[Comparative Study on Photosynthetic Characteristics and Medicinal Ingredients in Different Months of Inula nervosa]

To compare the photosynthetic characteristics and medicinal ingredients in different months in order to provide a theoretical basis for cultivation and harvest of Inula nervosa.

The photosynthetic characteristics was measured by using LI-6400 and morphological characteristics were compared in different months, and the contents of total flavonoids and total phenols were determined by UV spectrophotometry.

Net photosynthetic rate of Inula nervosa was the highest in June, which showed a single peak curve, and the average of daily change reached to 8.50 μmol/(m2 x s). Light response curve data showed the ability of using the strongest light was in June. Chlorophyll fluorescence parameters values also displayed that, openness of reflect center and photochemical efficiency of leaves' photosystem II were the highest, which also had the fastest rate of electron transfer in June. Morphological indicators showed that the single leaf area and leaf area of Inula nervosa were significantly higher in June than those in other months. The content of total phenols were much higher than that of total flavonoids in Inula nervosa. And the medicinal ingredient content of the underground part was higher than that in the aerial part.

The best harvest time of underground part of Inula nervosa should be after autumn, when the weight and active ingredients are accumulated to a considerable level.