Manejo cultural e mecânico de plantas infestantes na produção orgânica de mandioca (Manihot esculenta)

Abstract

The crop of cassava (Manihot esculenta) is very important for family farmers, who cultivate for self-consumption and commercialization. The productivity of this crop can be limited by the interference of weed plants, which limit their development, competing for water, light and nutrients. The management of these species can be carried out with soil cover, followed by notillage, keeping the straw over the soil. The use of weeding is another way of controlling weed plants in the cassava culture, but it has a high cost, besides being able to damage the branches and roots of the culture. This work evaluated the use of integrated managements in the control of weed plants, namely, the use of different cover crops, integrating different weeding intensities. The experiment was conducted in the field, in the Experimental Area of the Federal University of Fronteira Sul, Chapecó Campus. The design used was at random blocks with a subdivided plot. The treatments were arranged in a 4Х3 factorial scheme, the first factor being types of cover: no cover, black oats, radishes, vetch + rye; and the second factor allocated was weeding intensities (45 days after emergence - DAE) and two weeds (30 and 60 DAE). The physiological variables evaluated were photosynthetic rate (A), internal CO2 concentration (Ci), transpiration rate (), carboxylation efficiency (EC) and efficient water use (UEA). Total productivity, number of commercial and non-commercial roots, average length and average root diameter, number of roots per plant and branch diameter were also evaluated. There was no interaction between the factors studied, and the analyzed variables were more responsive to weeding, with little effect from cover species. Variables such as average diameter, average length, productivity and number of commercial roots showed the greatest response to the increase in the number of weeding. In the physiological variables, it was possible to observe improvement in the results with just one weeding. The infesting plants were shown to have a great capacity to cause losses in the cassava productivity, in which weeding proved to be an efficiency control measure for its management.