CO2倍增对霍山石斛光合特性和生长的影响

为评估CO₂倍增对霍山石斛光合特性和生长的影响,本研究以霍山石斛幼苗为试材,比较了CO₂浓度400 μmol/mol（大气浓度,对照组）和800 μmol/mol（处理组）栽培180 d对霍山石斛光合特性、生长和有效成分的影响。结果表明,CO₂倍增处理显著提高了霍山石斛的净光合速率（P_n）、气孔导度（G_s）、蒸腾速率（T_r）和水分利用率（WUE）,但霍山石斛未出现“光合适应”现象。栽培30 d后,处理组的存活率、着根率和新芽数始终显著高于对照组,而60 d后,处理组的叶片可溶性蛋白含量显著低于对照组。栽培180 d后,CO₂倍增处理组显著提高了霍山石斛的茎鲜重、茎干重、茎长、单株叶片数和叶片厚度,而对茎粗和单叶面积无显著影响。同时,处理组也显著提高了茎的多糖含量,比对照组提高94%,但生物碱含量则显著下降。茎的总氨基酸含量与总黄酮含量在两组间无显著差异。综上,CO₂倍增处理能显著促进霍山石斛的生长,提高成活率及其主要药用部位茎的产量和多糖含量。

Effects of Doubled Atmospheric CO2 Concentration on Photosynthetic Characteristics and Growth of Dendrobium huoshanense

In order to investigate the effects of doubled atmospheric CO₂ concentration on the photosynthetic characteristics and growth of Dendrobium huoshanense, the photosynthetic characteristics, vegetative growth and contents of effective constituents of D. huoshanense were evaluated using the seedlings after doubled atmospheric CO₂ concentration treatment (800 μmol/mol, 400 μmol/mol as control) for 180 days. The results showed that the net photosynthetic rate, stomatal conductance, transpiration rate and instantaneous water use efficiency significantly increased in leaves compared with the control. There was not photosynthetic acclimation during the experiment. After cultivation for 30 days, the survival rate, rooting rate and number of new buds of the treatment group were always significantly higher than that of the control group, while the soluble protein content in leaves of the treatment group was significantly lower than that of the control group after 60 days. Stem fresh weight, stem dry weight, stem height, leaf number per plant and leaf thickness also significantly increased in the treatment group, but there was no significant effect on stem thickness and leaf area. Moreover, the polysaccharide content of stems significantly increased in the treatment group, with 94% higher than that in the control group, while the alkaloid content significantly decreased, and there was no significant difference in the contents of total amino acid content and total flavonoids between the two groups. In conclusion, doubled carbon dioxide concentration treatment could significantly promote the growth, increase the survival rate, stem yield and stem polysaccharide content.