Waterlogging tolerance of the invasive plant Aegilops tauschii translates to increased competitiveness compared to Triticum aestivum.
In the cultivation of wheat (Triticum aestivum L.), waterlogging has been identified as one of the most important limiting factors. It affects the overall global wheat production as well as that for the People's Republic of China. Aegilops tauschii Coss., so far known as the main malignant weed in the wheat fields but it is unclear whether its invasiveness and competition with wheat would be affected by waterlogging. To study this, we conducted a controlled pot experiment using the De Wit replacement method. Monocultured and mixed experimental setups of A. tauschii and wheat were performed to study the effects of 0 (control), 5, 10, 15, 20 and 25 days of water stress treatments on A. tauschii growth and its competition with wheat. The results showed that in terms of morphological characteristics, the height increase of A. tauschii plants showed strong water tolerance. While the leaf area and total biomass were significantly affected by water flooding stress. In terms of physiological characteristics, A. tauschii exhibited high superoxide dismutase (SOD) activity, which promptly removed active oxygen free radicals generated by water flooding stress. This activity reduced the accumulation of thiobarbituric acid (TBARS) in the plant, and thus exhibited stronger water tolerance than wheat. In addition, regarding phenotypic plasticity, the mean plasticity index (PI) values of most morphological and physiological parameters of A. tauschii were close to those of wheat. Yet the PI values of plant height and root biomass were significantly higher than those of wheat. It indicates that the waterlogging tolerance to A. tauschii may be related to the high values of some particular traits. Finally, with the prolonged waterlogging treating time, the relative yield (RY) value of A. tauschii was always greater than 1, while for wheat, the RY value was less than 1. In addition, the competitive balance (CB) value of A. tauschii was greater than 0 and its relative competitive intensity (RCI) was less than 0. This shows that the short-term waterlogging stress changed the competition relationship between A. tauschii and wheat. In it wheat was suppressed and the competitiveness of A. tauschii was enhanced. In summary, A. tauschii have a certain degree of tolerance to waterlogging, and short-term waterlogging would promote its competition with wheat, which is expected to increase its invasion potential.