Sunflower is an important crop for Integrated Crop-livestock Systems (ILCS), and one of the main management difficulties identified in this crop is weed control, especially under no-till conditions when chemical weed control is not allowed. Therefore, the aim of this research was to evaluate the effect of greater sunflower population density on weed control, and its impact on sunflower yield, in an ILCS with eucalyptus in an Environmental Protection Area. Two population densities were tested (45 and 90 thousand pl. ha-1) in two crop systems (sunflower monoculture and sunflower-eucalyptus integration). An additional treatment was provided in the sunflower-eucalyptus integration, and 5 positions (2,4; 4,8; 7,2; 9,6; and 12 m) between the tree rows were evaluated. In a randomized block design, with eight repetitions, weed density and weed dry matter were determined at 40, 70 and 100 days after crop emergence. Also, phytosociological indices were calculated. The following yield components were evaluated: head diameter, number of achenes per head, and 1000-achene weight. There was lower weed infestation on the high density treatment in both systems. There was no difference of weed occurrence in the 5 positions between the tree rows. Sunflower yield was higher in the greatest population density in both systems. Increasing population density in sunflower crop is a practicable management to control weeds and to gain higher yield under free-herbicide conditions.

A Revista Ciência Agronômica é voltada para estudos relacionados com as Ciências Rurais e Recursos Naturais

We proposed and evaluated a new approach (“Farm-school project”) to develop children's awareness about the role of people in agricultural production and environmental quality. The materialization of the “Farm-school” project was performed by a theoretical-practical 4-hour visit at an experimental farm. 240 Elementary school students were evaluated through concept maps and drawings, before and after the visit. There was a conceptual evolution in concept maps of 41 and 82%, and an increased number of categories per drawing of 23% and 37%. In concept maps, students did not relate people to the different spheres of agricultural production before the farm visit, but after, people became the main element. After the visit, students began to portray not only productive aspects in their drawings but also processes involving production, such as soil conservation practices and maintenance of mulch for soil cover. With the population concentrated in urban areas, there is a lack of contact with the rural landscape, generating a distorted view of food systems and rural land use, which affects social drivers and pro-environmental behavior. This imposes an educational task on governments to bring about information on agricultural production to elementary school students. We have proven the effectiveness of the “Farm-School” project as a low-cost educational policy alternative and a tool to increase children’s awareness about the role of people in agricultural production and environmental quality since students come to a better understanding of where food comes from and how it is produced.