The relative competition intensity (RCI) of different functional traits was calculated by using following equation (Gruntman et al., 2014, He et al., 2012) between WT and WC under different nitrogen and water treatments.
\begin{equation} RCI=\frac{A_{\text{mix}}-A_{\text{mono}}}{A_{\text{mix}}+A_{\text{mono}}}\nonumber \\ \end{equation}
Where Amix is the trait value of either WT or WC in the mixed culture, while Amono is the trait value of either WT or WC in the monoculture. RCI values range from -1 to 1. Negative values indicate competition; positive values indicate facilitation; 0 value means neither competitive nor facilitative interactions.
The plasticity index (PI) of functional traits was calculated by using equation (Funk, 2008, Lamarque et al., 2013) to determine the range of phenotypic plasticity of different functional traits of WT and WC under different nitrogen and water treatments within mixed culture.
\begin{equation} P_{I}=\frac{Maximum\ value-Minimum\ value}{\text{Maximum\ value}}\nonumber \\ \end{equation}
where maximum and minimum value are the maximum and minimum value of one functional trait of WT or WC grown in mixed culture under each treatment. The value of PIranges from 0 to 1, where one represented the highest PI.