Study on the Propagation of Nobile-Type Dendrobium and Flower Induction of the Orchids in Vitro

Title Study on the Propagation of Nobile-Type Dendrobium and Flower Induction of the Orchids in Vitro
Abstract

The Nobile-type Dendrobium, plays an important role in orchid industry, and was mainly propagated in cutting and high layering. But the propagation coefficient of the ways was quite low and reproductive cycle was very long. Recently, the Nobile-type Dendrobium has a large-sale volume in foreign market, but was only used as potted flower in China. Moreover, the better varieties were introduced from Japan, which had restricted the further researching and development of the Nobile-type Dendrobium in China. The twenty-three Nobile-type Dendrobium varieties, which were introduced from Japan, were used as test materials in this study. The main researching contents of the lateral bud propagation of the Nobile-type Dendrobium in vitro as follows: the disinfection scheme of their lateral bud explants, the effect of the different hormone on the lateral bud propagation of some varieties and the subculture of their plantlets. Simultaneously, the studies on the in vitro flowering of the D.Spot Right, D.densiflorum and Cymbidium emsifolium (L.)‘XiaoTaoHong’×C.aloifolium (XTW) were implemented. Their experimental results as below:1. The experimental results of the best disinfection scheme and light condition of the Nobile-type Dendrobium showed that the best disinfection scheme of the three representative varieties (004,022 and 052) was that retained one layer leaf sheath outside the lateral bud tip, the 75% ethanol disinfected for fifteen seconds and the 0.1% HgCl2 disinfected for eight minutes. Besides, the dark culture of the lateral bud explant was beneficial to reducing their browning effect.2. The germination rate, proliferation rate and propagation ratio of the Nobile-type Dendrobium were studied under the same culture conditions. The results showed: their differences among the twenty-three varieties were significant, 51.97% of the 483 explants were not suitable for large-scale propagation at factories. Took the propagation ratio as basis and their values (1.0 and 2.0) as criterial, the twenty-three varieties were divided into high, central and low groups. The results of the 6-BA concentration gradient experiments suggested that the very 6-BA concentration suitable for proliferating of the three representative varieties (022,021 and 026) were 3.39, 2.07 and 1.92 mg/L, respectively; these 6-BA concentration could meet the proliferation needs of the members within the group. The medium (1/2 MS+NAA 1.0 mg/L +6-BA 4.0 mg/L+ carrageenan 7.0 g/L+sucrose 20 g/L+coconut milk 100 ml/L+ bacteriological peptone 2.0g/L) was fit for the propagation of the four varieties (001,002, 004 and 022).3. The relationship between the lateral bud propagation ratio of the twelve varieties of the Nobile-type Dendrobium and the concentration of the three kinds cytokinin (6-BA, KT and TDZ) was parabola. The order of the effect on the three kinds of cytokinin for the mean propagation coefficient of the twelve varieties were KT>6-BA>TDZ. Based on the medium (1/2 MS+NAA 1.0 mg/L+carrageenan 7.0 g/L+sucrose 20 g/L+coconut milk 100 ml/L+ bacteriological peptone 2.0g/L), we supplemented 3.0 mg/L 6-BA suitable for the 004 variety propagation, 2.0 mg/L KT fit to the 005 and 035 varieties, and 3.0 mg/L KT for the three varieties, 015,019 and 026.4. The effects of the auxin on the propagation rate of the D.Tubuyaki and D.Shirasagi were significant, and so were the effects of the 6-BA and 6-BA×KT on the D.Tubuyaki and D.Shirasagi. 0.5mg/L NAA+1.0 mg/L 6-BA+0.5 mg/L KT were suitable for the D.Tubuyaki proliferation, and 0.5 mg/L 2,4-D+1.0 mg/L 6-BA+1.0 mg/L KT were for the D.Shirasagi proliferation.5. The subculture conditions of the five Nobile-type Dendrobium varieties were different. 1/2MS+carrageenan 7.0g/L+sucrose 20g/L+coconut milk 100ml/L+ bacteriological peptone 2.0g/L+6-BA3.0 mg/L+NAA0.3 mg/L were suitable for the subculture of the three varieties, 002, 004 and 022. The browning and growth conditions of the plantlets from the lateral bud in D.Casiflake and D.Emur via tissue culture could be improved through adjustment of the basal medium composition. And on the basis of the above media, the browning of D.Casiflake and D.Emur during their subculture could be effectively prevented by supplementing it with 0.03% active carbon.6. The preliminary induction formular of in vitro flowering in orchids was established, which was supplementing with low nitrogen(N) and high phosphrous(P) and variable temperature, on basis of the sucrous 40g/L+carrageenan 6g/L+4.0 mg/L 6-BA. Under variable temperature (18℃±1/25℃±1, night/day), two flower buds of two plants from the D.densiflorum were induced, which opened malformation white flower under the treatment MS1 (1/3N,9P), and two flower buds from a plant of the D.densiflorum were induced, which opened normal yellow flowers under the treatment MS4(1/6N,15P). However, these treatments didn’t have the flower bud inducing effect in the aseptic seedings of XTW and the plantlets of the D.Spot Right in vitro.7. The effect of the mature degree of the plant materials on the in vitro flowering in orchids was studied. The flower bud could be induced from the mature orchid plants under cytokinin(6-BA and TDZ) treatment. On the condition of the medium: 1/2MS+sucrous 40g/L+ carrageenan 8g/L+active carbon1.0g/L, two flower buds of a plant in XTW were induced by supplementing with 6-BA 1.0 mg/L+TDZ 0.1 mg/L, two flower buds of two plants in XTW were induced by supplementing with 6-BA 10 mg/L+TDZ 1.0 mg/L, and 6 flower buds of 6 plants of D.Spot Right were induced by supplementing with 6-BA 5.0 mg/L.

Category Gardening
Keywords difference, in vitro flowering, Nobile Type Dendrobium, Orchid, propagation via tissue culture,
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Pages 104
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