Métodos de escarificación en semillas de Guaiacum coulteri, especie amenazada del bosque tropical caducifolio del norte de Sinaloa, México

This investigation documented the effect of methods of physical and chemical scarifi cation in seeds of Guaiacum coulteri, a species of tropical deciduous forest from Sinaloa protected by national and international laws, in order to contribute to the germinative knowledge of the species. For this, six pregerminative treatments were evaluated on the initial germination time (IGT), initial germination percentage (IGP), mean germination time (t50) and fi nal germination percentage (FGP) with a randomized completely design under laboratory conditions. Scarifi cation methods infl uenced signifi cantly (p<0.05) in the four variables. The seeds subjected to the treatments H2SO4 for 5 and 10 min started to germinate one day after sowing, whereas in the control occurred until the third day. The initial germination percentage increased to 73.3% with the treatment of sandpaper against the control that was just 10%. The scarifi cation with H2SO4 for 5 and 10 min advanced the mean germination time to 1.8 d, in relation with the control that was 5.2 d. The higher fi nal germination percentage was obtained with the sanding of the seeds (86.7%), unlike 51.1% achieved in hot water (60 °C) for 10 min. The knowledge derived from this essay demonstrated that the methods of scarifi cation with sandpaper and sulfuric acid were the best pregerminative treatments, due to they fragmented or weakened the seed coat and allowed obtaining high germination rates, what will have relevance for the production of seedlings.Esta investigación documentó el efecto de métodos de escarificación física y química en semillas de Guaiacum coulteri, especie del bosque tropical caducifolio sinaloense protegida por leyes mexicanas e internacionales, con la fi nalidad de contribuir a su conocimiento germinativo. Para ello se evaluaron seis tratamientos pregerminativos sobre el tiempo de inicio de germinación (TIG), porcentaje inicial de germinación (PIG), tiempo medio de germinación (t50) y porcentaje final de germinación (PFG) con un diseño completamente al azar bajo condiciones de laboratorio. Los métodos de escarificación influyeron de manera significativa (p<0,05) en las cuatro variables estudiadas. Las semillas sometidas a los tratamientos H2SO4 por 5 y 10 min iniciaron su germinación un día después de la siembra, mientras que en el testigo ocurrió hasta el tercer día. El porcentaje inicial de germinación se incrementó al 73,3% con el tratamiento de lija versus el testigo que fue de 10%. La escarificación con H2SO4 por 5 y 10 min adelantaron el t50 a los 1,8 d, en contraste con el testigo que fue a los 5,2 d. El mayor porcentaje final de germinación se obtuvo con el lijado de semillas (86,7%), a diferencia del 51,1% alcanzado en agua caliente (60 °C) durante 10 min. Los conocimientos derivados de este ensayo demostraron que los métodos de escarificación con lija y ácido sulfúrico fueron los mejores tratamientos pregerminativos, debido a que fragmentaron o debilitaron la testa de las semillas y permitieron obtener altas tasas de germinación, lo que tendrá relevancia para la producción de plántulas

Germinación diferencial asociada con viviparidad facultativa en Stenocereus thurberi (Cactaceae): correlaciones climáticas en poblaciones marginales de Sinaloa, México

