Nitrogen and Phosphorus Limitation Fails to Diminish Aegilops tauschii’s Competitive Suppression of Wheat

Aegilops tauschii poses a significant threat to winter wheat production in China. Understanding the relationship between nitrogen (N) and phosphorus (P) availability and the invasive competitiveness of A. tauschii is crucial for developing effective control strategies. This study employed a de Wit substitution method in a controlled pot experiment to investigate the impact of regulated soil N and P availability (via sucrose, gypsum, and their combination) on A. tauschii and wheat. Results showed that limiting N and P resources inhibited the growth of both A. tauschii and wheat, reducing chlorophyll content, plant height, and total biomass. While the sucrose + gypsum combination had the strongest inhibitory effect, A. tauschii exhibited greater adaptability to low-nutrient stress than wheat. Under mixed conditions, A. tauschii had a significantly higher root mass ratio (RMR) than wheat, and under N-limiting conditions, the “supply precedence theory” was supported. A. tauschii’s competitive balance index remained consistently positive regardless of sucrose or gypsum addition, demonstrating its resilience to N and P limitation. The competitive inhibition of wheat by A. tauschii remained unaffected by N and P limitation, likely due to its efficient nutrient utilization strategy. Interestingly, the addition of sucrose and gypsum did not significantly alter soil physicochemical properties, suggesting that A. tauschii’s competitive advantage primarily stems from efficient nutrient use rather than soil dependence. This explains its continued competitive dominance and suppression of wheat under nutrient-limited conditions. This research provides a theoretical foundation for understanding A. tauschii’s invasion mechanisms and developing effective prevention and control strategies.