Establishment of micropropagation systems for clean planting materials of taro (Colocasia esculenta L. Schott)

Taro is important not only as carbohydrate source but also because of the health benefits and other uses that can be derived from it. Dissemination of the NSIC-approved taro varieties is limited due to the slow conventional propagation method. Moreover, being vegetatively propagated, carry-over of disease-causing microorganisms always exists which contributes to yield reduction. This study was undertaken to develop suitable micropropagation systems but maintaining character stability of regenerated plants. Four NSIC-approved varieties namely VG1, VG2, NSIC G9 and NSIC G10 were used as test materials and micropropagated in vitro using different explants types in modified MS medium. Rapid ex vitro propagation trials of potted tissue culture-derived plants were also explored. Results showed that for the initial culture, the half shoot tip explants (T2) were better than whole (T1) and quarter explants (T3). Moreover, during the second micropropagation cycle using modified MS medium, differences in response of the three types of explant in vitro conditions were observed in the varieties used. VG2, NSIC G9 and NSIC G10 produced multiple shoots in T2 and T3 but only one in T1 (control). On the other hand, VG1 produced only one shoot regardless of explants type. It was also observed that all the varieties exhibited earlier and higher percentage shoot formation in T2 and T3 than in T1. In addition, percent root initiation in VG1 was not affected by treatment but its formation was delayed in T2. With the other three varieties, percent root initiation was highest in T2 and lowest in T1. The findings imply that subdividing the in vitro taro stock plants into several sections can be done to enhance micropropagation technique. In vitro plantlets can be potted out in 3-4 weeks from subculture. After four to five months from potting out, the tissue cultured plants can be successfully micropropagated under nursery condition using corm slices and nodal cuttings of runners.