Four selected influential factors—tissue length, salinity, part
of the thallus, and density—were subsequently investigated for
40 days in a 250-mL flask with the arm at the bottom for
aeration supply around 35 rpm. The best treatment of each
factor was then used in the next experiment. The other
conditions used 25 lmol m2 s
1 of light intensity and
12L:12D of photoperiod at a temperature of 25 6 28C. Modified
Grund’s Medium (Mensi et al., 2011) was supplied into the
flasks every 10 days during water exchange. Each experiment
was done with three replications. In the meantime, 10 tissues
from each replicate were randomly selected to measure the
length of the main segment and new branch and then to count
the number of new branches. The total biomass of all tissues
from each replicate was measured. The sampling tissues were
then returned to continue the culture. The details of the
experiments are described in the subsequent sections.