The objective of the study was to evaluate the growth and production efficiency of forage-grain dual-purpose wheat in two arrangements and four agroforestry systems (Intercrop-I and Intercrop-II), as well as to evaluate crop management for the wheat crops in two planting seasons (Crop Season I-2014 and Crop Season II-2015. The experiment was conducted in a randomized complete block design, factorial scheme 7x2x2, with seven cultivation systems eucalyptus urophylla x eucalyptus grandis Intercrop

Agroforestry systems have been highlighted in the agricultural environment as an alternative form of sustainable production to meet the growing demand for food and energy with less environmental impact. Thus, the aim of this study was to evaluate the effect of different forest species on the dynamics of solar radiation and the productive response of soybean grown in agroforestry systems. Two field experiments were carried out in the city of Frederico Westphalen - Rio Grande do Sul, Brazil. In order to reach the aim of this study, the solar radiation transmissivity and the productive performance of soybean were evaluated. Productivity followed the same tendency as solar radiation transmissivity; in an agricultural year, the species with the higher incidence of solar radiation to the understory presented the best yield. The forest species Schizolobium parayba, Peltophorum dubium and Parapiptadenia rigida were used as they present the potential to compose the agroforestry systems; their canopy structure and leaf architecture provide greater availability of solar radiation in the subforest. The interception of solar radiation by the forest component of more than 50% significantly reduces soybean yield in agroforestry systems, requiring silvicultural practices that promote the availability of solar radiation in the understory.

Soybean (Glycine max) stands out in the agricultural scene, being one of the main sources of protein and oil for human and animal nutrition. The aim of this study was to evaluate the growth, radiation use efficiency, and the yield of soybean, cultivated under four levels of artificial shading to simulate the environment provided by an agroforestry system. A field experiment was conducted in Frederico Westphalen, Rio Grande do Sul, Brazil, from December 2015 to April 2016. The experimental design was completely randomized with four levels of shading (0, 30, 50, and 70%) as treatment, and eight collections of plants at specific growth stages. The growth and yield traits of the soybean crop are influenced differently as a function of shade levels. Thus, the simulation of an agroforestry system from artificial shading allowed the recommendation of soybean cultivation for intercropping systems, provided that the interception of solar radiation by the tree component is less than 30%, in order to enable soybean cultivation. Efeito do sombreamento artificial no crescimento e produtividade da sojaRESUMO: A soja (Glycine max) destaca-se no cenário agrícola mundial, sendo uma das principais fontes de proteína e óleo para nutrição humana e animal. O objetivo deste estudo foi avaliar o crescimento, a eficiência do uso da radiação e a produtividade da soja cultivada sob quatro níveis de sombreamento artificial visando similar o ambiente proporcionado por um Sistema agroflorestal. Um experiment de campo foi conduzido em Frederico Westphalen, Rio Grande do Sul, de dezembro de 2015 a abril de 2016. O delineamento experimental empregado foi o inteiramente casualizado com quatro níveis de sombreamento (0, 30, 50 e 70%) como tratamento, e oito coletas de plantas em estádios específicos de crescimento. As características de crescimento e produtivas da cultura da soja são influenciadas diferentemente em função dos níveis de sombreamento. Assim, a simulação de um Sistema agroflorestal a partir de sombreamento artificial permitiu a recomendação do cultivo da soja para sistemas consorciados, desde que a interceptação da radiação solar pelo componente arbóreo seja inferior a 30%, a fim de viabilizar o cultivo da soja. Palavras-chave: sistemas agroflorestais; Glycine max; análise de crescimento; variáveis meteorológicas; radiação solarEffect of artificial shading on soybean growth and yield Rev. Bras.