Background and Aims: Precocious (viviparous) seed germination in fruits of Stenocereus thurberi has been correlated with higher germination rate of the remaining seeds. This study compares the germination of five populations from Sinaloa, Mexico, to determine: 1) whether there is a pattern associated with precocious seed germination and, 2) how much the viviparous phenomenon accounts for germination compared to variation between fruits, individuals and populations of the cactus.Methods: The incidence of vivipary was recorded in 194 plants, and seeds were separated into four putative sources of variance: populations, reproductive categories (VV: viviparous, NV: non-viviparous), individuals within categories and fruits within individuals. The seed germination response in percentage (PGF), mean time (TMG), rate (VG), and synchrony of germination (SG) was evaluated under a randomized complete blocks scheme with three replicates, in experimental units of 25 seeds. Data were analyzed with hierarchical ANOVAs for a linear mixed model.Key results: Reproductive categories accounted for 5-11% of variance and showed significant differences in favor of viviparous phenotypes, with PGF of 35 vs 19% and 91 vs 72%, VG of 1.5 vs 0.5 and 7.9 vs 5.4 seeds/day, and SG of 0.3 vs 0.1, 0.7 vs 0.5 and 0.8 vs 0.6. Buenavista and Tosalibampo populations showed higher percentage, rate and synchrony of germination than the other populations (P<0.05, Student t-test).Conclusions: There is a seed germination pattern associated to vivipary in S. thurberi. The variance accounted by this condition depends on the environment in which seed maturation and germination occur. The seeds from viviparous phenotypes showed higher germination vigor than seeds from non-viviparous plants, revealing potential for seedling recruitment and population growth under drought and salinity stress.Antecedentes y Objetivos: La germinación precoz (vivípara) de semillas en frutos de Stenocereus thurberi se ha correlacionado con mayor velocidad de germinación de las semillas remanentes. Esta investigación compara la germinación de cinco poblaciones de Sinaloa, México, para determinar: 1) si existe un patrón asociado con la germinación precoz de las semillas y 2) cuánto contribuye el fenómeno vivíparo a la germinación, dada la variación entre frutos, individuos y poblaciones de esta especie.Métodos: Se revisó el nivel de viviparidad de 194 plantas y se separaron las semillas en cuatro probables fuentes de varianza: poblaciones, categorías reproductivas (VV: vivíparas y NV: no vivíparas), plantas dentro de categorías y frutos dentro de plantas. Las respuestas de germinación final (PGF), tiempo medio (TMG), velocidad (VG) y sincronía de germinación (SG) se evaluaron en bloques al azar con tres repeticiones, en unidades experimentales de 25 semillas. Los datos se analizaron con ANOVA’s jerárquicos bajo un modelo lineal mixto.Resultados clave: Las categorías reproductivas explicaron 5-11% de la varianza y mostraron diferencias significativas a favor de las vivíparas, con PGF de 35 vs 19% y 91 vs 72%, VG de 1.5 vs 0.5 y 7.9 vs 5.4 semillas/día, y SG de 0.3 vs 0.1, 0.7 vs 0.5 y 0.8 vs 0.6. Las poblaciones de Buenavista y Tosalibampo tuvieron mayor porcentaje, velocidad y sincronía de germinación (prueba t de Student, P<0.05) que las otras poblaciones.Conclusiones: Existe un patrón de germinación asociado con viviparidad en S. thurberi. La varianza asociada con esta condición depende del ambiente de maduración y germinación de las semillas. Los fenotipos vivíparos germinaron con mayor vigor que los no vivíparos, mostrando potencial para apoyar la incorporación de individuos y el crecimiento de la población en condiciones de estrés hídrico y salino

Biostimulants on yield and its components in common bean (Phaseolus vulgaris L.)

Objective: Study the effect of biostimulants on yield and its components, in Higuera Azufrado beans in the northern Sinaloa.                Design/methodology/approach: Randomized complete block design, three replications, a common bean variety and five treatments (four biostimulants and one control). Evaluated variables: plant height and yield and its components.                           Results: Fia Kelp® biostimulant based on seaweed extract (Ascophyllum nodosum and Macrocystis pyrifera), was outstanding for increased in plant height, seed yield, number of seeds per pod and weight of 100 seeds.    Limitations on study/implications: The study was carried out only in one crop cycle, is necessary to continue evaluating the biostimulants used during more consecutive cycles, to prove their effect on the characters of aerial biomass, harvest index and number of pods per crop m2.     Findings/conclusions: Biostimulants foliar applications had a positive effect on seed yield and some of its components, with respect to the control. The number of normal pods per m2 was the variable that showed the highest percentage of yield with seed yield.                                  Keywords: plant nutrition, foliar application, sustainable production.Objective: To study the effect of biostimulants on yield and its components in Azufrado Higuera beans in northern Sinaloa. Design/Methodology/Approach: Randomized complete block design with three repetitions, a common bean variety, and five treatments (four biostimulants and one control). Assessed variables: plant height, yield, and its components. Results: The seaweed-based (Ascophyllum nodosum and Macrocystis pyrifera) Fia Kelp® biostimulant caused a remarkable increase in plant height, seed yield, number of seeds per pod, and 100-seed weight. Study Limitations/Implications: The study was carried out during a single crop cycle. Therefore, an ongoing assessment of the biostimulants used must be carried out during more consecutive cycles to prove their effect on the aerial biomass characteristics, harvest index, and number of pods per m2. Findings/Conclusions: Foliar application of biostimulants had a positive effect on seed yield and some of its components with respect to the control. The number of normal pods per m2 was the variable with the highest correlation percentage regarding seed yield

