Seed yield response of ‘Qingyin No. 1’ oats to nitrogen, phosphorus, and potassium fertilizers in the alpine zone

To clarify the effects of nitrogen, phosphorus, and potassium fertilizer on the seed yield of Avena sativa in the alpine area of the Qinghai–Tibet Plateau, a single application experiment of nitrogen, phosphorus, and potassium was set up in Huangzhong District, Xining City, Qinghai Province. Three fertilization levels were used, that is, nitrogen fertilizer levels (N₀, N₃₀, N₄₅, N₆₀, N₇₅, N₉₀ and N₁₀₅), phosphate fertilizer levels (P₀, P₁₅, P₃₀, P₄₅, P₆₀, P₇₅ and P₉₀), and potassium fertilizer levels (K₀,K₁₀, K₂₀, K₃₀, K₄₀, K₅₀ and K₆₀), to study the effects of nitrogen, phosphorus, and potassium on the yield of ‘Qingyin No. 1’ oats. This was conducted with the aim to achieving an optimal fertilization level, improving of the fertilizer management technology of this variety in cultivation, and providing scientific guidance for the application ratio of fertilizer in the production of oat seeds in Qinghai region. The results have shown that nitrogen, phosphorus, and potassium fertilizers were treated with 60, 60, and 50 kg·ha⁻¹, reaching 4 358.6, 6 285.0, and 6 729.1 kg·ha⁻¹. Potassium fertilizer had the most pronounced effect on oat seed yield. Nitrogen fertilizer could significantly increase the number of oat paniclelets, inflorescence length, and thousand kerner weight. Phosphate fertilizer could promote the effective tillering, grain width, and monoseque grain weight of oats. Meanwhile, potassium fertilizer could help increase the effective tiller count, grain length, grain width, monoseque grain weight, and thousand kerner weight. The direct effect of grain width and panicle number on seed yield was the most pronounced at the level of single application of nitrogen, phosphorus, and potassium. The number of flowers and grain width had a pronounced gain effect on seed yield through indirect effects on other yield traits. In the seed production of ‘Qingyin No. 1’ oat in high and cold areas, application of potassium fertilizer can effectively increase the seed yield of ‘Qingyin No. 1’ oats.