抄録
Potato productivity and water use efficiency (WUE) in semi-arid regions are strongly influenced by the timing of drought stress, yet the stage-specific mechanisms governing yield formation remain insufficiently understood. A field experiment was conducted to evaluate the effects of drought imposed at the seedling, tuber initiation, tuber bulking, and starch accumulation stages on crop growth, biomass partitioning, yield formation, and WUE. Potato responses exhibited pronounced stage dependence. Early-season drought triggered compensatory growth after rewatering, partially restoring biomass production and improving WUE without significant yield loss. In contrast, drought during tuber initiation and tuber bulking represented the critical water-sensitive period, markedly suppressing canopy development, reducing dry matter allocation to tubers, and consequently causing the greatest yield penalties. Drought during the starch accumulation stage had comparatively minor effects on yield, indicating greater tolerance to late-season water deficits. These results demonstrate that the impacts of drought on potato productivity are governed by growth stage-dependent shifts in biomass allocation and sink development rather than water deficit alone. Optimizing irrigation according to stage-specific water demand—allowing moderate water deficits during early growth, maintaining adequate water supply during tuber initiation and bulking, and applying deficit irrigation during late growth—can improve the coordination between yield formation and water use efficiency. This study establishes a physiological basis for stage-specific deficit irrigation and provides a mechanistic framework for precision water management in potato production under water-limited conditions.
