太空诱变对金钗石斛光合特性和生长的影响

Effects of Space Mutation on Photosynthetic Characteristics and Growth of Dendrobium nobile

摘要:

为了解太空诱变对金钗石斛（Dendrobium nobile）生长发育的影响，对太空诱变和野生金钗石斛的叶片结构、光合特性和生长指标进行了比较研究。结果表明，太空诱变后的金钗石斛叶片较厚，叶气孔密度大、气孔器长轴和短轴长度均变长。两种金钗石斛的光合速率日变化趋势相似，均为双峰型曲线，但太空诱变的净光合速率低于野生的。太空诱变和野生金钗石斛最大净光合速率分别为4.6和6.8 μmol m^-2s^-1，光补偿点分别为18.3和12.6 μmol m^-2s^-1，光饱和点分别为1180和720 μmol m^-2s^-1。太空诱变和野生金钗石斛的CO₂补偿点分别为100和102 μmol mol^-1，CO₂饱和点分别为2215和2090 μmol mol^-1。太空诱变的金钗石斛单茎鲜重和干重均低于野生种，但由于其分蘖数增加，每盆的总生物量反而增加；太空诱变的金钗石斛生物碱和石斛多糖含量显著高于野生种。因此，太空诱变为金钗石斛育种和品质改良提供了新途径。

Abstract:

In order to understand the effects of space mutation on development of Dendrobium nobile, the leaf structure, photosynthetic characteristics and growth index between space mutation and wild type were compared. The results showed that there were thick leaf, dense stoma, and big stomatal apparatus in space mutation D. nobile. Diurnal variation of net photosynthetic rate (Pn) of the two kinds of D. nobile showed a similar bimodal curve. However, Pn of space mutation D. nobile was lower than that of wide type. The maximum photosynthetic rates of space mutation and wild D. nobile were 4.6 and 6.8 μmol m^-2s^-1, light compensation rates (LCP) were 18.3 and 12.6 μmol m^-2s^-1, light saturation points (LSP) were 1180 and 720 μmol m^-2s^-1, CO₂ compensation points (CCP) were 100 and 102 μmol mol^-1, CO₂ saturation points (CSP) were 2215 and 2090 μmol mol^-1, respectively. Fresh weight (FW) and dry weight (DW) per shoot of space mutation D. nobile was lower than that of wide type. However, due to the increment of tiller number, total biomass per pot in the space mutation D. nobile was more than that of the wild type. Additionally, the total alkaloid and polysaccharide contents in space mutation D. nobile was significantly higher than those of wide type. So, space mutation would provide a new way for breeding and quality improvement of D. nobile.