The impact of nitrogen–phosphorus–potassium ratios on potato (<i>Solanum tuberosum L</i>.) Yield and variety: a case study in liangshan yi autonomous prefecture in sichuan province

Reasonable fertilization is important for promoting potato growth and increasing potato yield and quality. Rational fertilization is crucial for promoting potato growth and enhancing both yield and quality. As a major potato-producing region in China, Liangshan Yi Autonomous Prefecture still commonly faces excessive and improper fertilizer application. This study focuses on the locally predominant cultivar “Chuanliangshu 10” and adopts a fully implemented “3414” fertilizer experimental design, with nitrogen (N), phosphorus (P), and potassium (K) as the main factors, each at four levels. By analyzing the variations in potato agronomic traits, yield, and quality under different NPK ratios, this research aims to explore the optimal fertilization ratio suitable for potato cultivation in the region. The results revealed that the potato yield was greatest in the T3 treatment (N1P2K2, N 56.25 kg ha⁻¹, P₂O₅ 112.50 kg ha⁻¹, and K₂O 112.50 kg ha⁻¹). By fitting the yield data to a ternary quadratic regression model, the theoretically optimal fertilization treatment was calculated as T13 (N1P2K1, N 56.25 kg ha⁻¹, P₂O₅ 112.50 kg ha⁻¹, and K₂O 56.25 kg ha⁻¹). In the T5 treatment (N2P1K2, N 112.50 kg ha⁻¹, P₂O₅ 56.25 kg ha⁻¹, and K₂O 112.50 kg ha⁻¹), the potato plant height, emergence rate, marketable tuber ratio, dry matter content, and amino acid content were relatively balanced. Considering all the factors, the T5 treatment is recommended as the optimal fertilization ratio for potato cultivation in this region.