| The rapid micropropagation technique of triploid clones of populus tomentosa (BT17,BT18,BL175,BL193)were comprehensively studied. The tissue and organs from white popular can be rapid micropropagated successfully. The factors affecting propagation, problems existing in this technique and their solutions were also described. The optimal procedure for rapid micropropagation was worked out, which provided the theoretical base and technical measures for industrial production of plantlet. Result indicated that the best time combinations of sterilizing agents are different for each clone. The optimal sterilization condition were as following: BT17:70%alcohol12s+0.1%HgCl2 9min; BT18: 70%alcohol12s +0.1%HgCl2 25min;BL175: 70%alcohol20s+0.1%HgCl2 7min; BL173: 70%alcohol5s+0.1%HgCl2 9min. The main factors affecting bud multiplication and shoot growth are nutrients and plant growth regulators besides their genetic potential. MS was found to be the most favorable to bud multiplication and shoot growth. Within certain concentration range, the number of buds was determined by BA, and the growth of shoots was determined by NAA. Bud multiplication and shoot growth were controlled by not only the absolute concentration, but also the relatively ratio of BA/NAA. The optimal mediums for bud multiplication of each clone were: BT17:MS+BA0.3mg/L+NAA0.01mg/L; BT18:MS+BA0.1mg/L+ NAA0.01mg/L;BL175:MS+BA0.3mg/L+NAA0.01mg/L;BL193:MS+BA0.9mg/L+NAA0.05mg/L; The most favorable media for shoot growth were: BT17:MS+BA0.9mg/L +NAA0.5mg/L;BT18:MS+BA0.6mg/L+NAA0.5mg/L;BL175:MS+BA0.3mg/L+NAA0.01mg/L; BL193: MS+BA0.9mg/L+NAA0.05mg/L. Study on endohormones indicated that propagation coefficient was higherwhen the content of ZRs and IAA was more. The shoot length was longer when the content of GA1/3 and IAA was higher and ABA was lower. Result showed that the content of ZRs and IAA in the vitrified plantlet was lower than that in the normal plantlet, while the content of GA1/3 and ABA was higher. The industrial and commercial micropropagation of white popular plantlet was restricted by vitrification. It was difficult for vitrified plantlet to root or to be subcultured. Study indicated that the higher the concentration of macroelement was, the more the rate of vitrified plantlets was. The correlation coefficient between the agar concentration and the vitrification rate was reverse. And the relation between intensity of light and vitrification rate was also reverse. Compared with KT, vitrification percentage caused by BA was higher. Study also found that vitrification rate was higher when combining BA with KT than that when using them along. The vitrification rate caused by cotton plug wrapped in cheese cloth was the lowest among all seal materials, including polyethylene film, plastic cover and sulfuric paper. The high cost was unfavorable for the industrial commercial production of plantlet. Study showed that the cost would decrease if we substituted tap water for the distilled water, sugar for sucrose, and glass jar for Erlenmeyer flask. And it wouldn't affect the bud multiplication and shoot growth.1/2MS was the best rooting medium .For BT18, the optimal rooting medium was 1/2MS+IBA0.1mg/L+NAA0.1mg/L, and other clones were all 1/2MS+ IBA0.5mg/L+NAA0.05mg/L. The ex vitro rooting technique of shoot was also studied. The percentage of rooting shoots could reach 93.5 percent if the shoots were soaked in50mg/L NAA solution for 20 minute.The appropriate period for plantlet transplanting is from March to April in spring. Compared with other matrixes, such as soil, vermiculite VS sand (1:1), peat VS pearlite (1:1), vermiculite was the best. Meanwhile, shade and intermittent mist are also necessary.Based on a series of scientific theories and assumptions, the ratio ofmultiplication was estimated and the formula for calculating plantlets yield was figured out. The result of calculation by formula indicated that 88 thousand plantlets and 40 thousand marketable plantlets could be produced yearly for...
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