| Hippeastrum vittatum Herb., which has outstanding, showy flowers and slim foliage with easy cultivation and management, is one of the most important bulbous ornamentals with extremely high ornamental values and popular among customers. Because of few variety and low quality of domestic Hippeastrum bulbs at present, most of which depend on import from abroad in production resulting in high price. Besides the low natural propagation rate and most of the varieties are not able to breed bulblet. Thus, it’s the key to improve the Hippeastrum bulbs quality via establishing an high quality and efficient bulb reproduction technical system. Culture in vitro technique is widely used in production of superior materials in large scale. However, from present research results, including Netherlands and other countries which have developed flower industry, it is short of culture in vitro technique of Hippeastrum, the induction rate of various explants was at an extreme low level, even0. Traditional scaling propagation of Hippeastrum bulbs is widely used at present, resulting in high frequency of virus.’Red lion’, the main cultivar of Hippeastrum in international market at present, was used in this experiment in order to research in the effect of Hippeastrum regeneration by three different parts of explants:scales, scape and petal, which objective is to lay the foundation for establishing efficient regeneration technical system of Hippeastrum cultured in vitro. The main results were as followed:1. For scales as explants, the explants of5mm2square expanded after3days of culture and turned brown at the same time. After incubation for30days, initiation rate kept the same, and the explants did not expand or change any more.100days later, bulblet began to form on the callus. Thus, the optimum medium for scales induction was MS+NAA2mg/L+BA2mg/L+VB10.5mg/L, pH5.8, the initiation rate on which was46.67%, and there was bulblet formation on callus induced only on this medium after120d. When the concentration of BA was2.5mg/L, the initiation rate increased as higher concentration of NAA, and as the concentration of NAA was high and BA/NAA close to1, the initiation rate was high. NAA, pH and VB1had a significant influence on explants initiation extremely, they were sorted from strong as:NAA> pH> VB1. As far as one bulb is concerned, the scale cuts which Located in inner and middle scales and in the basal part of the bulb had the highest initiation rate.2. Two pathways were found in this study from inflorescence regeneration in vitro, one of which is callus induction to adventitious shoot with root formation, the other is adventitious shoot, plantlet or bulblet formation on explants directly. The MS medium added2.0mg/L NAA and4.0mg/L BA was conductive to the pathway from adventitious shoot induction to plantlet directly, while MS added4.0mg/L NAA and4.0mg/L BA was more inclined to callus induction and then to accomplish organ initiation.Bulblet was obtained from petal explants for the first time. The initiation rate of bulblet on petal explants was highest, which was15.38%when cultured on MS added2.0mg/L NAA and4.0mg/L BA. The petals began to initiate callus after40days, adventitious shoot occurred after50days, and when incubation to100days, the number of plantlet and adventitious shoots formed on petal slices was stable; and the scapes had the optimum inducement effect on MS added2.0mg/L NAA and4.0mg/L BA. The inflorescence explants could be transferred on the same media, which would make the adventitious shoot form rich roots and finally form the bulblets.For petals, dark culture actually increased initiation ratio and resulted in well developed bulblets in a considerable number. However, for scapes, dark condition induced the highest number of adventitious shoot from one scape segment.3. MS+NAA0.5mg/L+BA2mg/L was the optimal medium for subculture of Hippeastrum.0.2g/L Vc added to media would inhibit brown stain of explants cultured in vitro and was good to explants induction. |
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