Determinação do período crítico de competição entre as ervas infestantes e o feijão vulgar - Phaseoulus vulgaris L. para o uso de vagem verde

Abstract

Common bean (Phaseolus vulgaris L.), an agricultural product of high economic and social expression, is one of the population's staple foods, thus constituting the main source of protein supply for the lower income classes of the rural and urban population (Mushi, 1985 ). Despite its importance, common bean yield is considered low due to abiotic and biotic factors, with weeds being one of the most important factors contributing to its low productivity in Africa if its control is inadequate (Afors, 1994). The control of weeds is a very important production factor for any crop, because when they compete with crops in the use of water, nutrients, light, CO2 and space, they cause huge production losses. On the other hand, the intensity of this competition depends on several factors, among which species, weed infestation density, soil moisture, height and crop growth habit stand out (Ranson, 1989). There is a stage in the development of the cultivated species when it is more sensitive to competition from invasive flora - this is called the critical period of competition. It can be defined as the minimum period during which the crop must be free of weeds, in order to avoid losses in production (Matos et al, 1991). The control of weeds in cultivated areas has been carried out using mechanical, physical, chemical, biological and preventive methods. These practices have shown to be ineffective in the medium term, leading the producer to systematically repeat the process, which in addition to raising the maintenance cost, brings, in some cases, environmental implications such as environmental pollution (Whittaker and Fenni, 1971; Einhllig; , 1986; Rice, 1974). In many tropical regions, especially in small-scale agriculture (family sector), many farmers do not have information regarding the most opportune time to eliminate weeds in the bean crop (FAO, 1990). Herbs, when not controlled in the bean crop, can cause production losses in the order of 50% (Segeren et al, 1994). Hence, the elimination of weeds in this culture is an extremely important and indispensable practice, as it helps to minimize the drop in production and productivity (Fleck, 1991). Thus, the objectives of this study are: -Determine the critical period of competition between weeds and the green bean crop, -Determine the most opportune time to remove the weeds, -Determine production losses caused by weeds in the green bean crop