| The Oriental hybrid 'Siberia' is used for experimental materials.The effects of explants,hormones, medium and culture conditions on the development of bulblets in vitro were investigated;the mechanism of dormancy of bulblets in vitro and the factors influencing dormancy were investigated.The results are as follows:1.The large scale explants regenerated larger bulblets than small explants did,and also the weight per bulblet.Scales can be cut to generate more bulblets,cutting the scale into half from middle longitudinal side the number of bulblets up to 6.4,significantly more than other cutting methods.Scale orientation in medium had no significant impacts on the quantity,weight,diameter of the bulblets,while significant impacts on the shape of bulblets.There were more abnormal bulblets when scale ventral down or vertical insertion,the bulblets generated from medium surface and seemed to closer normal shape when scale ventral down.Both endogenous ABA and exogenous ABA can inhibite the formation of scal-leaves.In the light(30μmol.m-2.s-1)16h and dark 8h conditions,nearly one scal-leave developed per bulblet.In the dark,there were nearly no bulblets formed when no sucrose existed in medium,the number of bulblets was most in 30g·L-1 sucros and it would reduce as the concentration of sucrose increased. The weight per bulblet was higher in 90g·L-1 and 120g·L-1 sucrose,but the number of abnormal bulblets increased either.The bulblets generated in 30g·L-1 and 60g·L-1 were normal,and the 60g·L-1 sucros was most suitable for bulblets generation.In the light(30μmol.m-2.s-1)16h and dark 8h condition,the number of bulblets was most in 30g·L-1 sucrose also,the weight per bulblet was highest in 90g·L-1 and the shape of bulblets wase also normal.As the concentration of sucrose increased,the number of scal-leaves increased,and the relative weight of bulblets decreased.When the concentration of sucrose was 90g·L-1, there were no scal-leaves generated.In different temperature cultivations the weight and diameter per bulblet existed significant differences,the sequence was:25℃＞20℃＞15℃＞30℃,25℃was most suitable for 'Siberia'.When the temperature was either too heigh(30℃) or too low(15℃),the bulblets formation would be inhabited.When bulblets were excised from the explant and cultured onto the same medium growth continued,it showed that the presence of scale explant was not necessary.2.Fluridone can reduce the level of dormancy,and the function can be reversed while adding exogenous ABA.It suggested that the exogenous ABA can promote the development of dormancy.The dormancy level of bulblets in vitro cultured at 15℃,20℃,25℃would raise with the temperature,and the low concentration of exogenous ABA(0.1 mg.l-1) had no effects on the dormancy level of bulblets at 15℃,20℃,25℃.3.Both the sprouting rate of bulblets in soil and the speed of germination would increase during low temperature storage.The sprouting rate reached to 100%and dormancy broken compeletly after 9 weeks during 5℃storage.There were some relations between level of dormancy and microstructure of shoot-top.When the shoot-tip cells got to active mitosis from interphase stimulated by low temperature, the dormancy would release gradually.The content of starch decreased and content of sucrose increased during low temperature storage.Larger bulblets developed much faster than small ones and there were some relations between the rate of bulblets with stem in soil and the weight bulebles in vitro,when the weight of bulblets less than 1100mg,no bulblets sprouted with stem,when the weight of bulblets more than 1100mg,the larger bulblets sprouted with stem much more easily.
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