Determination of critical period of weed competition with the cultivation of maize (Zea mays L.)

Abstract

The determination of the critical period of competition between the weeds and the economic cultivation is the only efficient road to only establish methods of weeds handling during the time that the cultivation requires it and this way to facilitate the coexistence interespecific economic weeds-cultivation. To achieve that objective, it was carried out an investigation during two years (2007-2008) in the National Institute of Agriculture Science, where it was evaluated at random by means of a design of blocks, with treatments at the 16, 24, 32, 40, 48 and 54 days after the germination with and without weeds, and two witness, with and without handling during the whole cycle of the corn. The dominant weeds in the system, was Cyperus rotundus and Rottboellia exaltata attributable to the chemical methods of handling precedents. In accordance with the carried out statistical analyses the critical period of competition of the weeds with the cultivation of the corn was in the period that lapses from 24 to 40 days after having germinated the cultivation, period during which the works of handling of the weeds cannot miss the cultivation, preferably in a mechanical way, to guarantee high yields and ecological balance in the productive system. Corn yields were higher when the crop was treated at the critical period reaching values between 11 and 12 t.ha-1 .Work before and after this alone period they contribute to elevate the energy expenses and to unbalance the agroecosystem.