Negative Pressure Fertigation Improves Tobacco Performance and Water Use Efficiency Through Regulating Potassium Uptake and Leaf Gas Exchange

ABSTRACT Improving water resource management is crucial for addressing irrigation water limitations and enhancing fertilizer use efficiency, thereby advancing sustainable agriculture. Negative pressure irrigation (NPI) is an innovative subsurface irrigation technology that has shown beneficial effects on agricultural production. However, the effects of negative pressure fertigation (NPF) on crop growth and the efficiency of water and fertilizer utilization have not been fully explored. Pot experiments were conducted to evaluate the effects of NPF on tobacco growth, water use efficiency (WUE), leaf potassium (K) content and nutrient uptake under three treatments: surface irrigation with surface K application (SIS), NPI with surface K application (NPS) and NPF. Compared with SIS, NPS and NPF reduced plant water consumption by 20%–24% and 12%–17%, respectively, while increasing WUE by 0.05%–23% and 7%–19%, respectively. In contrast to SIS and NPS, NPF did not negatively impact plant yield but improved leaf gas exchange parameters, such as increased photosynthetic rates, while slightly reducing stomatal conductance and transpiration rates, resulting in higher intrinsic and instantaneous WUE. Moreover, NPF increased the leaf K content and optimized the N:K ratio response, thereby improving tobacco quality. Overall, our results demonstrate that NPF could improve crop performance and resource use efficiency, highlighting its potential as a sustainable agricultural practice.