Genotypes of Cenchrus ciliaris L., from Africa (CGIAR-ILRI, Ethiopia), were evaluated for cold tolerance and the ones with higher adaptation, were characterized by forage attributes: morphology, cytology, nutritional value and compared with commercial variety "Frio". Data were taken to forage maturity, in one cut and analyzed by principal components (CP), hierarchical cluster and analysis of variance. Tetraploid and cold, pentaploid, 2n= 5x= 45 genotypes were selected. The first three components explained 79% of the variation; CP1, 49%; CP2, 22%; and CP3, 9%. CP1 included: plant height, inflorescence length, forage height, FDA, lignin, total PC andl MS; CP2, leave MS, in vitro digestibility (DIVMS) and leaf: stem ratio. Plant height, forage height, stem diameter, inflorescence length and total MS positively correlated (p <0.05) with FDN, FDA and lignin, but negatively, with PC and DIVMS. Three groups were formed: G-1, five genotypes associated to MS yield and negatively to MS quality; G-2, B7 and B-Frio, were associated to forage quality; G-3, isolated genotype, with characteristics associated to inflorescence. There are materials that combine cold resistance and forage quality for the Chihuahuan Desert.

Genotipos de Cenchrus ciliaris L., de África (CGIAR-ILRI; Etiopía), se evaluaron para tolerancia al frío y los de mayor adaptación, se caracterizaron por atributos forrajeros colaterales: morfología, citología, valor nutritivo y se compararon con el cultivar comercial "Frío". Los datos se tomaron a la madurez del forraje, en un solo corte y se analizaron por componentes principales (CP), conglomerados jerárquicos y análisis de varianza. Los genotipos seleccionados fueron tetraploides y frío, pentaploide, 2n= 5x= 45. Los tres primeros componentes explicaron 79% de la variación; el CP1, 49%; CP2, 22%; y CP3, 9%. El CP 1 incluyó: altura de planta, longitud de inflorescencia, altura de forraje, FDA, lignina, PC y MS total; CP2, MS de hoja, digestibilidad in vitro (DIVMS) y relación hoja: tallo. Altura de planta, altura de forraje, diámetro de tallo, longitud de inflorescencia y MS total, correlacionaron positivamente (p< 0.05) con FDN, FDA y lignina, pero, negativamente, con PC y DIVMS. Se conformaron tres grupos: G-1, cinco genotipos asociados a rendimiento de MS y negativamente con calidad de MS; G-2, B7 y B-Frío, se asociaron a calidad de forraje; G-3, genotipo aislado, con atributos asociados a inflorescencia. Existen materiales que combinan resistencia a frío y calidad de forraje para el Desierto Chihuahuense.

The aim of the study was to detect the motivational profiles of high school students of Physical Education (PE) according to the teacher's discipline strategies and to analyze the relationships between the clusters and the motivational atmosphere, goal guidelines and satisfaction with lessons. A sample of 2002 students (970 male students and 1032 female students) was used. The instruments used were the Spanish versions of the scales: Strategies to Sustain Discipline Scale, Learning and Performance Orientations in Physical Education Classes Questionnaire, Perception of Success Questionnaire and Sport Satisfaction Instrument. A cluster analysis was applied revealing three motivational profiles, one of them with emphasis on self-determined strategies to maintain discipline in class and the other two profiles with emphasis on non-self- determined-strategies. Profiles were determined according to the number of hours of exercise practiced in a week. The self-determined strategies cluster consists mainly of women, and the non- self-determined clusters were composed of men. In the self-determined strategies cluster, we can find the largest number of students who practice two or more hours of physical exercise per week in their free time. To improve the classroom environment and reduce indiscipline behaviors, the teacher should use discipline strategies founded on intrinsic reasons for concern and responsibility.

El objetivo del estudio fue analizar las diferencias motivacionales del alumnado en las clases de Educación Física, según las estrategias de disciplina del profesor y analizar las relaciones de los conglomerados con el clima motivacional, orientaciones de meta y satisfacción. Participaron 2002 alumnos (970 varones y 1032 mujeres) de educación secundaria de entre 12-19 años. Como instrumentos se utilizaron la versión española de: Strategies to Sustain Discipline Scale, Learning and Performance Orientations in Physical Education Classes Questionnaire, Perception of Success Questionnaire y Sport Satisfaction Instrument. Se realizó un análisis de conglomerados que reveló tres perfiles de disciplina: uno con énfasis en estrategias autodeterminadas para mantener la disciplina en clase y dos con énfasis en estrategias no autodeterminadas Se hallaron el nº de horas semanales que practican ejercicio físico en su tiempo libre en función del perfil. El conglomerado de estrategias autodeterminadas está compuesto fundamentalmente por mujeres y los no autodeterminados por varones. En el de estrategias autodeterminadas se ubica el mayor número de estudiantes que practican dos o más horas semanales de ejercicio físico. Para mejorar el ambiente de clase y reducir las conductas de indisciplina, se deberían utilizar estrategias de disciplina fundamentadas en razones intrínsecas, de preocupación y responsabilidad.

