Periods of weed plant interference in canola
Daiani Brandler1*, Leandro Galon1, Altemir José Mossi1, Thalita Pedrozo Pilla1, Rodrigo José Tonin1, Cesar Tiago Forte2, Felipe Bianchessi1, Emanuel Rodrigo de Oliveira Rossetto1 and Siumar Pedro Tironi3
1Federal University of Fronteira Sul, Erechim, RS, Brazil.
2Federal University of Santa Maria, Santa Maria, RS, Brazil.
3Federal University of Fronteira Sul, Chapecó, SC, Brazil.
The objective of this work was to determine the periods of interference of turnip, ryegrass and black oats infesting the canola crop. Two models of interference were studied: first, the canola cohabited with weeds for increasing periods up until 0, 7, 14, 21, 28, 35 and 42 days after the emergency (DAE) and throughout the cycle; second, the culture was kept free of the infestation for the same periods described previously. At 51 DAE, the variables related to canola and weed morphophysiology were determined. In the harvest of the crop, was measured the number of siliques, a thousand grain mass and grain yield. The physiological variables, photosynthetic rate, internal CO2 concentration, perspiration rate, stomach conductance of water vapors, carboxylation efficiency and efficient water use did not show significant variation. The dry mass was reduced by 79.21% when canola culture was always in competition with ryegrass, turnip and black oat weeds. The number of siliques and the mass of one thousand grains also decreased as the period of competition with the turnip, ryegrass and black oat weeds increased. The period before the interference (PAI) of the weeds ryegrass, turnip and black oats goes up to 25 DAE of canola. The critical interference prevention period (PCPI) for canola culture goes from 25 to 60 DAE. And the total interference prevention period (PTPI) is 60 DAE. Interference from weeds has reduced by 94.05% the productivity of canola grains when it has not received control of ryegrass, turnip and black oats.
Weeds have to be controlled from 25 to 60 days after emergence to prevent canola yield reduction by up to 94%.