RESUMEN
RESUMEN El maíz es el segundo cereal de mayor producción en Colombia con un 21,9 % de la superficie total. La plaga Spodoptera frugiperda ataca la planta desde las primeras semanas de crecimiento, devorando sus hojas, tallo y granos; disminuyendo el rendimiento de los cultivos. Esta plaga se controla con el uso indiscriminado de plaguicidas sintéticos como: carbofurano, clorpirifos y atrazina. En esta investigación, los extractos de Azadirachta indica, Piper nigrum, Petiveria alliacea y sus mezclas; y los extractos de Nicotiana tabacum, Lippia alba, Allium sativum y sus mezclas se aplicaron como bioplaguicidas en plantas de maíz amarillo tradicional. Después de la tercera semana de crecimiento, los tratamientos se aplicaron dos veces al día cada tres días durante siete semanas. Las variables estudiadas fueron número de larvas muertas, altura de las plantas y daño en hojas y tallos. Las plantas tratadas crecieron dos veces más y su grado de afectación, según la escala de Mihm, fue menor que las plantas del grupo testigo. Los porcentajes de eficacia de las seis especies vegetales y sus mezclas fueron representativos (>80 %), de acuerdo con Henderson y Tilton, demostrando que estos extractos vegetales son una alternativa viable para el control de S. frugiperda.
ABSTRACT The corn crop is the second largest cereal in Colombia with 21.9 % of the total area produced. The plague Spodoptera frugiperda, attacks the plant from the first weeks of growth, devouring its leaves, stalk and grains; decreasing crop yield. This pest is controlled by the non-controlled use of synthetic pesticides such as, carbofuran, chlorpyrifos and atrazine. In this research, the extracts of Azadirachta indica, Piper nigrum, Petiveria alliacea and their mixtures; and extracts of Nicotiana tabacum, Lippia alba, Allium sativum and their mixtures, were applied as bioplaguicides in corn plants. The application was performed twice a day each two days for seven weeks, after of third week of growth (when the larvae were first observed). The number of dead larvae, plant height and damage in leaves and stems were the study variables. The treated plants grew twice and their degree of affection, according to the Mihm scale, was lesser than plants in the control group. The efficiency percentages of the six plant species and its mixture were representative (>80 %), in according to Henderson and Tilton, resulting in these plant extracts are a viable alternative for pest control of S. frugiperda.
RESUMEN
La Agroecología es un referente teórico, que sirve de orientación general para las experiencias de agriculturas ecológicas, desde el ámbito local, para el fortalecimiento de los sistemas de producción, con un respeto por las estructuras ecológicas y sociales. Desde este fundamento, se generó la necesidad de ganar espacios en la academia y las instituciones de investigación, para enriquecer las bases epistemológicas de la Agroecología a través de la investigación científica, buscando hacer un cambio del paradigma científico. Se plantea la Agroecología como un movimiento social, sin desconocer que los resultados cimientan los soportes para las investigaciones científicas de la academia. Entonces, la interacción entre la investigación en Agroecología y los movimientos agroecológicos son un desafío para ésta, que hasta ahora no ha planteado estudios sin que haga una división entre el modelo reduccionista del paradigma científico convencional, y los enfoques sistémicos y holísticos de la Agroecología, buscando considerar estudios integrados que circulen en la complejidad de los sistemas naturales y sociales. Para entender los enfoques de la Agroecología y el planteamiento de la investigación, se hace necesario conocer las bases conceptuales. Así la Agroecología como planteamiento investigativo tiene la premisa de tener una formulación social, que se sustente en movimientos participativos para la construcción de conocimientos a partir de experiencias ancestrales o principios de coevolución social y ecológica.
