Efeito do sombreamento artificial no crescimento e produtividade da soja - DOI:10.5039/agraria.v14i4a6876

When the premise is the best final use of wood, evaluation of anatomical variables is recommended, bearing in mind that they are correlated with the properties of this material. The present study aimed to evaluate the correlation between anatomy and the physical properties of wood from Parapiptadenia rigida (Benth.) Brenan, Peltophorum dubium (Spreng.) Taub., Eucalyptus grandis W. Hill × Eucalyptus urophylla S.T. Blake (hybrid) and Schizolobium parahyba (Vell.) Blake, from an agroforestry system. For this purpose, five trees of each species, aged 9 years old, were selected, and samples were collected from the diameter at 1.30 m height from the ground for analysis of the anatomical characteristics and physical properties of the wood. Anatomical variables, with the exception of fiber length and cell wall thickness, correlated with the physical properties of wood and influenced their values. The higher the cell wall fraction (0.79), vessel frequency (0.44) and ray frequency (0.92), the greater the basic density of the wood. The greater the fiber diameter (0.94), lumen diameter (0.88), vessel diameter (0.88), ray height (0.86) and ray width (0.84), the higher the moisture content of the wood.

Agroforestry systems are a more sustainable alternative to food and energy production without compromising existing agroecosystems. In this context, the study aimed to analyze the growth characteristics and the solar radition use efficiency of corn cultivated in different arrangements of agroforestry and monoculture systems. The study was conducted in the experimental area of the Laboratory of Agroclimatology of the Federal University of Santa Maria, Campus of Frederico Westphalen – RS, Brazil. The experimental design was a complete randomized block, arranged in a factorial scheme of 3 × 2 × 2 representing two arrangements of agroforestry systems (Intercrop I and Intercrop II) and the monoculture of corn; two forest species, Peltophorum dubium (Spr.) Taubert, denoted as P. dubium and the hybrid Eucalyptus urophylla S.T. Blake × Eucalyptus grandis Hill ex Maiden, denoted as Eucalyptus; and two crop years (Crop I and Crop II), with four replicates each. The growth rates varied between the different systems, with the highest values recorded for the absolute growth rate in the monoculture system, in both crop years, for the relative growth rate in the Eucalyptus-Intercrop I-Crop I and monoculture system-Crop II plots, and for the net assimilation rate in the Eucalyptus-Intercrop II in both crop years. The solar radiation use efficiency was varied between the different systems, with greater values of efficiency found in the Eucalyptus-Intercrop I-Crop I and in Eucalyptus-Intercrop II-Crop II plots. Therefore, different agroforestry arrangements influence corn growth; however, further studies related to this subject are needed as it is a way to optimize land use.

Agriculture has caused numerous concerns regarding the preservation of natural resources. In this context, agroforestry systems are emerging as a more sustainable alternative. The present study aimed to evaluate growth characteristics, radiation use efficiency, biomass partition, and yield of soybean grown in two agroforestry systems and full sun. A field experiment was conducted in Southern Brazil during the 2014/2015 crop year, in which transmissivity of solar radiation, leaf area index, radiation use efficiency, and yield of soybean were evaluated. The solar radiation dynamics varied among the study factors, mainly due to the agroforestry arrangements. Shading influenced the leaf area index, radiation use efficiency, biomass partition, and soybean yield. Based on the soybean yield values generated in this study, the use of more spaced agroforestry arrangements and Peltophorum dubium forest species is recommended. However, because the yield values were below the expected levels, it is not yet possible to confirm the full potential of soybean crop in agroforestry systems. Thus, new studies should be conducted in order to generate alternatives that make soybean cultivation feasible in agroforestry systems, such as assessing the use of more spaced agroforestry arrangements, the insertion of the soybean crop in the initial years of cultivation of agroforestry, as well as reduce intraspecific competition by decreasing the plant population of the crop.

O conhecimento do comportamento dos elementos meteorológicos de uma região é de grande importância para a tomada de decisões, principalmente no cultivo agrícola, pois influenciarão diretamente no crescimento e desenvolvimento das lavouras. Portanto, o objetivo deste trabalho foi conhecer a distribuição dos elementos meteorológicos pela distribuição não paramétrica de Kernel e analisar sua influência no cultivo de culturas. O estudo foi realizado com dados obtidos da Estação Meteorológica Automática A854-Frederico Westphalen. A estação está localizada no município de Frederico Westphalen, Rio Grande do Sul, Brasil. Os elementos meteorológicos utilizados no estudo foram a radiação solar global incidente, precipitação e temperatura média do ar. Os dados foram organizados em geral, por ano e por mês. Foi utilizado o método não paramétrico de estimativa da densidade do kernel. A aplicação do método não paramétrico de estimativa de densidade Kernel aos elementos meteorológicos permitiu observar a distribuição ao longo dos 10 anos de registo globalmente, no ano e no mês. Além disso, a distribuição possibilitou identificar os picos mais altos que estão relacionados a densidades mais altas. A observação de 10 anos de registros de dados de radiação solar, precipitação e temperatura do ar da estação meteorológica pelo método não paramétrico de distribuição de Kernel dá uma indicação de como os elementos estão se apresentando no período. Apesar de restrições específicas, o clima/tempo é adequado para o cultivo de espécies que vêm sendo utilizadas na região, seguindo seu zoneamento.