Segmentation of plant hairy roots promotes lateral root emergence and subsequent growth

The influence of root cutting on the emergence of lateral roots was investi gated in the cultures of horseradish and madder hairy roots. The original h airy roots prepared for inoculation were cut at various distances from the tips and the resultant segments were cultivated; in flasks. It was found th at lateral roots very frequently emerged from the segments, depending on th e longitudinal positions at which the segments were obtained. To attain the effective growth, cultivation of madder hairy roots with root cutting perf ormed twice at 0 and 360 h was conducted. The emergence of lateral roots fa cilitated the growth of hairy roots owing to an increase in the number of g rowing points (GPs). The dry cell mass concentration and the number of GPs were 9.6 kg/m(3) and 1.9 x 10(7)/m(3) at 672 h of culture time, which were 3.6 and 4.9 times higher, respectively, than those In the control culture w ithout the operation.