Aims Climate warming and agricultural non-point source pollution both resulting from anthropogenic activities have been projected to affect plant reproduction and growth in wetlands worldwide. In order to predict and mitigate impacts of these anthropogenic activities, it is important to investigate how marsh plants respond to such environmental changes.

Methods In this study, Bolboschoenus planiculmis, a tuberous sedge with a wide distribution range in Eurasia, was selected to examine the effect of air temperature changes (15, 20 and 25 degrees C over 24 h; 20/10 and 30/15 degrees C, day/night) and K supply (0, 1, 3, 9 and 18 mmol/L) on its reproductive and growth traits in climate chambers.

Important Findings We found that high constant temperatures (20 and 25 degrees C) were more beneficial for tuberization of B. planiculmis than high alternating temperatures (30/15 degrees C), whereas aboveground biomass and shoot height were generally largest at high temperatures (30/15 and 25 degrees C). Both reproductive and growth traits of B. planiculmis showed hump-shaped relationships with K supply, with an optimum K concentration of around 1-3 mmol/L.The combination of high constant temperatures and optimal K concentrations promoted reproductive traits the most, whereas the combination of higher temperatures (30/15 and 25 degrees C) and K concentrations up to 9 mmol/L increased growth traits only. We therefore conclude that population abundance of B. planiculmis might benefit from global warming and the additional K supply.