2.3 Harvest and measurement
The plant materials were harvested on May 7th, 2014 after 106 days of growth when the plant vegetative parts entered the decaying process. First, the fruit sets were collected. Second, all turions in each mesocosm were collected. The number of fruits and turions were counted. The scale leaf number of each turion was recorded. Then, the biomass of fruits and turions was determined after ovendry at 70 ℃ for 48 h. Since the scale leaf number of turion ranged from 1 to 8 in the present experiment, the turions were divided into two groups based on the scale leaf number – the oligophyllous turion (the turion with scale leaf number ≤ 4) and the pleiophyllous turion (the turion with scale leaf number > 4). This classification method for turion has been certified to be effective in discriminating its fitness since scale leaf number has a direct correlation with the turion sprouting potential (Jian et al., 2003; Qian et al., 2014). The percentage for each group was calculated.