Sugarcane (Sacharum officinarum L.) monocropping has had a great socio-economic and environmental impact in Brazil, and agroforestry systems have been considered as an alternative for more sustainable production; however, there is a lack of field research under such conditions. The aim of this study was to evaluate the growth rates, radiation use efficiency and yield traits in sugarcane cultivated in the understory of Aleurites fordii, in two agroforestry arrangements and monocropping systems. A field experiment was conducted from July 2015 to June 2016 in the city of Frederico Westphalen, Rio Grande do Sul, Brazil. The radiation use efficiency, assimilate partitioning, leaf area index, absolute growth rate, net assimilation rate, number of tillers, plant height, % of intercepted solar radiation, extinction coefficient, and yield in each system was evaluated. In agroforestry systems, the dynamic interactions between multiple plant species change with the time and can result in unique microclimates. The use of agroforestry systems in 12 x 12m arrangements should be prioritized because it enables greater yields and radiation availability in the understory. This study sought to provide new sustainable alternatives for farmers in order to increase the diversification of the rural property and maintain the preservation of existing agroecosystems.An Acad Bras Cienc (2018) 90 (4) 3266FELIPE SCHWERZ et al.

Soybean (Glycine max L.) monocropping have had a great socioeconomic and environmental impact on the world and agroforestry systems has been considered an alternative for more sustainable production. The aim of this study was to evaluate the effect of different arrangements of agroforestry systems of the species E. urophylla x E. grandis and P. dubium and the pruning of the trees on the dynamics of solar radiation and soybean yield. A field experiment was conducted in Southern Brazil. In order to achieve the objective of the study, the solar radiation transmissivity and the productive performance of the soybean were evaluated. In this study, the soybean yield was determined by the arrangement of the agroforestry system and forest species utilized. The soybean crop cultivated in the understory of the P. dubium trees showed the highest yield response. The use of silvicultural practices for the management of forest species should be considered to generate the balance of the productive system. In this context, tree pruning is a viable side for agroforestry systems, as it promotes an increase in the incidence of solar radiation in the understory, resulting in an increase in soybean yield, especially when integrated with P. dubium.

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

Effect of season and irrigation on the chemical composition of Aloysia triphylla essential oil Aloysia triphylla is an aromatic plant used in several industrial sectors, owing to the chemical properties of its essential oil. Biosynthesis of organic compounds is influenced by the growth conditions. As such, temporal and spatial variation affect the chemical composition of essential oils. We hypothesized that: i) the chemical composition of A. triphylla essential oil is influenced by differences in irrigation and season; and ii) the major components of A. triphylla essential oil do not vary between treatment conditions. To test these hypotheses, we determined the chemical composition of A. triphylla essential oil as a function of four seasons crossed with four irrigation levels. A completely randomized experimental design with a randomized block in a 4 × 4 factorial scheme, representing the four seasons of the year (summer, autumn, winter, and spring) and four irrigation levels (50%, 75%, 100%, and 125% of the reference evapotranspiration), was used with four replicates. Our results show that the chemical composition of A. triphylla essential oil varied with the two study factors, of which season was the major factor. The highest concentrations of constituents classified as monoterpene and sesquiterpene were observed in the summer season, and the highest constituents of the other group of compounds were observed in winter. In addition, the major components of the essential oil were α-citral, limonene, and β-citral, and their levels were the highest during winter.

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.

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One of the greatest challenges in crop science worldwide is to generate a balance between crop production and environmental preservation. Agroforestry systems present promising strategies for balancing environmental health and crop production. The aim of this study was to evaluate yield components and the juice quality of five sugarcane crop years cultivated in the understory of Aleurites fordii, in two intercropping systems and a monocropping system. A field experiment was conducted from November 2011 to June 2016 in the city of Frederico Westphalen—Rio Grande do Sul, Brazil. Information generated in this study confirms the viability of the cultivation of sugarcane in agroforestry systems, and provides information for farmers which can be used to assist in the planning of more ideal agroforestry arrangements. Agroforestry systems should consider the benefits of both forest and cultivated plant species. In this study, A. fordii trees had greater growth in the intercrop II system; however, this system promoted reductions in sugarcane yield components due to the lowest relative amount of solar radiation intercepted by sugarcane plants. For sugarcane production, the use of an intercropping system with 12 × 12 m2 arrangements should be prioritized, because it promotes greater sugarcane yields when compared with 6 × 6 m2 intercropping systems; however, significant differences were not observed when the system (12 × 12 m2) was compared with the monocropping system for most of the analyzed variables. This study sought to provide new sustainable alternatives for farmers in order to increase the diversification of rural properties and maintain the preservation of existing agroecosystems.

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.