A study on photosynthesis and photo-response characteristics of three Salvia species

To provide basic data for wild plant resources protection and cultivation of three Salvia species,the photosynthetic characteristics of adaptation and physiological response are reported in this paper.Plant chlorophyll concentrations were determined by colorimetry.Photosynthesis characteristics were evaluated using a LI-6400 portable photosynthetic system and data were fitted with different models to investigate the photosynthesis-light response curves using SPSS 18.0.Chlorophyll contents of the three Salvia species were significantly different.Photosynthesis-light response curves of all 3 plants fitted the new photosynthetic light-response model.The apparent quantum efficiency(AQY),Pnmax and LCP of S.miltiorrhiza were 0.040 3,13.32 μmol/(m2·s) and 24.37 μmol/(m2·s),respectively,and were the lowest of the three plants while those of S.paohsingensis were the highest.The light radiation net photosynthetic rate(Pn),intercellular CO2 concentration(Ci),stomatal conductance(Gs) and transpiration rate(Tr) of the three species of Salvia showed different responses to the photosynthetically available radiation flux density(PAR).The new photosynthetic light-response model gave accurate values for the physiological parameters of S.miltiorrhiza,S.paohsingensis and S.brevilabra.Neither S.miltiorrhiza nor S.paohsingensis were typical positive plants,and the shadow resistance of S.brevilabra was good.Intercropping with tall crops such as corn was good for increasing the net photosynthesis rate of S.miltiorrhiza and for retarding transpiration.