2.3.1 Relative Water Content
The relative water content of S. hieraciifolia and T. parvula shoots were measured according to Castillo (1996). After shoot fresh weight (FW) was immediately noted, the samples were incubated for at 4°C 16 h into distilled water. Shoots were then blotted and shoot turgid weight (TW) was measured. To measure the shoot dry weight (DW), samples were continuously incubated in an oven at 80 °C until achieving a constant dry weight. The dry weights were recorded. The shoot RWC was calculated using following formula: RWC (%) = (FW- DW) / (TW-DW) x 100