STIMULATION OF EMERGENCE OF ROOT APICAL MERISTEMS IN HORSERADISH HAIRY ROOT BY AUXIN SUPPLEMENTATION AND ITS KINETIC-MODEL

1-Naphthaleneacetic acid (NAA) in the medium strongly inhibited horser adish hairy root elongation. In batch culture, NAA in the medium was a bsorbed by the root at the beginning of the culture (0-4 d). After the depletion of NAA, root apical meristems emerged, and then the growth rate of the root increased dramatically. The batch culture with 1 x 10 (-3) kg/m3 of NAA reached the highest biomass, 10.9 kg-dry weight/m3 a t 21 d. Modificaton of a kinetic model previously developed resulted i n a favorable fit with the growth curve of horseradish hairy root trea ted with NAA. Furthermore, in repeated batch culture, the NAA-treated root culture exhibited a 1.7-fold increase in dry weight, 57 kg/m3 at 40 d, compared with that of no NAA-treated root. The modified kinetic model also correlated well with the experimental results in repeated b atch culture.