The growth of P. helferi was studied using the DFT involving
nutrient solutions at five different EC levels from 0.4 mS/cm to
2.0 mS/cm. It was found that the differing EC levels significantly
affected the height and shoot number of P. helferi but did not
significantly affect the diameter of the shrubs (Table 6). The specimens
of P. helferi cultured at EC levels of 1.6 mS/cm had the greatest
growth with respect to their height with a significant increase in
the number of shoots (Table 6). After 6 wk, the specimens of
P. helferi cultivated at the EC level of 1.6 mS/cm began to grow better
than those under the other treatments. The height increased to be
7.47 ± 0.44 cm taller than the plants of other treatments experiment
which was significant until the experiment was terminated at
10 wk.