Water and fertilizer supply can affect the processes of assimilate production (source) and assimilate accumulation (sink), thereby causing differences in potato yield. However, little is known about the coupling effects of irrigation amount and potassium rate on potato tuber yield and its potential source-sink relationships. The objective of this study was to quantify how water and potassium supplies affected the source-sink relationships of drip-fertigated potato after tuber emergence. A two-year field experiment was conducted during the potato growing seasons of 2019 and 2020, with three irrigation levels (W1: 60% ET_c, W2: 80% ET_c and W3: 100% ET_c, where ET_c is the crop water requirements) and four potassium rates (K0: 0 kg ha^-1, K1: 135 kg ha^-1, K2: 270 kg ha^-1 and K3: 405 kg ha^-1). The results showed that compared with K0, the treatments viz., K1, K2 and K3 increased average tuber yield by 1.3%, 17.3% and 15.5% in 2019 and 10.7%, 24.0% and 19.3% in 2020, respectively. However, compared with W3, the treatments viz., W1 and W2 reduced the average tuber yield by 8.0% and 12.9% in 2019 and 8.9% and 14.7% in 2020, respectively. The beta sigmoid growth function well fitted the relationship of source capacity and sink capacity. The source capacity and source activity increased with the increase of potassium rate under W2 and W3 in 2019 and under W3 in 2020, while the sink capacity and sink activity first increased and then declined with the increasing potassium rate. Increasing water and potassium supply generally increased the vegetative growth and tuber growth time. The tuber growth rate first increased and then decreased with the increase of potassium rate, while it increased with the increasing irrigation amount. The sink-source ratio decreased with the increase of potassium rate, but there was no significant difference between K1 and K2, and the sink-source ratio under K3 was significantly lower than that in the other potassium treatments. It was concluded that potato was in source-sink balance under K1 and K2, but not under K3. The quantitative approach produced parameters that characterized the differences of source and sink capacity in response to various water and potassium supplies. Sufficient irrigation (W3) with moderate potassium application (K2) increased potato yield mainly by maintaining its source-sink balance.

水肥供应会影响同化生产（源）和同化积累（汇）的过程，从而造成马铃薯产量的差异。然而，关于灌溉量和施钾量对马铃薯块茎产量的耦合效应及其潜在的源库关系知之甚少。本研究的目的是量化水和钾供应如何影响滴灌马铃薯块茎出苗后的源库关系。在 2019 年和 2020 年马铃薯生长季节进行了为期两年的田间试验，三个灌溉水平（W1：60% ET _c，W2：80% ET _c和 W3：100% ET _c，其中 ET _c是作物需水量）和四种钾含量（K0：0 kg ha^-1，K1：135 kg ha ^-1，K2：270 kg ha ^-1和 K3：405 kg ha ^-1 )。结果表明，与K0相比，K1、K2和K3处理2019年平均块茎产量分别增加1.3%、17.3%和15.5%，2020年分别增加10.7%、24.0%和19.3%。然而，与 W3 相比，治疗即.、W1 和 W2 分别使 2019 年和 2020 年的平均块茎产量降低了 8.0% 和 12.9% 和 8.9% 和 14.7%。β sigmoid 增长函数很好地拟合了源容量和汇容量的关系。2019年W2和W3下以及2020年W3下，源容量和源活度随着施钾量的增加而增加，而库容量和库活度随着施钾量的增加先增加后下降。增加水和钾的供应通常会增加营养生长和块茎生长时间。块茎生长率随施钾量的增加先增加后减少，随灌水量的增加而增加。库源比随着施钾量的增加而降低，但K1和K2之间没有显着差异，K3 下的库源比显着低于其他钾处理。得出结论，马铃薯在 K1 和 K2 下处于源库平衡，但在 K3 下不处于源库平衡。定量方法产生的参数描述了响应不同水和钾供应的源和汇容量差异。充足的灌溉（W3）和适度的钾肥（K2）主要通过维持其源库平衡来增加马铃薯产量。