2.1.2. Culture system
2.1.2.1. Culture system design. The in vitro hydroponic
culture system in this study consists of: (1) a cylindered
polypropylene capped box (Dai Dong Tien Plastics Company,
Vietnam, manufacture code: L621), used as culture vessel
(11.5 cm in diameter, 8.5 cm in height); (2) circular carrier
substrate [cotton layer (Bach Tuyet, Vietnam) or filter paper
(OSI, France)], served as a medium container and a substrate
for potato plantlets’ development (11.4 cm in diameter, 0.2 cm
in thickness); (3) polypropylene ring derived from nylon bag,
helping fix the carrier sheets and keep it above the liquid
medium level (36 cm in length, 2 cm in large, 0.05 cm in
thickness); (4) carrier sheets derived from the cap of the plastic
box, supporting the carrier substrate on the polypropylene rings
(11.4 cm in diameter, 0.2 cm in thickness, half of a 1-cm in
diameter circle was also pierced at the edge of the sheets so that
the capillary robe can go through); (5) a short cotton capillary
robe, transporting and distributing the liquid medium from the
bottom of the box up to the storeys on top (4 cm in length).
These parts were sterilized separately at 1218C, 1 atm, for
30 min and set up under aseptic conditions (Fig. 1).