| Euphorbia tirucalli, named rubber euphorbia, milk bush, is a species of Euphorbiaceae. It has multi-usage and multi-function. It has being used as traditional medicine in Africa and South Africa, as well as in some countries of Southeast Asia, an attractive indoors and landscape ornamental tree.Recently it has been made more important and popular as energy resources plant of agro-forestry in dry and semi-dry regions. Growing in rather arid zones as well as mesophytic zones, the species makes a good living fence post, fire-prevent belts rounding forests, and water and soil conservation forest. The wood is used for rafters, toys and veneer, resource of active charcoal, and other industries row materials. Lots of researches and studies on this species have been done on chemical compositions of latex and whole plant, cell suspension culture and energy products in foreign countries. However, since the species was introduced to Hainan and Yunan provinces, China, as an ornamental tree, little work has been done concerning its propagation, utilization of medicine and energy sources. Because of that the research project of "Introduction and cultivation techniques of Euphorbia tirucallf was listed as "the important project of introducing advanced technologies of foreign agriculture" by the State forestry Administration in 1999. The most important work of the project is to conserve and propagate the limited introduced materials of this species, then to domesticate, develop and utilize the plant. Therefore, the author of this paper has conducted a series of experiments firstly in China on the species: such as the establishment of fast propagation system, including cutting and tissue culture by using of materials introduced from American, Hainan, and Yunan. Based on the propagationsystem, researches on cold resistant mutant, polypoild, establishment of gene transformation system were conducted. Also, biological characteristics, latex composition and RAPD analysis on plantlets regenerating from different ways had been done. The results from the researches would provide a significant basis and practical technologies for the development and utilization of the species, which detailed as following:1 Cutting propagation and Successful establishment of in vitro propagation system of Euphorbia tirucalli. Factors such as provenance, cutting type, media, cutting time and plant hormones which affect on rooting were analyzed and discussed; Effects of different factors such as explants type, growth regulator and non-growth regulator on germination of buds, callus formation and shoot regeneration, rooting and transplant survival of plantlets were studied . And optimum media, culture conditions and procedure for fast propagation were selected.(1) Cuttings of Euphorbia tirucalli without treatment of plant growth regulator, could root easily, and could be planted in Spring, Summer and Autumn on different media, however plant growth regulator such as IBA, NAA, and ABT6 can enhance rooting and improve the quality of roots.(2) There were differences in days to initial rooting, rooting duration among cuttings from different provenances. Cuttings from American had a long time to initial rooting and a long rooting duration. But at the end of rooting period, the rooting percentage of cuttings from the three provenances has little difference.(3) Cutting type, media, and exohormone affected the rooting percentage and roots quality. Low concentration (0.1-0.25mg/l) of IBA, NAA, ABT6, enhanced rooting of the cuttings. One-year semi-hard and hard cuttings planted in the media composed of" sand+ Pearlite+ Humus soil=1+1+1" had the highest rooting percentage(more than 90%), the largest number ofroots(average 5 roots per cutting), and short and robust roots( 2.6 cm).(4)Calli could develop easily on MS media with cytokinins such as BA, ZT, et. al., but the calli were light-green compact (type I) and light yellow loose( type II), no plantlets were regenerated from those calli after several generation subculture. 2,4-D affected t...
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