Effect of nitrogen rate and application time to yield and quality of winter oilseed rape (Brassica napus L. var. oleifera subvar. biennis)

Oilseed rape is one of the most important sources of vegetable oil in the world. Nitrogen is one of important components of oilseed rape and has strong effect on seed yield and quality. The objective of the study was to evaluate the influence of nitrogen rate and application time to yield and quality of winter oilseed rape. Field trials were carried out at the Jogeva Plant Breeding Institute in 2007/2008 and 2008/2009. Ammonium nitrate (nitrogen content 34.4%) was used as top-fertilizer. Three different nitrogen rates: 120, 140 and 160 kg ha-1 (in active ingredient) and three different application timings were used: A) once at the beginning of spring vegetation, B) A + when the main stem was 10 cm, C) B + start of flowering in equal portions. By the results can be concluded that the amount of fertilizer had not as strong impact to seed yield and quality as fertilizer application time. The highest yields of seed and raw oil were obtained from the variant of split-N treatment (40+40+40) of 120 kg ha-1.