Effects of Hormone Factors on the in vitro Culture Flowering Induction of Dendrobium officinate Kimura et Migo

[Objective]The aim was to select the suitable hormone factors for flowering induction in vitro culture of Dendrobium officinate Kimura et Migo.[Method]The test-tube plantlets from the stems of Dendrobium officinate Kimura et Migo were used as the experimental materials and MS medium as the basic medium.Comparative tests have been done between single-factor hormone treatments（different concentrations of PP333 or TDZ） and multi-factor hormone treatments（different combinations of PP333,TDZ,6-BA and NAA） to research the effects of hormone factors on the flowering induction of the plantlets.[Result]Among the single-factor hormone treatments,the suitable concentration and the rate of flower buds formation of PP333 treatment were 0.2 mg/L and 8.5%,the that of TDZ treatment were 0.06 mg/L and 15.5%;the effects of multi-factor hormone treatments on the flowering induction were ordered as follow：（PP333 ＋ 6-BA ＋ NAA ＋ TDZ）〉 （PP333 ＋ 6-BA ＋ NAA）〉 （PP333 ＋ 6-BA） and（PP333 ＋ NAA） ;the most suitable treatment was PP333 0.3 mg/L ＋ 6-BA 0.5 mg/L ＋ NAA 0.5 mg/L ＋ TDZ 0.06 mg/L,the rate of flower bud formation and the rate of the blossomed flower were respectly reached to 80.4% and 90.3%.[Conclusion]PP333 and TDZ showed the important effect on the flowering induction in vitro culture of Dendrobium officinate Kimura et Migo.The effect of TDZ was better than that of PP333.It is much more conducive to the flower bud formation,when using appropriate concentration of TDZ combined with other hormones properly.

Evaluation of Cold Tolerance of Different Dendrobium Species in North China

T o investigate cold tolerance of different cultivars and species in Dendrobium Sw. in North China, 8 strains of Dendrobium officinal and other 5 Dendrobium species were used to compare their cold-hardiness index in this study. The content of electrolyte leakage was increasing in Dendrobium Sw. as the temperature decreasing, while the content of peroxidase(POD) activity and the soluble sugar showed a rising trend before a downward trend. Besides, external morphology was another evaluation standard of cold tolerance. Thus, there was a significant difference between Dendrobium officinal and other Dendrobium species in the cold tolerance, and their cold tolerance capacity was as follows: s1 > s100 >s13 > 1301 > s300 > Dendrobium nobile > s126 > s145 > s95 > Dendrobium lindleyi > Dendrobium chrysotoxum > Dendrobium thyrsiflorum > Dendrobium lohohense.