| Dendrobium officinale in vitro and stems were taken as the test material and lightemitting diodes(LED)as sources of light.The group with white light was taken as control group,and five variates were made in the five experimental groups.They were,blue,red: blue(R:B)=7:1,red: blue(R:B)= 3:1,red: blue(R:B)= 2:1,respectively treating the inducement,proliferation and differentiation of D.officinale PLBs and the effective ingredients of PLBs.Conclusions were drawn as follows:1.Light quality had a significant effect on the inducement,proliferation and,differentiation of D.officinale PLBs.Under blue light and the light of R:B= 2: 1,the inducement rates were 65.67% and 65.47% respectively;under mixed light,with the decrease of the proportion of blue light,the inducement rate gradually decreased;under red light,the inducement rate was 40.15%,which was the lowest.The highest proliferation coefficient was 4.767,which was obtained under the circumstances of R:B=3:1,representing a obviously higher rate than that of other situations.And the PLBs was dark green in color and grew well.Under blue light,the proliferation coefficient of PLBs was 2.208,which was the lowest.And the PLBs was light green in color and grew poorly.The mixed light of R:B=2:1 was conducive to the differentiation of PLBs,and the average number of regeneration buds of PLBs was 9.24,which was two times as many as those under red light.The highest ratio of dry-and-wet weight-0.106 was gained on the condition of R:B=7:1.Therefore,blue light or mixed light of R:B=2:1 can be employed in the period of inducement;mixed light of R:B=3:1 in the period of proliferation;and mixed light of R:B=2:1 in the period of differentiation.2.Light quality had a significant effect on the growth of D.officinale in vitro.The highest root length and plant height were 79.57 mm and 51.47 mm under red light.The largest stem diameter of seedlings in vitro(3.29mm)was obtained under blue light.The highest ratio of dry-and-wet weight-0.121 was obtained under the mixed light of R:B=7:1,followed by the ratio of dry-and-wet weight of seedlings under red light.As the proportion of red light decreased,the ratio of dry-and-wet weight reduced gradually,being the lowest under blue light,that is,0.101.Conclusions can be drawn from the growing status under different treatments of light quality,the seedlings in vitro were in the best situation of growing under the mixed light of R:B=3:1.3.Light quality had a significant effect on the physiological property of D.officinale in vitro.Chlorophyll Content under mixed light of R:B=2:1 and 3:1 was 1.34 mg·g-1FW and 1.26 mg·g-1FW,representing a higher content than other treatments;Superoxide dismutase(SOD),perpxide enzyme(POD)activity and proline(Pro)content were the highest when the seedlings were cultivated under mixed light of R:B=3:1.The number was 366.04 U·g-1FW,13.39 U·g-1FW and 328.29μg·g-1FW respectively.Superoxide dismutase(SOD)activity of seedlings under red light were the lowest(250.44 U·g-1FW).The activity of perpxide enzyme(POD)were the lowest under red or blue light.The Catalase(CAT)activity did not quite differ in different proportion of mixed red and blue light treatments,but it was significantly higher than that under single light treatment.Under different proportion of red and blue light,CAT activity reached the highest under the light of R:B=3:1,which was 18.53 U·g-1FW.Synthesizing the growing status and physiological index,we can conclude that the light treatment of R:B=3:1 is more conducive to the growth of seedlings in vitro.4.Light quality had a significant effect on the main effective ingredients of D.officinale in vitro.The content of Dendrobium polysaccharides in PLBs was the highest under red light,the rate being 16.52%.The lowest content of Dendrobium polysaccharides in PLBs was 8.52%.On the contrary,the content of dendrobine under blue light was higher than any other treatment,with a rate of 0.041% in D.officinale PLBs,which was much higher than the rate of 0.021% under red light.On the contrary,the content of Dendrobium polysaccharides was 27.04% in D.officinale stems,representing a rate obviously higher than that of other light treatments.The content of Dendrobium polysaccharides in stems was 14.36% under blue light,the lowest in this experiment,the content of Dendrobium polysaccharides in stems under red light was almost two time as much as that under blue light.In contrast,the content of dendrobine in stems under red light was 0.033%,the highest content in the experiment,and that under blue light was 0.018%,being the lowest of the research.According to the content of Dendrobium polysaccharides and dendrobine of different parts of seedlings under different light quality,the content of Dendrobium polysaccharides and dendrobine of D.officinale stems was relatively higher. |
