Bioscience Methods 2026, Vol.17, No.1, 43-56 http://bioscipublisher.com/index.php/bm 45 the yield of sweet potato tubers. Potassium fertilizer promotes the allocation of photosynthetic products to the tubers, increases dry matter production and tuber biomass, thereby achieving yield increase (Gao et al., 2021). However, different experiments report inconsistent changes in the dry matter ratio of the tubers (i.e., the ratio of dry weight to fresh weight): some studies indicate that potassium fertilizer can increase the accumulation of starch and dry matter in the tubers, leading to an increase in the dry matter ratio of sweet potatoes (Gao et al., 2021); while other experiments observed that high amounts of potassium fertilizer (especially potassium chloride) instead reduced the dry matter ratio of the tubers and increased the moisture content of the tubers (Huang et al., 2025). This difference is partly attributed to the influence of the type of potassium fertilizer - chloride ions may inhibit starch accumulation, resulting in a decrease in the dry matter content of the potato tubers treated with KCl, while potassium sulfate (K2SO4) and other sulfate potassium sources have the effect of increasing dry matter content (Huang et al., 2025). Additionally, the optimal amount of potassium fertilizer varies depending on environmental conditions and varieties: in poor soil conditions in tropical regions, applying potassium at approximately 80 kg K ₂O/ha can achieve the best effect of increasing yield and improving quality (Singh et al., 2017); while in high-yield cultivation conditions, sweet potatoes may require a higher potassium application level (such as 150~300 kg K2O/ha) to fully exert their yield-enhancing potential (Geng et al., 2024). The reasons for these differences include soil potassium supply capacity, climate and water conditions, the characteristics of sweet potato varieties, and the nitrogen and phosphorus levels of the base fertilizer, among other factors. In summary, potassium fertilizer application should be adjusted according to specific production conditions, ensuring yield increase while also taking into account quality indicators such as the dry matter ratio of the tubers, to achieve a coordinated and unified balance between yield and quality. 2.3 Mechanism pathway of potassium's impact on sugar accumulation and sugar component composition The application of potassium fertilizer not only affects the yield and starch accumulation of sweet potatoes, but also alters the sugar accumulation and sugar component composition of the tubers by regulating the carbohydrate metabolism pathway (Gao et al., 2021). Generally speaking, adequate potassium supply helps increase the total soluble sugar content in sweet potato tubers and optimize the sugar composition ratio (Shu et al., 2024). Mechanistically, potassium levels can influence the balance of "starch-sugar" conversion: when potassium is insufficient, the carbohydrate metabolism of the plant is hindered, often resulting in abnormal accumulation of soluble sugars (such as sucrose, glucose, etc.) in the tissues while the starch synthesis is limited (Sheng et al., 2023); moderate potassium application promotes the conversion of sucrose to starch, increasing the starch concentration, and avoiding excessive sugar accumulation (Gao et al., 2021). This process involves the regulatory role of multiple key enzymes. Potassium is an activator of enzymes related to sucrose metabolism and starch synthesis. Adequate potassium supply can enhance the activity of sucrose synthase, starch synthase, and other enzymes, promoting sucrose decomposition and starch polymerization (Gao et al., 2021). In addition, potassium's influence on carbohydrate transport enzymes, conversion enzymes, etc., helps maintain the sugar concentration gradient between the source and sink, thereby regulating the distribution of sugar in various parts of the plant (Jiang et al., 2024). 3 Experimental Design and Index System 3.1 Overall design concept of potassium fertilizer gradient and uniform nutrient background This study adopts a field control experiment design, setting gradients with different potassium fertilizer application rates to explore the impact of potassium levels on sweet potato yield and quality (Geng et al., 2024). A suitable sweet potato variety (such as the fresh-keeping type variety 'Shangcui 19' or the high-starch type variety) was selected, and several potassium application levels were set on the same field (for example, no potassium application as a control, and low, medium, slightly high, and excessive potassium fertilizer treatments), forming a gradient comparison (Lv et al., 2021). The nitrogen and phosphorus nutrient inputs for all treatments remained consistent to ensure that potassium was the only variable, eliminating interference from other nutrient differences (Shu et al., 2024). To closely reflect the potassium demand characteristics of sweet potatoes in production, potassium fertilizer was applied in a phased manner: a portion of base fertilizer potassium was applied at planting, and the remaining potassium fertilizer was applied during the sweet potato covering period or the tuber expansion
RkJQdWJsaXNoZXIy MjQ4ODYzNA==