目的研究营养因子对铁皮石斛(Dendrobium candidum Wall.Ex Lind1)幼苗生长的影响。方法以铁皮石斛幼苗为外植体,以培养一个周期后的生物量、分蘖数或生根数为指标,采用单因素实验分别考察不同培养基、碳源种类、氮源总浓度及两种形态氮素配比和活性炭添加量5组因子对幼苗生长的影响,对生物量的统计学处理采用单因素方差分析和q检验。结果在幼苗生长过程中,20%马铃薯汁可显著促进植株分蘖形成,1/2MS(大量元素减半)+20%马铃薯汁是铁皮石斛幼苗分蘖和生长的适宜培养基。除乳糖外,30g·L-1蔗糖和葡萄糖均适合幼苗生长,且对其生物量的影响无显著差异。培养基中氮源浓度过高抑制幼苗的生长,氮源以30mmol·L^-1总氮量,NH₄⁺/NO₃^-的比例为0∶3或1∶2较适宜幼苗生长。培养基中3g·L^-1的活性炭可使试管苗每株生根数提高为对照的3.26倍,使干重显著提高(P<0.05),且生长健壮。结论适宜的营养条件可使铁皮石斛幼苗的分蘖增殖培养与生根壮苗培养在同一种培养基上一步完成。

OBJECTIVE To investigate the effects of nutritional factors on the growth of Dendrobium candidum seedlings.METHODS Dendrobium candidum seedlings were used as explants,the single factor design was applied to estimate the effects of various factors including culture medium,carbon source,nitrogen source and active carbon on the growth of Dendrobium candidum seedlings,with its biomass,tiller number or average root number as index.The data of biomass were analyzed with One-way ANOVA and q test.RESULTS As for seedling growth,20% potato juice significantly promoted the tiller formation of the in vitro plantlets,the suitable culture medium for seedling to tiller and growth was 1/2MS(half of macro-elements)supplemented with 20% potato juice.Carbon source test indicated no significant difference in the biomass and growth of seedlings between sucrose and glucose except lactose.Nitrogen source results showed that the suitable nitrogen concentration for the growth was 30 mmol·L^-1.the best ratio of ammonium to nitrate were 0∶3 or 1∶2,while excessive concentration of nitrogen source inhibited seedling growth.The concentration of active carbon added in the medium was 3 g·L^-1,which not only increased significantly the dry weight of this plant(P<0.05)but also made the average number of roots per plantlet increase to 3.26 times comparing with the control,furthermore the plantlets grew healthy and strong.CONCLUSION Tiller propagation,rooting and growth-promoting of Dendrobium candidum seedlings could be carried out in the same medium under suitable nutritional conditions.