Morpho-physiological characteristics of corn (Zea mays L.) affected by drought during its vegetative stage

Objective: To evaluate the response corn hybrids have on their growth of aerial and root parts, transpiration,and water use efficiency during their early vegetative stage in irrigation and drought conditions.Design/methodology/approach: A randomized complete block design with a factorial arrangement, threerepetitions, three corn hybrids and two humidity levels were used. The evaluated variables were: plant height,leaf area, root length, dry weight of the aerial and root part of the plants, efficiency in the water use and totalplant transpiration.Results: The leaf area and dry weight data of the aerial parts of the assessed plants were greater in irrigationthan in drought; in contrast, root length, dry root weight and water use efficiency were higher in drought. SV 3245 registered a higher total transpiration per plant; SV 3243 and ASGROW 7543 showed higher dry weight in their aerial parts; ASGROW 7543 accumulated a greater dry weight at their roots and was more water usage efficient. The experiments indicated interaction for root length, dry root weight and efficiency in water use.Limitations on study/implications: The drought caused seedlings’ death at 28 days after sowing (dds), therefore, it was not possible to continue the evaluations from then on.Findings/conclusions: The drought decreased the growth of the aerial parts of the plants and increased the root system and efficiency in their water usage

Estructura y riqueza vegetal de las islas de la costa de Sinaloa, México.

Las islas continentales de Sinaloa difieren en forma, geología, topografía, clima y biología, por tanto pudieran ser varios los factores que determinan la composición y estructura de las comunidades vegetales que ahí habitan. Esta investigación, realizada en 16 islas del estado, tiene como objetivos: 1) ajustar modelos especies-área para evaluar la importancia de las variables biogeográficas en la predicción de la riqueza de especies vegetales, con base en muestreo de campo y datos publicados sobre la flora de cinco islas de la entidad, y 2) esclarecer las relaciones entre medio y vegetación en 16 islas, con ayuda de análisis multivariables de clasificación y ordenación. El modelo exponencial y la función potencial, dan valores de R2 entre 0.20 y 0.25, mientras que el modelo exponencial modificado [S = ln k + z (ln A)2], resultó apropiado por mostrar un poder predictivo del 96%-98% y error menor al 3% en el número de especies predichas. La clasificación formó seis grupos de sitios con 11 especies dominantes. En la ordenación de la vegetación, los tres primeros ejes del análisis de correspondencia linearizado explican 35.0% de la varianza total de las especies con λ = 0.793 para el primer eje y una longitud del gradiente de 4.835. El análisis de correspondencia canónico muestra una varianza acumulada en los tres primeros ejes de 32.3% y λ = 4.354. El primer eje es un gradiente relacionado con nitratos y pH, mientras que el segundo eje se correlaciona con calcio, fosfatos, cobertura de rocas, pendiente, profundidad, porcentaje de materia orgánica, arena y limo. Se concluye que el modelo propuesto [S = ln k + z (ln A)2] permite hacer estimaciones del número real de especies en las islas de Sinaloa y, los factores geomorfológicos y edáficos, son determinantes en la composición de las comunidades vegetales en las islas. _______________ STRUCTURE AND RICHNESS OF COMUNITIES VEGETATION THE ISLANDS OFF THE COAST OF SINALOA, MEXICO. ABSTRACT: The islands continental of Sinaloa differ in shape, geology, topograpy climate and biology, therefore could be several factors that determine the composition and structure of plant communities that live there. In this study, conducted in 16 islands of the state, aims to: 1) fit species-area models to assess the importance of biogeographical variables in the predicting of plant species richness, based on field sampling and previously published data about plant communities on the five islands off the state, and 2) clarify the relationship between environment and vegetation in the 16 islands, multivariate analysis using classification and ordination. The model exponential and power function, provided R2 values between 0.20 and 0.25, while the modified exponential model [S = ln k + z (ln A)2], was appropriate with predictive power of 96%-98% and with an error less than 3% in the number of species. In other results, the classification analysis formed six groups of sites whith 11 species are dominant. In the analysis of the vegetation by means ordination, the first 3 axes of detrended correspondence analysis explained 35.0% of the total variance of species with λ = 0.793 for the first DCA axis gradient length of 4835. The canonical correspondence analysis gives a accumulated variance in the first 3 axes of 32.3% and λ = 4354. The first CCA axis is a gradient related to nitrates and pH, while the second axis is related to calcium, phosphates, stone cover, ground slope, soil depth, percent organic matter, sand and silt. We conclude that the model [S = ln k + z (ln A)2] allows to estimate the actual number of species on the islands of Sinaloa, and geomorphological and edaphic factors are important in the structure and composition of plant communities in the islands.Tesis (Doctorado en Ciencias, especialista en Botánica).- Colegio de Postgraduados, 2012.Consejo Nacional de Ciencia y Tecnología (CONACyT). Fondos Mixtos de CONACyT y Gobierno del Estado de Sinaloa