& Key message The use of reduced planting spacings is an important strategy to increase the carbon storage in the abovebelowground biomass and should be recommended for future exploitation of forest energy plantations when the purpose intended is the production of biomass for energy. & Context Recent concerns about global warming have resulted in more concerted studies on quantifying carbon storage in forest systems. Forest energy plantations play an essential role in the carbon storage. & Aims We proposed to evaluate the carbon storage and partitioning in short-rotation forest plantations and to characterize the elemental composition and energetic properties of the forest species Eucalyptus grandis W. Hill ex Maiden, Mimosa scabrella Benth, and Ateleia glazioviana Baill, grown under four planting spacings in Southern Brazil. & Methods A field study was conducted in order to evaluate forest carbon stock and wood composition using samples collected by direct method. The four spacings evaluated were 2.0 × 1.0, 2.0 × 1.5, 3.0 × 1.0, and 3.0 × 1.5 m. & Results The Eucalyptus grandis stored 327.1 Mg C ha −1 at 2.0 × 1.5-m spacing. When compared with the 3.0 × 1.5-m spacing, we observed a reduction of 29% in carbon stored. All forest species showed higher carbon storage in the following partitioning pattern: trunk>roots>branches>leaves>litter. Forest species energetic properties and elemental composition were not affected by planting spacing. On the other hand, variations according the tree portions were observed. For the carbon stocks in the soil, we observed an average accumulated carbon stock for the forest species studied of 77.4 Mg C ha −1 (0-40 cm). & Conclusion Forest managers can accelerate growth and increase the forest carbon storage and biomass yield by using reduced planting spacing that are smaller than the current pattern used by the majority of the forest producers, which is 3.0 × 1.5 m. For Eucalyptus grandis and Mimosa scabrella, the planting spacings recommended to produce biomass and improve carbon stocks were 2.0 × 1.5 and 2.0 × 1.0 m, respectively.

O objetivo desse estudo foi determinar a soma térmica necessária do plantio à emergência de toletes de cana-de-açúcar e o filocrono de mudas da emergência até a emissão da quarta folha de genótipos de cana-de-açúcar desenvolvidos para o cultivo na região Sul do Brasil. Um experimento em casa de vegetação, com 15 genótipos foi conduzido em Frederico Westphalen, RS. Os genótipos de cana-de-açúcar utilizados foram UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, RB855156, RB966928, RB946903, RB925345, RB965902, RB867515, RB925268, RB935744, RB845210, IAC87-3396. O delineamento experimental foi o de blocos ao acaso com 4 repetições. Calculou-se a soma térmica necessária do plantio a emergência e a soma térmica da emergência até a emissão da quarta folha e seu respectivo filocrono (°C folha-1). A soma térmica, bem como o filocrono, mostrou grande variação entre os genótipos. Os genótipos UFSM FW obtiveram os melhores desempenhos e a cultivar UFSM LUCI FW foi a com menores taxas de soma térmica e filocrono necessário para emissão de folhas, evidenciando crescimento e desenvolvimento superiores aos outros genótipos nas condições climáticas da região Sul do Brasil.

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.

This study determined the meteorological variable that most contribute to the productivity of sugarcane stalks in the northwest and central regions of Rio Grande do Sul. The following sugarcane genotypes were used: UFSM XIKA FW, UFSM LUCI FW, UFSM PRETA FW, UFSM DINA FW, UFSM MARI FW, and IAC87-3396. The UFSM cultivars originate from a mutation process in the breeding program conducted at the Federal University of Santa Maria, Frederico Westphalen campus, and have low temperature tolerance. The productivity-associated morphological characters included in the models were average stem diameter, average stem number per meter of furrow, and average stem height. The following meteorological variables were used: minimum air temperature, precipitation, incident solar radiation, and accumulated thermal sum. Pearson’s correlation, canonical correlations, and Stepwise regression were performed between morphological characters and meteorological variables: minimum air temperature had the greatest influence on sugarcane productivity in the studied regions, and accumulated thermal sum showed the highest correlation and contributed most to stem diameter and average stem height. Thus, the models indicated that the growth of sugarcane is positively associated with the accumulated thermal sum, and sugarcane can be cultivated at the studied regions.

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