micorrízica (p≤ 0.05). El inóculo nativo produjo efectos estadísticamente significativos en la colonización de las raíces (p≤ 0.05). Se concluye que existe un efecto benéfico estadísticamente significativo (p≤ 0.05) de la inoculación micorrízica sobre el crecimiento de las plantas debido a su mayor altura, número de brotes por planta y tasa fotosintética.