Drought priming combined with additional potassium application enhances wheat tolerance to post-anthesis drought via...

Increasing drought events pose a significant threat to crop yields. Drought priming has emerged as a promising technique for enhancing plant tolerance to post-anthesis drought stress; however, its effectiveness in combination with other interventions remains underexplored. A pot experiment was conducted to evaluate the effects of drought priming combined with additional potassium (K) application on wheat (Triticum aestivum L.) tolerance to post-anthesis drought stress. The study examined the influence of these treatments on gas exchange parameters, leaf moisture metrics, osmotic adjustment, anatomical traits, gene expression levels, and grain yield. The results indicated that a seven-day post-anthesis drought markedly reduced grain yield, primarily due to stomatal limitations on photosynthesis resulting from leaf water loss. Drought priming and K application improved wheat performance by enhancing osmotic adjustment (OA) and leaf hydraulic conductance (K_L), respectively, although the underlying mechanisms differed. Both treatments promoted OA by increasing the accumulation of proline and glycine betaine through the upregulation of TaP5CS and TaBADH. Drought priming enhanced K_L via the upregulation of AQP genes, whereas K application increased K_L by enlarging the bundle sheath size of the minor veins. Moreover, the combination of drought priming and K application synergistically promoted OA and K_L, thereby minimizing leaf water loss and reducing stomatal limitations on photosynthesis, which maximized grain yield under drought conditions. These findings demonstrate that additional K application following drought priming can significantly enhance priming-induced drought tolerance in wheat, suggesting that additional K after drought priming is a promising strategy for improving crop yield under water-limited conditions.