Resistencia del frijol al ataque del gorgojo pardo Acanthoscelides obtectus (Say, 1831) (Coleoptera: Chrysomelidae) en la zona Norte de Sinaloa

El frijol es un producto básico en la alimentación de los mexicanos, pero su comercialización y establecimiento es afectado por el gorgojo pardo (A. obtectus), ya que es una plaga grave cuando la semilla está almacenada. En la última década, en Sinaloa, México, se establecieron nuevas variedades de fríjol con características agronómicas valiosas, como la alta productividad y calidad del producto cosechado; sin embargo, es indispensable determinar la resistencia o alta tolerancia de estos cultivares al ataque de este insecto. Debido a esto, se determinó la resistencia de seis cultivares de frijol (Aluyori, Azufrasin, Azufrado Higuera, Azufrado Noroeste, Azufrado Regional 87 y Janasa) cultivados en el centro y norte del estado de Sinaloa, al ataque y daño del gorgojo pardo Acanthoscelides obtectus (Say, 1831). Se compararon seis cultivares con cuatro repeticiones. El cultivar Aluyori presentó mayor resistencia con sólo el 18 % de semilla, escaso número de adultos emergidos (37) y mínima disminución de la capacidad germinativa (2.33 %). Por el contrario, el más susceptible fue Janasa con los siguientes valores: 51.75 %, 131.5 y 24.75 %, respectivamente. Por lo anterior, se recomienda la utilización de Aluyori y Azufrado Higuera para reducir el impacto negativo de la plaga, aunque se recomienda seguir con la experimentación de los materiales contenidos en los bancos de germoplasma para la futura liberación de nuevos cultivares.The bean is a basic product in the diet of Mexicans, but its commercialization and establishment is affected by the brown weevil (A. obtectus), since it is a serious pest when the seed is stored. In the last decade, in Sinaloa, Mexico, new bean varieties have been established with valuable agronomic characteristics, such as high productivity and quality of the harvested product; However, it is essential to determine the resistance or high tolerance of these cultivars to the attack of this insect. Due to this, the resistance of six bean cultivars (Aluyori, Azufrasin, Azufrado Higuera, Azufrado Noroeste, Azufrado Regional 87 and Janasa) cultivated in the center and north of the state of Sinaloa, to the attack and damage of the bean weevil Acanthoscelides obtectus (Say, 1831) was determined. Six cultivars with four replications were compared. The Aluyori cultivar presented greater resistance with only 18 % seed, low number of emerged adults (37) and minimal decrease in germination capacity (2.33 %). On the contrary, the most susceptible was Janasa with the following values: 51.75 %, 131.5 and 24.75 %, respectively. Therefore, the use of Aluyori and Azufrado Higuera is recommended to reduce the negative impact of the pest, although it is recommended to continue with the experimentation of the materials contained in the germplasm banks for the future release of new cultivars