Agroecology is a theoretical referent that serves as general orientation for the ecological agricultural experiences from the local sphere for the strengthening of production systems with all due respect for the ecological and social structures. From this foundation, the need to gain spaces in academic fields and research institutions has generated, in order to enrich the epistemological bases of Agroecology by means of scientific investigation, searching for a change in the scientific paradigm. Agroecology is considered a social movement without ignoring that the results consolidate the support for academic scientific research. Consequently, the interaction between research in Agroecology and the agro-ecological movements are its challenge that, so far, has not expressed the need for studies without making a division between the reductionist methods of the conventional scientific paradigm and the systemic and holistic approaches to Agroecology, searching for consideration of integrated studies circulating in the complexity of natural and social systems. In order to understand the Agroecology approaches and the research formulation, it is necessary to know the conceptual bases. Thus, Agroecology as a research approach has as a premise to have a social formulation supported in participation movements for the construction of knowledge from ancestral experiences or social and ecological co-evolution principles.
Asunto(s)
Humanos , Agricultura Sostenible , Investigación , Ecología , Pueblos IndígenasRESUMEN
Quebra-pedra (Phyllanthus stipulatus (Raf.) Webster, Euphorbiaceae) is a popular remedy used to reduce uric acid in blood and to facilite the elimination of kidney stones. The research was carried out at the Vegetable Crops Experiment Station of the National Institute for Amazonian Research, in Manaus, Amazonas, Brazil, using seeds of a local wild population. A split-plot design was used, where the main plots were the natural environment and 50% shade, the subplots were constituted by doses of 0,2,4,6, 8 and 10 kg of organic compost (OC)/m2 and contained 20 plants in 1 m2. The following characters of the 6 useful plants per subplot were evaluated: stalk diameter at soil level, plant height, root, stalk, branch and leaf biomass (fresh and dry). No significant differences among environments were found for total plant biomass (63.1 g vs 62.3 g fresh wt, 26.6 g vs 25.6 g dry wt, respectively), but were found for height (70.0 cm in sun light vs 96.2 cm in shade) and, consequendy, for stalk biomass (5.1 and 5.7 g dry wt, respectively). Quebra-pedra responds to organic manure, both in total biomass and in all of its components, with an increment of 43% in total biomass between the minimum and maximum treatment, but the benefit/cost ratio suggests that 4 kg of OC/m2 is the maximum amount that is economically viable in the soil used. Total biomass is composed of 17.2% root, 22.3% stalk, 23.1% branches and 37.4% leaves. Plant growth demands considerable potassium but little phosphorous, magnesium or micronutrients.
O quebra-pedra (Phyllanthus stipulatus (Raf.) Webster, Euphorbiaceae) é um importante remédio popular usado para reduzir o ácido urico no sangue e facilitar a eliminação de cálculos renais. Para avaliar a produção de biomassa dessa espécie utilizou-se sementes de populações naturais num experimento realizado em Manaus, AM. Adotou-se um delineamento experimental de parcelas subdivididas, onde as parcelas foram: (a) o ambiente natural e (b) o ambiente com tela plástica sombrite com 50% de luminosidade, e as subparcelas constituídas por dosagens de 0,2,4,6,8 e 10 kg de composto orgânico/ m2. Não foram encontradas diferenças significativas entre os ambientes na biomassa total das plantas (63,1 g vs 62,3 g fresca e 26,6 g vs 25,6 g seca), embora tivessem sido encontradas para a altura (70,0 cm a pleno sol vs 96,2 cm sombra) e, conseqüentemente, para a biomassa do caule (5,lg vs 5,7 g seca, respectivemente). O quebra-pedra responde bem a adubação orgânica, tanto na biomassa total, como em todas as partes da planta. A melhor resposta, em termos de rendimento, se deu sob o efeito de 10 kg de CO/m2 incorporado ao solo ( 1,26 kg/m2 de biomassa fresca e 0,55 kg/m2 de biomassa seca). Em comparação com a testemunha, este tratamento produziu 43% mais biomassa seca total. No entanto, a razão benefício/ custo sugere que 4 kg de CO/m2 é a quantidade máxima que é economicamente viável no solo usado. A biomassa total é composta de 17,2% de raízes, 22,3% de caules, 23,1% de galhos e 37,4% de folhas. O crescimento das plantas exige muito potássio e pouco fósforo, magnésio e micronutrientes.