Continuous subcultures effect on Gynura procumbens Lour. (Merr.) branch number and root length

Subculture is significant for maintaining the stock of roots to determine the proliferation of roots. Subcultures are needed to avoid an accumulation of toxic in the culture medium and container. In addition, there have been no reports regarding the maintenance of the adventitious root of Gynura procumbens through the subculture process. Therefore, we carried out this study is to determine the proliferation characters of adventitious root piece explants by observing the total of root branches and measure the length of roots during continued subcultures in a solid medium. The adventitious root of G. procumbens regenerated from leaf explant in solid MS medium supplemented with 5 mg/L indole-3-butyric acid (IBA). The root pieces were subcultured with the same medium composition. Moreover, the subculture period was performed 5th time with a culture interval every 3 weeks. The result has shown that the subculture period affects a total of lateral root branches. The highest mean total of branches was achieved at the 4th subculture period (48.0±7.58), but not significant with the 1st subculture period (47.2±9.00). The length of the roots was affected by a total of root branches. The length of the roots was affected by a total of branches. The highest total roots branch on the 4th subculture has been dominated by high numbers root length with a score of 1 (31±2.04). On the other hand, the 1st subculture has dominated by high numbers root length with a score of 3 (26±0.83). The saturated concentration of IBA in medium and specific response from roots explant tissues might cause different root proliferation during continued subcultures. In conclusion, continued subcultures of adventitious roots on certain periods can produce separate roots proliferation characters.