Effect of Chlorocholine Chloride and Triazoles – Tebuconazole and Flusilazole on Winter Oilseed Rape (Brassica Napus Var. Oleifera L.) in Response to the Application Term and Sowing Density

Winter oilseed rape is strongly responsive to changes in the plant density. Any change in plant density significantly affects the morphological characteristics and yield of the crop. In addition, plant growth habit can be modified by the use of plant growth regulators. Apart from plant growth regulators like eg. chlorocholine chloride some triazoles have dual properties (fungicide and plant growth regulator) eg. tebuconazole. The trials were carried out in the years 2006-2008 at the Institute of Plant Protection - National Research Institute in Poznan (Poland). The treatments consisted of chlorocholine chloride, tebuconazole and flusilazole applied in spring at the growth stage BBCH 30 and BBCH 50 of winter oilseed rape. The field trials were conducted with two sowing densities of winter oilseed rape: 60 seeds/ m2 and 120 seeds/m2. The vegetation seasons varied according to the weather conditions, and the second testing year was characterised by drought in May and June. In the experiments plant height, SPAD units, number of siliques per plant, seed number per silique, weight of thousand seeds, yield, protein and fat content in the seeds were estimated. The increase of silique numbers per plant appeared only at the lower sowing density as a result of the application of tebuconazole or a mixture of tebuconazole with CCC. Flusilazole had a positive impact on seed number per silique. At both sowing densities, changes in the weight of a thousand seeds under the influence of the test preparations, were observed only in that year which had wet weather conditions. A more favourable effect of the test substances on the weight of a thousand seeds was obtained at the lower sowing density. All the tested substances positively affected SPAD unit values at the lower sowing density. At the higher sowing density, SPAD unit values increased after the application of flusilazole, and after a mixture of CCC + tebuconazole. The tested substances had a positive impact on plant yield but they did not affect the protein and fat content in oilseed rape seeds.