Effects of nutrient supply and sowing time on the yield and pathological traits of winter oilseed rape

The fertilizer response of oilseed rape (Brassica napus var. oleifera f. biennis L.) was investigated on the chernozem soil in Eastern Hungary in a three-year experiment with two sowing times. The results proved that oilseed rape had high fertilizer (N+PK) demand. In the experiments, N = 210 kg ha−1 +PK proved to be the optimal fertilizer dose. The yield-increasing effect of fertilization was 800 to 1300 kg ha−1, depending on the year. The maximum yield (5000 kg ha−1) was obtained in the year with least infection. The excellent natural nutrient-providing ability of chernozem soil was confirmed by the high yield level (3000–4200 kg ha−1) of the control treatment (N = 0 kg ha−1 +PK). The results showed that the specific fertilizer utilization efficiency of oilseed rape decreased if the dose of N+PK fertilizer was increased (being 19–27 kg/1 kg NPK in the control treatment and 11–12 kg/1 kg NPK in the N = 210 kg ha−1 +PK treatment). On the other hand, fertilization improved the water utilization from 4–8 kg/1 mm precipitation + irrigation water to 11–14 kg/1 mm precipitation + irrigation water. The results of these studies confirmed that hybrid rape had excellent adaptability to the sowing time. The results of Pearson’s correlation analysis showed a strong correlation (0.6*–0.9**) between the spring precipitation and temperature and the most important diseases (Sclerotinia, Alternaria, Peronospora, Phoma) attacking oilseed rape.