RESUMO

La Educación Física, en la actualidad, presta cada vez más atención al desarrollo de estrategias pedagógicas, con la finalidad de perfeccionar los logros del aprendizaje y que este sea sostenible y enfrenta muchos retos de cómo acceder y mantener, en cualquier edad de la vida, la participación de experiencias de aprendizaje estimulantes. El objetivo de este trabajo fue desarrollar un estudio comparativo entre dos grupos de estudiantes para evaluar la calidad del proceso de enseñanza-aprendizaje, de la Educación Física, basado en la diferencia entre la clase presencial y la clase a distancia, demostrado en los resultados académicos. La investigación fue desarrollada con enfoque cuantitativo y diseño cuasiexperimental con prestest y postest, participaron estudiantes de educación básica regular del cuarto grado, en el año 2020 y de quinto grado durante el año 2021. La prueba de hipótesis determinó que la diferencia de los promedios fue significativa, durante el año 2020 fue de 14,5 y en el año 2021, de 13,5 para 0,05. Se obtuvo el rechazo de la hipótesis nula (Sig<0,05) y se aprobó la hipótesis alterna; lo que evidenció que en el periodo de confinamiento por la pandemia del COVID-19, los promedios en el área de Educación Física disminuyeron.

A Educação Física, atualmente, dá cada vez mais atenção ao desenvolvimento de estratégias pedagógicas, com o objetivo de aperfeiçoar as conquistas da aprendizagem e torná-la sustentável e enfrenta muitos desafios de como acessar e manter, em qualquer idade da vida, o envolvimento em experiências de aprendizagem estimulantes. . O objetivo deste trabalho foi desenvolver um estudo comparativo entre dois grupos de alunos para avaliar a qualidade do processo de ensino-aprendizagem da Educação Física, a partir da diferença entre a aula presencial e a aula a distância, demonstrada no resultados acadêmicos. . A pesquisa foi desenvolvida com abordagem quantitativa e delineamento quase-experimental com pré-teste e pós-teste, participaram alunos do ensino fundamental regular da quarta série no ano de 2020 e da quinta série durante o ano de 2021. O teste de hipótese determinou que a diferença na médias foi significativa, durante o ano de 2020 foi de 14,5 e em 2021, de 13,5 para 0,05. A hipótese nula foi rejeitada (Sig<0,05) e a hipótese alternativa foi aprovada; que mostrou que no período de confinamento devido à pandemia de COVID-19, as médias na área da Educação Física diminuíram.

Physical Education, currently, pays more and more attention to the development of pedagogical strategies, with the aim of perfecting learning achievements and making it sustainable and faces many challenges of how to access and maintain, at any age of life, engaging in stimulating learning experiences. The objective of this work was to carry out a comparative study between two groups of students to evaluate the quality of the teaching-learning process of Physical Education, based on the difference between the face-to-face class and the distance class, demonstrated in the academic results. The research was developed with a quantitative approach and quasi-experimental design with pretest and posttest, regular basic education students from the fourth grade in the year 2020 and from the fifth grade during the year 2021 participated. The hypothesis test determined that the difference in the averages was significant, during the year 2020 it was 14.5 and in 2021, from 13.5 to 0.05. The null hypothesis was rejected (Sig <0.05) and the alternative hypothesis was approved; which showed that in the period of confinement due to the COVID-19 pandemic, the averages in the area of Physical Education decreased.

RESUMO

To increase maize (Zea mays L.) yields in drought-prone environments and offset predicted maize yield losses under future climates, the development of improved breeding pipelines using a multi-disciplinary approach is essential. Elucidating key growth processes will provide opportunities to improve drought breeding progress through the identification of key phenotypic traits, ideotypes, and donors. In this study, we tested a large set of tropical and subtropical maize inbreds and single cross hybrids under reproductive stage drought stress and well-watered conditions. Patterns of biomass production, senescence, and plant water status were measured throughout the crop cycle. Under drought stress, early biomass production prior to anthesis was important for inbred yield, while delayed senescence was important for hybrid yield. Under well-watered conditions, the ability to maintain a high biomass throughout the growing cycle was crucial for inbred yield, while a stay-green pattern was important for hybrid yield. While new quantitative phenotyping tools such as spectral reflectance (Normalized Difference Vegetation Index, NDVI) allowed for the characterization of growth and senescence patterns as well as yield, qualitative measurements of canopy senescence were also found to be associated with grain yield.

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The oxygen isotope composition (δ(18)O), accumulation of minerals (ash content), and nitrogen (N) content in plant tissues have been recently proposed as useful integrative physiological criteria associated with yield potential and drought resistance in maize. This study tested the ability of near-infrared reflectance spectroscopy (NIRS) to predict δ(18)O and ash and N contents in leaves and mature kernels of maize. The δ(18)O and ash and N contents were determined in leaf and kernel samples from a set of 15 inbreds and 18 hybrids grown in Mexico under full irrigation and two levels of drought stress. Calibration models between NIRS spectra and the measured variables were developed using modified partial least-squares regressions. Global models (which included inbred lines and hybrids) accurately predicted ash and N contents, whereas prediction of δ(18)O showed lower results. Moreover, in hybrids, NIRS clearly reflected genotypic differences in leaf and kernel ash and N contents within each water treatment. It was concluded that NIRS can be used as a rapid, cost-effective, and accurate method for predicting ash and N contents and as a method for screening δ(18)O in maize with promising applications in crop management and maize breeding programs for improved water and nitrogen use efficiency and grain quality.

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SUMMARY: *Heterosis increases yield potential and improves adaptation to stress in maize (Zea mays); however, the underlying mechanisms remain elusive. *A set of tropical inbred lines and their hybrids were grown in the field for 2 yr under three different water regimes. First-year plant water use was evaluated by measuring instantaneous traits (stomatal conductance (g(s)) and steady-state chlorophyll fluorescence (F(s))) in individual leaves together with time-integrative traits, which included mineral accumulation in the whole leaves of plants and oxygen isotope enrichment above source water (Delta(18)O) and carbon isotope discrimination (Delta(13)C) in the same pooled leaves and in mature kernels. Second-year water use was evaluated by measuring leaf temperature, g(s) and relative water content (RWC). *Within each growing condition, hybrids showed higher F(s), mineral accumulation, RWC, and lower leaf temperature, Delta(18)O and Delta(13)C than inbred lines. Therefore, hybrids had a better water status than inbred lines, regardless of the water conditions. Differences in grain yield across growing conditions were explained by differences in water-use traits, with hybrids and inbred lines following a common pattern. Within each growing condition, most variations in grain yield, between hybrids and inbred lines, were also explained by differences in plant water-use traits. *Heterosis in tropical maize seems to be mediated by improved water use, irrespective of the water conditions during growth.

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