| Two (Colocasia esculenta L.Shott) is a kind of very important vegetable and medicinal plant, which has been cultivated in China for a long history. Up to now, taro is found to be one of the most salinity-tolerant vegetables in the world. Long period cultivation of taro will decrease the salinization degree of soil. So, it is useful in exploiting bench and sands.In conventional cultivation, taro reproduces through corms which results in low reproductive efficiency, difficulties in transportation and emergence of Dasheen Mosaic Virus(DMV). As a result of DMV, yield and quality of taro is decreased yearly which now is the most serious problem in practice. Getting plantlets in vitro through shoot-tip culture and reproduction in a short time is the effective and acknowleged method for solving this problem. But plantlets are soon faced with such new problems as low transplanting survival rate, difficulty in long distance transportation, being infected by DMV again, etc. Microcorm is the effective method in improving micropropagation system though they are need to be induced further.In order to improve the techniques of micropropagation and construction efficiency and practical reproduction system of virus-free taro, we devoted five time to study the key techniques and the mechanism in construction taro reproduction system. The results are as follows:1. Field survey of Colocasia esculenta Schott cv. Honggeng-yu (HY) and Colocasia esculenta Schott var. Fuding-yu(FY) indicated that: Similar infection symptom of Dasheen mosaic virus(DMV) were found in both of the two varieties ,and the infection rate was higher than 60%. Results of electron microscope observe proved that the shape and size of causal virus found from infection leaf was similar with DMV. A preliminary conclusion is that taro of the two varieties were infected by DMV.2. TDZ (Thidiazuron) was used as cytokinin in tissue culture of taro in different genotypes. Comparing as BA, 0.1mg - L-1 TDZ was more effective in inducing germinating and developing of buds, regenerating prolific caespitose buds via organogenesis, promoting rhizogenesis and activity of root system greatly, as a result, acclimation survival rate was improved significantly. When leaf segments, cut from in vitro plantlets, were placed on MS media containing O.lmg - L-1 TDZ, adventitious buds regenerated from segments. After transferred to propagated and rooted media, adventitious buds would proliferate and come into full plantlets.3. Plantles in vitro of taro of 4 genotypes were got through shoot-tip culture. Effect of cultural way, temperature and light on mocrocorm induction were studied. Results showed:under the condition of liquid culture, 29C (light) /20C(dark) and 8 hours light time per day, the induction rate and the fresh weight of microcorm reached the highest. If the fresh weight of microcorm is more than 0.8g, the mean sprouting rate of the 4 genotypes was more than 80%.4. Study on effect of different concentration of TDZ and KNO3 on induction and development of mocrocorm of taro. Results indicated that: as compared with 5.0mg/L BA, 0.2mg/L TDZ could increase the number of microcorms of 4 genotypes as high as 45.5%, 64.0%, 23.2 and 16.8%. The max fresh weight and total fresh weight of microcorm per vessel were also increased obviously. Though 50mmol/L KNO3 was not effective on number of microcorms, it could increase the mean fresh weight and total fresh weight of microcorm per vessel as high as 12.9% and 13.9%.5. Study on effect of different concentration of Salicylic acid(SA) on induction and development of mocrocorm of taro. Results indicated that: as compared with the control, 0.5mmol/L SA in medium could increased mean fresh weight of microcorm of taro of 4 genotypes respectively as high as 21.7%, 16.1%, 17.5% and 14.3%. ,increased max fresh weight respectively as high as 12.6%, 16.0%, 11.0% and 10.5%, increased mean dry weight respectively as high as 8.1%, 8.4%, 7.2% and 9.2%. 0.5mmol/L SA could regulated the development of major of microcorms in the s...
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