The Preliminary Research On Establishment Of Virus-Elimination And Rapid Propagation Of Taro (Colocasia Esculenta Schott.)

Taro (Colocasia esculenta) is one type of important vegetables. Virus diseases of taro are very serious because of long-term vegetatively propagated. Ten cultivars of taro were used to study the systems on induction and propagation of virus-free micro-tube plantlets and in vitro corms. To establish the tissue culture and virus identification system, we utilized different sizes of shoot-tip as in vitro culture explants of taro. And for obtain the expanded corms of taro and the growing system we screened the the induced culture medium. We also established the field proliferation and production models for micro-tube plantlets and in vitro corms. The detailed results were as follows:1. The differentiation culture of lateral budsWe induced lateral buds by modulating the ratio of NAA and BA. The result showed that the culture medium with MS+2.0mg/L BA +0.5mg/L NAA + 3% sucrose could multiplied propagation coefficiency up to 20 folds.2. The culture of shoot-tipsWe cut shoot-tips by three different sizes at 0.8-1.0mm as the large, 0.5-0.8mm as medium, and 0.3-0.5mm as the small. from lateral buds to MS medium with different kinds and concentrations of hormones. The result showed that the induced lateral buds of the three grades shoot-tips on medium with MS+2.0mg/L 6-BA+0.2mg/L NAA+3% sucrose were more and stronger than ones on other medium.3. The detection of taro mosaic virusWe got the virus-free shoot-tips of three grades. The result showed small shoot-tip was the most effective for virus-free, the rate of virus-free was 100%. The next was medium shoop-tip, the rate of virus-free was 94.4%. The last one was large shoot-tip, the rate of virus-free was 90.9%.4.Studying technique of in vitro corm inductionStudies of in vitro corms induction showed that suitable medium is MS, 8%sucrose, 1.0mg/L BA, 0.5mg/L NAA, 6g/L agar, pH5.8; The suitable conditions were 30℃, 12h/d light. On this conditons, the rate of in vitro corms induction was 100%.5.Growth of tube plantlets and in vitro cormsIn growth methods of tube plantlets, field planting net was the best. The survival rate of its was 95%.The growth of in vitro corms: In four different bases (sand, vermiculite, soil and sand:vermiculite:soil=1:1:1), survival rate of virus-free in vitro corms in vermiculite was the highest. The survival rates of big corms, medium ones and small ones were 100%, 96.92% and 88.75%.6. The contrast between micro-tube plantlets and in vitro corms in the field performance1) Contrast between non virus-free tube plantlets and in vitro corms in fieldThe result showed the corms and grade cormels of tube plantlets were smaller than normal types, the yield of grade cormels was low, the shape of corms became from round to oblate. The corm yield and total yield of tube corms cultivation were higher than grade corms of normal types.2) Field trial test of virus-free in vitro cormsThe mass of simple second grade corm of virus-free in vitro corms was lower than normal types by 0.6g. The number of second grade corms of virus-free in vitro corms was lower than normal types by 0.8. Except of the mass and number of simple second grade corm, other data of virus-free in vitro corms were higher than normal types. Among those data, the mass of simple first grade corm, the mass of first grade corms per plant and yield of grade corms of virus-free in vitro corms were higher than type ones by 40.54%, 27.88% and 20.14%.