O objetivo deste estudo foi analisar as propriedades psicométricas do Sport Satisfation Instrument (SSI) adaptado para a Educação Física (EF) por meio de uma análise fatorial exploratória da estrutura bidimensional do instrumento em uma amostra espanhola. Com isso, buscou-se determinar, de maneira preliminar, se o SSI constitui um instrumento válido e fiável para ser utilizado em futuras pesquisas. O instrumento foi elaborado em um modelo teórico de dois fatores: Satisfação/Diversão e Tédio. A amostra constituiu-se de um total de 224 alunos de secundária entre 12 e 19 anos. A versão [espanhola] do instrumento adaptado para a EF demonstrou níveis aceitáveis de consistência interna.

The objective of this study was to analyze the psychometric properties of Sport Satisfaction Instrument (SSI) adapted physical education (PE) using exploratory factor analysis of the dimensional structure of the instrument in a Spanish sample. It was intended to determine, on a preliminary basis, whether it constitutes a valid and reliable for use in future research. Was administered to a total of 224 high school students 12 to 19 years. This analysis supports the hypothesized theoretical model of two factors (satisfaction / fun and boredom). The Spanish version of the instrument for PE showed acceptable levels of internal consistency.

The objective was evaluating the effect of plant spacing on seed yield and quality in Bracchiaria brizantha cv. Marandú. The experiment was carried out in rain fed conditions in 2007 at the Universidad de Papaloapan, Loma Bonita, Oaxaca, Mexico. Six plant distances (broadcast, 25*25 cm, 50*50 cm, 75*75 cm, 100*100 cm and 125*125 cm between rows and plants, respectively) were assessed. To that end, a completely randomized block design with four replicates was set. The following variables were analyzed: pure seed yield (PSY), pure germinable seed yield (GPSY), number of panicles per m-2, panicle length, seed harvested per panicle, 1,000 seed weight, spikelet abscission rate, seed purity and germination. PSY and GPSY showed differences among treatments (P<0.01) and the highest values (47,8 and 11.0 kg ha-¹, respectively) were obtained at the 25*25 cm spacing. Panicle length, number of seed harvested in each panicle, 1,000 seed weight, seed purity and spikelet abscission rate also showed differences among treatments (P<0.05). Seed purity was the variable more closely linked to PSY and PGSY, showing r values of 0.81 and 0.55, respectively. Plant spacing did not influence germination rate (P>0.05). As a conclusion, it can be stated that the largest seed yield was obtained at the 25*25 cm spacing between rows and plants, respectively. Seed germination did not improve in any of the treatments being assessed.

El objetivo fue evaluar el efecto de la distancia entre plantas en el rendimiento y calidad de semilla de Brachiaria brizantha cv. Marandu. El experimento se realizó en temporal durante 2007, en la Universidad del Papaloapan, Loma Bonita, Oaxaca. Se evaluaron seis distancias entre plantas (voleo, 25 x 25, 50 x 50, 75 x 75, 100 x 100 y 125 x 125 cm entre líneas y plantas, respectivamente), con un diseño de bloques completos al azar, con cuatro repeticiones. Se midió el rendimiento de semilla pura (RSP), rendimiento de semilla pura germinable (RSPG), número de panículas m-2, longitud de panícula, número de semillas cosechadas por panícula, peso de 1,000 semillas, porcentaje de dehiscencia, semilla pura y germinación. El RSP y RSPG varió entre tratamientos (P<0.01), donde los mayores valores (47.8 y 11.0 kg ha-1, respectivamente) ocurrieron con la distancia 25 x 25 cm. La longitud de panícula, número de semillas cosechadas por panícula, peso de 1,000 semillas, porcentaje de semilla pura y dehiscencia de la semilla presentaron diferencias entre tratamientos (P<0.05). El porcentaje de semilla pura fue el componente con mayor grado de asociación con el RSP y RSPG, con valores de 0.81 y 0.55, respectivamente. El porcentaje de germinación no fue afectado por la distancia entre plantas (P>0.05). Se concluye que el mayor rendimiento de semilla de B. brizantha cv. Marandu, se logró con la distancia 25 x 25 cm entre líneas y plantas, respectivamente. La germinación de la semilla no fue mejorada por ninguno de los tratamientos evaluados.