Effects of soil amendments using potassium in elevating resistance against wheat blast disease

Potassium (K) is unique among the essential nutrient elements for its diversified role in plant metabolic processes. Potassium improves crop output, protects the crop from diseases and insect-pest infestation, prevents lodging, and reduces the effects of terminal heat stress. Based on this information, it was hypothesized that K will enhance host plant resistance and blast control while increasing yields. A pot experiment was conducted by artificially inoculating Magnaporthe oryzae Triticum (MoT) on a susceptible wheat (Triticum aestivum L.) variety (BARI Gom-26) to determine the effect of soil application of K on blast disease management and the growth and yield. The experiment was carried out in separate plastic pots containing 18kg of virgin soil at the net house of the farm of the Bangladesh Institute of Nuclear Agriculture headquarters, Mymensingh, for two growing seasons of 2018-19 and 2019-20 following a completely randomized design with five treatments and three replications. The dose for soil application were 0, 50, 75, 100 and 125 K kg ha-1, respectively. Disease incidence (%) and severity (%) of wheat blast were evaluated at 11, 13 and 15 days after inoculation (DAI). At 15 DAI, the highest disease incidence (95.45%) was found in absolute control followed by K0 (0 kg K ha−1) (91.98%) and the lowest blast incidence (64.49%) was found in K4 (125kg K ha−1) which was statistically similar with K3 (100kg K ha−1) (70.87%). At 15 DAI, the highest blast severity matrix (90%) was found in absolute control followed by K0 (0 kg K ha−1) (76.02%) and the lowest blast incidence (46.18%) was found in K4 (125kg K ha−1) which was significantly different with others. Among the treatments, 125 kg K ha-1 produced the highest grain yield (26.97 g pot-1) and the lowest (5.79 g pot-1) was found from the absolute control. Flag leaf samples were randomly collected before head emergence from each pot and analyzed in the laboratory for plant nutrient content. The K concentration of flag leaves sample ranged from 1.71% to 5.51% with the average concentration of 3.02%, where the highest K content (%) was recorded in K4 (5.51%) and the lowest was found in absolute control (1.71%). Potassium fertilization appeared to reduce the severity and improve yield of wheat. Correlations suggested that improving dry matter production and K uptakes at the boot stage by K fertilization can reduce severity later in the growing season and increase wheat grain yield. It can be concluded that high K concentration on leaf tissue was important to decrease wheat blast symptom.