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.

ABSTRACT. Cowpea beans are an important legume whose primary consumption is in dry grains, although immature pods rich in protein, vitamins, fiber, minerals and antioxidants are sometimes included. The objective was to determine the nutritional and nutraceutical quality of 13 accessions of cowpea beans (Vigna unguiculata [L.] Walp.) grown in the Yucatan Peninsula. The study was carried out under greenhouse conditions, under a completely randomized design. The moisture content, ash, fat, crude protein (CP), fiber, carbohydrates, length and weight of pods, mineral content, total phenols (TP) and antioxidant capacity (AC) were determined by the ABTS method and DPPH. The accessions HEC02, OXC05, JMM09, JMM10 and JAL14 stood out for presenting the longest length and weight of the pods. Accessions OXC04 and CHE06 excelled in ash content (8.48%), moisture (18.24%), CP (23.32%) and fiber (20.11%). In the mineral content, the HEC02 accession obtained the highest levels of K, Ca and Mg. Regarding the content of nutraceuticals, the HAL14 collection presented the highest values of TP (18.02 mg g-1 EAG ps) and CA for DPPH (6.19 mg Trolox 100 g-1 ps) and ABTS (4.95 mg Trolox 100 g-1 ps). The variability between accessions suggests that CHE06 due to its levels of protein and crude fiber, and HEC02 due to its high mineral content could offer nutritional advantages, while the HAL14 accession could be considered the accession with the best nutraceutical quality.

RESUMEN. El frijol caupí es una importante leguminosa cuyo consumo primario es en granos secos, aunque en ocasiones se incluyen las vainas inmaduras ricas en proteínas, vitaminas, fibra, minerales y antioxidantes. El objetivo fue determinar la calidad nutrimental y nutracéutica de 13 accesiones de ejotes de caupí (Vigna unguiculata [L.] Walp.) cultivados en la Península de Yucatán. El estudio se llevó a cabo en condiciones de invernadero, bajo un diseño completamente al azar. Se determinó el contenido de humedad, cenizas, grasa, proteína, fibra cruda (PC), carbohidratos, longitud y peso de las vainas, contenido de minerales, fenoles totales (FT) y la capacidad antioxidante (CA) por el método de ABTS y DPPH. Las accesiones HEC02, OXC05, JMM09, JMM10 y JAL14 destacaron por presentar la mayor longitud y peso de las vainas. Las accesiones OXC04 y CHE06 sobresalieron en contenido de cenizas (8.48%), humedad (18.24%), PC (23.32%) y fibra (20.11%). Para el contenido de minerales, la accesión HEC02 tuvo los mayores niveles de K, Ca y Mg. Respecto al contenido de nutracéuticos, la colecta HAL14 presentó los mayores valores de FT (18.02 mg g-1 EAG ps) y CA para DPPH (6.19 mg Trolox 100 g-1 ps) y ABTS (4.95 mg Trolox 100 g-1 ps). La variabilidad entre accesiones, sugiere que CHE06 por sus niveles de proteína y fibra cruda y HEC02 por su alto contenido de minerales podrían ofrecer ventajas nutricionales, mientras que la accesión HAL14 podría considerarse la accesión con la mejor calidad nutracéutica.

The cowpea (Vigna unguiculata (L) Walp) is an important crop in several regions of the world, but in Mexico it is little used. The characterization of agricultural varieties has been based on morphological descriptors, including seed shape, color and size, as well as quantitative attributes such as mineral content. The aim of this research was to evaluate the morphological and nutritional characteristics of cowpea genotypes from the Yucatan Peninsula, Mexico. Fifteen collections were made from October 2017 to January 2018 and then evaluated for three qualitative morphological variables and 10 quantitative ones. The content of potassium, calcium, manganese, iron and zinc was determined by means of micro X-ray fluorescence. An analysis of variance and principal components were performed. Eighty percent of the collections have an ovoid shape, 73% a smooth to rough texture and 80% are black. In the quantitative morphological variables, 53% of the collections were considered to have small seeds, 40% medium and 7% large. The length, width and thickness of the genotypes were from 6.26 to 9.56, 3.64 to 7.48 and 2.86 to 5.56 mm, respectively, and the PET15 collection was the smallest. For mineral content, the OXC04 collection had the highest concentration of Ca, Mn, Fe and Zn, while the PET07 collection had the highest K content. There are high levels of phenotypic diversity in the collections studied and they are grouped based on their physical characteristics and not on their place of origin.

RESUMEN El frijol caupí (Vigna unguiculata (L) Walp) es un cultivo importante en varias regiones del mundo, pero en México no es muy explotado. La caracterización de variedades agrícolas se ha basado en descriptores morfológicos, en los que se incluyen: forma, color y tamaño de semilla, además de atributos cuantitativos como el contenido mineral. El objetivo del trabajo fue evaluar las características morfológicas y nutricionales de genotipos de frijol caupí de la Península de Yucatán, México. Se realizaron 15 colectas de octubre 2017 a enero 2018, a las que se evaluaron tres variables morfológicas cualitativas, 10 variables cuantitativas y se determinó el contenido de potasio, calcio, manganeso, hierro y zinc, mediante µ-fluorescencia de rayos-X. A los datos se les realizó un análisis de varianza y de componentes principales. El 80% de las colectas tienen forma ovoide, 73% textura suave a áspera y el 80% son de color negro. En las variables morfológicas cuantitativas, 53% de las colectas se consideran pequeñas, 40% medianas y 7% semillas grandes. La longitud, ancho y espesor de los genotipos fue de 6.26 a 9.56, 3.64 a 7.48 y de 2.86 a 5.56 mm, respectivamente, la colecta PET15 fue la de menor dimensión. Para el contenido mineral, la colecta OXC04 tuvo la mayor concentración de Ca, Mn, Fe y Zn, mientras que la colecta PET07 presentó mayor contenido de K. Hay altos niveles de diversidad fenotípica en las colectas estudiadas y se agrupan con base en sus características físicas y no al lugar de origen.

