Separate and Combined Response to UV-B Radiation and Jasmonic Acid on Photosynthesis and Growth Characteristics of Scutellaria baicalensis.

The negative effects of enhanced ultraviolet-B (UV-B) on plant growth and development have been reported with many species. Considering the ability of jasmonic acid (JA) to improve plant stress tolerance, the hypothesis that JA pretreatment could alleviate the adverse effects of UV-B on S. baicalensis was tested in this study with photosynthesis and growth characteristics. The results showed that UV-B or JA alone both induced photosynthesis inhibition and decreased biomass in stems and leaves. However, the photosynthetic reduction caused by increased UV-B was mainly related to the effect of nonstomatal-limitation, while that of JA was a stomatal-limitation effect. JA pretreatment prior to UV-B could remit the photosynthetic inhibition via the recovery of chlorophyll content, stomatal conductance; and intercellular CO2 concentration (especially the maximum electron transport rate increase). Furthermore, the coaction of JA and enhanced UV-B alleviated some disadvantageous effects on the leaf and did not aggravate the growth damage induced by their separate actions.

[FTIR analysis of the effects of enhanced ultraviolet-B (UV-B) radiation on chemical composition of different parts of Scutellaria baicalensis Georgi].

The effects of enhanced ultraviolet-B (UV-B) radiation on chemical compositions of radix, stem and leaf of Scutellaria baicalensis Georgi were studied via FTIR Results showed that alcohols and phenolic substances in the radix and leaf of S. baicalensis Georgi were increased by UV-B radiation as well as the content of flavonoids and flavonoids glycosides. The terpenoids content in radix and protein content in leaf were increased by supplementary UV-B radiation. Contrary to the circumstance in radix and leaf, contents of alcohols and phenolic, flavonoids, unsaturated fat and lactone in stem were decreased by UV-B radiation. These results indicated that there is a trade-off in distribution of the metabolites in radix, stem and leaf of different parts. More information could be revealed for the result of FTIR spectral analysis via FTIR second derivative spectrum, especially the information of the combination between flavonoids and glycosides. The effects of UV-B radiation on chemical composition in radix, stem and leaf of S. baicalensis Georgi could be examined simply and rapidly via the method of FTIR. Thus, it can be used as a prior method before the further analysis of chemical composition.