Combined application of nitrogen and potassium reduces seed yield loss of oilseed rape caused by Sclerotinia stem rot disease. (20th October 2020) - Zhang, Jianglin
Abstract: Sclerotinia stem rot (SSR) is a major fungal disease of oilseed rape ( Brassica napus L.) that causes severe yield losses. Nutrient management is crucial for protecting crops against SSR. Two‐yr field trials combined four levels of N application (0, 90, 180, and 270 kg N ha −1 ) and four levels of K application (0, 60, 120, and 180 kg ha −1 K2 O) to investigate their interaction effects on SSR disease incidence and seed yield loss caused by SSR. Compared to the sole application of N, the combined application of N and K decreased the SSR disease incidence by 9.9–24.4 and 17.4–37.9% in 2016–2017 and 2018–2019, respectively. N application increased the severity of SSR only at lower K application rates (0 and 60 kg ha −1 K2 O). Additionally, compared to the sole application of N, the co‐application of N and K dramatically decreased the total yield loss rate (TYLR), by 31.1–60.9 and 19.2–60.3% in 2016–2017 and 2018–2019, respectively. The seed yield response to N uptake was dependent on the level of K application. However, SSR disease dramatically decreased the nutrients use efficiency. Nitrogen and K supply showed synergistic interaction effects on N and K recovery efficiency. These results emphasized the importance of N and K co‐application on reducing the yield loss caused by SSR infection. For a stabilized seed yield, an adequate N (180 kg ha −1 ) application rate combined with a slightly high K application rate (120–180 kg ha −1 ) represents a feasible nutrient management strategy for oilseed rape against SSR disease.