2.2. Plant sampling and phenotyping

Three populations (sites) were sampled (Figure 2; Table S1). The numbers of individuals at each site were 7, 6, and 7 in SAS habitat and 6, 6, and 8 in SS habitat for P. australis and 8, 6, and 7 in SAS habitat and 7, 7, and 6 in SS habitat for P. hirsuta. All the individuals sampled were separated by a minimum of 30 m to prevent sampling members of the same clone.

Sampling locations of Phragmites australis and Phragmites hirsuta in two habitats. Different habitats are indicated by distinct symbols (triangle, saline-alkaline meadow soil (SAS); trapezoid, sandy soil (SS); filled symbols indicate P. hirsuta).

To identify the number of chromosomes, root tips of all samples that were produced from rhizome-grown plants were taken for cytological analysis using an epifluorescence Olympus BX61 microscope.

The aboveground parts were harvested when the individuals had reached maximum biomass by late September, 2022. All the traits of 60 randomly selected individuals from each habitat (20 at each site) were noted. Internode length refers to the length between the 5th and 6th nodes from the top. After the plants were divided into organs, all of them were dried at 80°C to a constant weight, and the dry weight was determined. Three mature, fresh leaves from each one were scanned on an LI-3100 leaf area meter (Li-Cor, Lincoln, NE, USA), oven dried, and weighed to determine specific leaf area [SLA, leaf area (cm²)/leaf biomass (g)].