Bioscience Methods 2026, Vol.17, No.1, 43-56 http://bioscipublisher.com/index.php/bm 54 balance. The evaluation results show that the treatment with an appropriate potassium fertilizer dosage has the highest composite index, confirming that this potassium application level is the best in terms of balancing high yield and high quality. On the contrary, the composite indices of treatments with too low or too high potassium application are both low, as the former has insufficient yield and the latter has limited improvement in quality, resulting in a lower score. The multi-objective comprehensive evaluation provides a quantitative basis for determining the appropriate potassium application dosage for sweet potatoes, helping to break through the limitations of making fertilization decisions based solely on yield or a single indicator, and ensuring the simultaneous achievement of yield and quality goals. Based on the experimental results and comprehensive evaluation, this study has proposed the appropriate application range of potassium fertilizer in sweet potato production, and provided differentiated potassium application recommendations for different types of uses. In general, for fresh consumption-type sweet potatoes (including varieties suitable for direct boiling and consumption or baking and sale), a moderately high potassium application level should be selected. Within this range, sweet potatoes can achieve higher yields while having sufficient sugar content in the tubers, ensuring a sweet and not overly dry flavor. Adequate potassium supply can also increase the vitamin and carotene content of fresh consumption sweet potatoes, further enhancing their nutritional quality. For baking-type sweet potatoes (varieties mainly used for baking), the quality evaluation focuses on a sweet and soft texture. The potassium fertilizer management for fresh consumption-type sweet potatoes can be referred to, that is, ensuring sufficient potassium to highlight the sweetness and soft texture. In contrast, for processing-type sweet potatoes (starch type), which are mainly used for starch extraction and food processing, the requirements for dry matter and starch content are higher, while sugar content is relatively less important. Such varieties should apply a higher level of potassium fertilizer to maximize tuber starch yield and dry matter accumulation. Research shows that the recommended potassium fertilizer application rate under high-yield cultivation is approximately 200 kg K₂O/ha, which can significantly increase sweet potato yield and starch content and achieve higher economic benefits. Therefore, for sweet potato varieties aimed at starch processing, the potassium fertilizer application can be increased to a level matching the high-yield requirements (such as 200 kg K₂O/ha or so), to ensure maximum starch output and optimized economic benefits. It should be emphasized that the appropriate potassium application range for different uses of sweet potatoes is not completely separate but a range interval. It should be adjusted according to the specific characteristics of the varieties, the requirements of the target product, and the soil nutrient supply conditions. In practical applications, the interval proposed in this study can be referred to, and potassium fertilizer input can be flexibly adjusted within this range to achieve specific goals such as the sweet and delicious flavor of fresh consumption sweet potatoes or the high powder and high yield of processing sweet potatoes. When determining the potassium fertilizer application rate for sweet potatoes, both economic benefits and environmental impacts must be taken into account, and a scientifically reasonable fertilizer safety boundary should be set. Firstly, from an economic perspective, the goal should be to maximize the input-output ratio. The increase in potassium application rate must lead to an increase in yield that can compensate for the fertilizer cost and bring about an increase in net income. Research indicates that when the potassium fertilizer application rate increases from 80 to 120 kg/ha, there is no significant difference in sweet potato yield, but it increases fertilizer expenditure. Therefore, excessive potassium application will reduce economic benefits. This study also found through benefit calculation that the medium potassium application treatment achieved the highest net income, and beyond this level, the increase in unit yield is not sufficient to offset the additional fertilizer investment, resulting in a decline in economic benefits. Thus, potassium fertilizer application should have an upper limit. Applying more than the "economic optimum point" is considered an ineffective investment or even a reduction in income. Secondly, from the environmental and resource perspectives, potassium fertilizer management involves soil nutrient balance and possible environmental risks. On the one hand, insufficient potassium application over the long term will lead to excessive extraction of the potassium reserve in the soil, resulting in a negative potassium balance and subsequently affecting the production potential of subsequent crops. Meta-analysis results show that in the case of no return of sweet potato residues to the soil, more than 225 kg of potassium per hectare is required
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