The areas of maize production harbor a high number of insect species, some of which are considered pests that cause damage to the crop. The methods of pest control have been a cause of concern for the society since the use of chemicals and the environmental problems arising from this practice indicate the need to search for alternatives to control. In this sense, it is necessary to seek an agricultural production system that contemplates environmental sustainability and promotes biodiversity in the Agrosystem, among which the use of biological agents is highlighted. The objective of this research was to update through a bibliographic review the advances in the literature on biological control of maize crop pests. For the development of this article, we used the method of approach the analytical and as procedural method the monographic, through bibliographic research, using specialized doctrines, appropriate to the object of the study and legislations. Because of the observed aspects, it is possible to conclude that the group of natural enemies that act as biological control agents is formed by parasitoids, predators and entomopathogenic microorganisms. The rationalization of the use of chemicals should be associated with the use of biodefensives in integrated pest management. Advances in the legislation of biological products in Brazil are fundamental to give speed to the registration of new alternatives of biological control, aimed at the safety of the environment, human health and that are generated without the exploratory use of biodiversity.
The leaf area index (AFI) is an important variable when evaluating the growth, development and possible productivity of a crop. The objective of this article was to determine mathematical models that allow estimating the leaf area of tobacco from measurements of dimensions of length and width of tobacco leaves. The experimental design used was in blocks with four replications and two planting times. The treatments consisted of five commercial cultivars of Virginia type tobacco and Burley type. Of which the leaves were detached from the stem, and these leaves were fractionated in limbo and petiole. Its leaves were 10 models were obtained to estimate the leaf area of tobacco. All the models presented a significant test to estimate the leaf area. The power and quadratic models presented values of determination coefficients higher than linear models. It had the best results with the nonlinear power and quadratic model, using the squared width multiplied by length. Therefore, the measurements of the leaf area of tobacco can be estimated from potential, linear and quadratic equations with good precision. The models that use linear squared width measurements multiplied by leaf limbo length satisfactorily estimate the leaf area of tobacco.
Aims: Tobacco cultivation is important in the income composition of family farmers. The use of soil cover plants is a practice that plays an important role in keeping the soil covered and reducing the effects of water erosion and improving the physical, chemical and biological conditions of the soil. The objective of this study was to evaluate the benefits of using different species for soil covering preceding the production of tobacco in the no-tillage system. Place and Duration of Study: Two experiments were conducted in Jaguari-RS, in the years 2015 and 2016. Methodology: The treatments were different species of soil cover crops, preceding the cultivation of tobacco (nicotine tabacum) as described: Black oat (Avena strigosa); Common Vetch (Vicia sativa L.); Consortium of Black Oat + vetch and white lupine (Albus L.). For both experiments, the experimental units consisted of plots of 3.5 x 3 m, comprising an area of 10.5 m2. The plant growth, production of the dry mass and decomposition of crop residues, of the cover crops, as well as weed infestation and tobacco yield were evaluated. Results: Among the winter cover crops, black oats and white lupine stood out, as they showed fast growth and higher dry mass production, resulting in higher tobacco yield. These cover crops showed the most promising, combining the benefits to soil conservation and the sustainability of the production system. Conclusion: In this study it was observed that the treatments with cover crops that presented the highest dry mass production were the same ones that provided the highest tobacco yield, making it possible to affirm that there is a positive relation between the production of the dry mass of precedent crop with tobacco yield.
O presente trabalho teve por objetivo analisar o comportamento fenológico de cultivares de soja em diferentes épocas de semeadura em terras baixas, determinando a altura das plantas, duração do ciclo e dos subperíodos de desenvolvimento. O experimento foi realizado na área experimental do Instituto Federal Farroupilha - Campus São Vicente do Sul, sendo composto por seis cultivares de soja. O delineamento experimental ocorreu em blocos ao acaso, com quatro repetições. Foram realizadas três épocas de semeadura (19/10, 29/11 e 29/12/2018). A parcela foi composta por seis linhas com 5 metros de comprimento e espaçamento de 0,45 m entre fileiras, na densidade de 30 plantas/m². Para o acompanhamento fenológico foram demarcadas duas plantas por parcela, e avaliadas duas vezes por semana seu estágio fenológico. A altura das plantas foi determinada após as plantas atingirem a maturação fisiológica. Realizou-se a análise de variância para verificar se havia diferença entre as variáveis analisadas, sendo aplicado o teste de Tukey (P<0,05) para comparação de médias. A análise de variância mostrou que houve interação dos fatores época de semeadura e cultivar para todas as variáveis. Portanto, diferentes épocas de semeaduras influenciam na altura das plantas, duração do ciclo e dos subperíodos de desenvolvimento da cultura. Palavras Chaves: Fenologia; Épocas de semeadura; Terras baixas.
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