Development of micropropagated plants from different clones of Senecio x hybridus in relation to BAP concentration and temperature in vitro

Summary

Selected mature seedling plants were used as stock plants and about half of them were successfully micropropagated. There was no correlation between the ability of petiole expiants to form adventitious shoots and the capacity of these shoots to multiply. Growth and development varied between the micropropagated clones, originating from one seedling each. The colour of the flowers was always constant within a clone. Developmental time, foliage height and the numbers of shoots, leaves and flowers were influenced by the BAP concentration used in vitro. The temperature during the in vitro phase affected the development time and the height of foliage and inflorescences. Increased BAP concentration (from 0 or 0.1 mg l^?1 to 1 mg H) resulted in plants with a longer development time to anthesis and more shoots, leaves and flowers. Plants raised on 5 mg l^?1 BAP developed slowly, resulting in stunted growth, low foliage height, few leaves and flowers. Consequently, it is possible to use the BAP concentration in vitro to regulate the growth of the progeny crop. After transfer to soil in a growth chamber, plants grown at 10°C in vitro flowered earlier, and had lower foliage and higher inflorescences than plants grown at 21°C. This observation indicates that flowering may be promoted by low temperatures in vitro.