ABSTRACT The objective was to evaluate the effect of time and temperature of storage in the physiological Habanero pepper seed. The factors studied were: a) Seed Habanero (varieties H-244, H-243, H-259, H-228, H-256); b) Storage temperature (10 °C and 26 °C); c) Storage time (three, six and nine months). The treatments were organizated in a randomized factorial design. The results indicate after three months of seed storage under controlled conditions still have immature seeds and nine months the seed viability disrepaired. The storage seed for six months at 26 °C, ensures greater percentage of standard germination and yielded greater number of normal seedlings of the Habanero varieties H-228 and H-259.

RESUMEN El objetivo del presente estudio consistió en evaluar el efecto del tiempo y la temperatura de almacenamiento de la semilla de chile Habanero en la germinación estándar total y vigor de la semilla. Los factores estudiados fueron: a) Variedades de semilla de chile habanero (H-244, H-243, H-259, H-228, H-256); b) Temperatura de almacenamiento (10 °C y 26 °C) y; c) Tiempo de almacenamiento (tres, seis y nueve meses). Los tratamientos fueron organizados en las cámaras germinadoras bajo un diseño completamente al azar, con arreglo factorial. Los resultados indican que, a los tres meses de almacenamiento en condiciones controladas, las semillas se mantuvieron inmaduras y, a los nueve meses, se deterioran y pierden viabilidad. Almacenar la semilla de chile Habanero por seis meses a 26 °C, garantiza mayor porcentaje de germinación estándar total y permite obtener mayor número de plántulas normales de las variedades H-228 y H-259.

Abstract Background: Understanding the genetic structure of wild relatives of domesticated species is crucial for its conservation and to elucidate the sites of crop domestication. Lima bean is one of the five domesticated Phaseolus species and Mexico is one of its centers of domestication. Recent studies showed the existence of two wild gene pools (MI and MII) of this species in Mexico and suggested that their genetic divergence occurred in southeast Mexico. Question: Did MI and MII groups diverged around the Isthmus of Tehuantepec, Mexico? Studied species: Lima bean: Neotropical plant species, herbaceous, with an annual/short life cycle and with autogamous tendency. Study site and years of study: Seven wild populations were collected in 2012 in the State of Chiapas, México, area underrepresented in previous studies. Methods: Genetic diversity and grouping patterns of collected populations and their relationship to MI and MII groups were analyzed at eight microsatellite loci. Results: High genetic structure (FST: 0.42 to 0.96) and a high level of genetic diversity (HE = 0.48) were found. The analyses, and presence of admixed populations in MI and MII, suggested that the genetic divergence of these groups is an ongoing process centered around the Isthmus of Tehuantepec. Conclusions: Our results support the hypothesis that MI and MII groups diverged around the Isthmus of Tehuantepec; however, sampling should be increased both at population and genomic levels, to determine the precise organization of the genetic diversity of wild P. lunatus from Mexico.

Resumen Antecedentes: Entender la estructura genética de los parientes silvestres de las especies domesticadas es crucial para su conservación y para elucidar los sitios de domesticación de los cultivos. El frijol Lima es una de las cinco especies domesticadas del género Phaseolus y México es uno de sus centros de domesticación. Estudios recientes señalaron dos acervos genéticos silvestres (MI y MII) en México y sugirieron que su divergencia ocurrió en el sureste de México. Pregunta: ¿Los grupos silvestres MI y MII divergieron alrededor del Istmo de Tehuantepec, México? Especie en estudio: El frijol Lima es una especie Neotropical, herbácea, con ciclo de vida anual/corto y tendencia autógama. Sitio y años de estudio: Siete poblaciones silvestres fueron colectadas en 2012 en el Estado de Chiapas, México, área que fue subrepresentada en estudios previos. Métodos: Se analizó la diversidad genética y los patrones de agrupamiento de las poblaciones colectadas y su relación con los grupos MI and MII, usando ocho loci de microsatélites. Resultados: Se encontró una estructura genética alta (FST: 0.42 a 0.96) y niveles altos de diversidad genética (HE = 0.48). Los análisis y la presencia de poblaciones mezcladas en MI y MII sugieren que la divergencia de estos grupos aun continua alrededor del Istmo de Tehuantepec. Conclusiones: Nuestros resultados apoyan la hipótesis de que MI y MII divergieron alrededor del Istmo de Tehuantepec; sin embargo, hay que incrementar el muestreo, tanto a nivel genómico como poblacional, para determinar la organización precisa de la diversidad genética de P. lunatus silvestre en México.