Effectiveness selectivity and persistence of some herbicidal mixtures applied at cereal crops growth
2008
Stoimenova, I. | Mikova, A. | Stratieva, S. | Aleksieva, S.
The aim of this study is determination of the effectiveness selectivity and persistence of some herbicidal mixtures applied at wheat and rye growth. The investigation was performed as two factor field experiment in four replications with plot size of 120 m2 and includes different rates of nitrogen and phosphorus fertilization. The herbicidal effect of chlorsulphon in dose of 1 g/da and izoproturon - 300 g/da was manifested until the phase of stem extension of wheat mainly with regard to the density of infestation. In the stage beginning of milky ripeness the herbicidal effect on the density of infestation decreased remarkably at the non fertilized variants and approximated to the variants with higher fertilization rates without herbicides. Rye has a high competitiveness regard to the quantitative infestation by annual weeds which was a reason for application of herbicidal mixture in the investigated doses. Rye is more sensitive to the herbicidal mixture 1.4 g/da glin and 350 g/da tolurex at fertilization rates N8P4 in comparison to the mixture glin 1 g/da and tulorex 450 ml/da. The lowest yield of wheat was obtained from unfertilized and untreated variants. In the variants with chemical weed control without fertilization the yield increased with 175%. Considerable higher yield was obtained from the variants with higher fertilization rates. At the variants without chemical weed control the lower fertilization rates increased the yield. The highest yield from rye was registered in the variants with fertilization doses P4N8 kg/da. The lowest yield was observed in the variants without nitrogen fertilization. The residual quantities of the herbicides chloroxuron and izoproturon in the soil layer 0-20 cm and in the wheat corn were under the accuracy of the methods for their determination / 0.01 mg/kg/ and they were not of great risk for contamination of the environment.
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