Nutrient concentration
A recirculation system incorporating a deep-flow technique
(DFT) was set up in a greenhouse using KMITL 2 formula prepared
as presented in Table 1. The experiment used a completely randomized
design, which included three replications with 15 samples
per replication. Five electric conductivity (EC) levels of nutrient
solution, (0.4 mS/cm, 0.8 mS/cm, 1.2 mS/cm, 1.6 mS/cm and 2.0 mS/
cm) were used to investigate the growth performance of P. helferi.
The hydroponics system used fifteen 2 m-long polyvinylchloride
pipes, each 5 cmin diameter, and 15 evenly spaced holes, each 5 cm
in diameter, were made in each pipe into which the plant culture
pots were inserted. Plants of a uniform size were selected and
transferred into the hydroponics system at 60% humidity after
running a test on the system for 1 d.