Figure 5. Traits difference between different nitrogen and water treatments of Wedelia trilobata and Wedelia chinensis based on Pearson Correlation under monoculture. For each cell green, orange and red square respectively, indicate Positive, zero and negative percentage difference in the traits value between Wedelia trilobata and Wedelia chinensis under each treatment. RGRB, relative growth rate of total dry weight, RGRSl, relative growth rate of stem length, SWR, stem weight ratio, RWR, root weight ratio respectively.
WT could increase its growth and physiological performance under nitrogen and flooding treatments, particularly in the competition (Fig. 2), because Water and nitrogen are the most important factors for growth and development (Liu et al., 2018c, Tulloss and Cadenasso, 2016). Generally, the role of nitrogen along with water promotes plant growth with increasing plant height, DW, and RGRB(Čuda et al., 2017, Wang et al., 2016b); that trend was also found in this study (Table 2, Fig. 2 and Fig. 5). DW of WT was higher under mixed culture because of taller plant height and higher leaf area, that was plant strategy to cope with flooding conditions because higher plant height makes the plant able to get connect with sun light for photosynthesis process (Zhao et al., 2015) and reduce the effect of oxygen deficiency that was created by flooding conditions (Strange et al., 2018). Higher leaf area enhances its photosynthesis and transpiration capacity under flooding and nitrogen enrichment conditions (Wang et al., 2016a, Parepa et al., 2019). Therefore, WT has higher ability for resource absorption than WC and also has higher relative growth rate along with reduced resource investment per unit area under combination of nitrogen and flooding (Dalmolin et al., 2012),