Comparative Studies On Photosynthesis Of Eremurus Altaicus (Pall.) Stev, Eremurus Inderiensis (M. Bieb) Regel And Eremurus Anisopterus (Kar. Et Kir) Regel

Many indexes such as photosynthetic pathway, chlorophyll content, biomass, Pn, E, Gs, Ci and chlorophyll fluorescence characteristics of Eremurus altaicus (Pall.) Stev, Eremurus anisopterus (Kar.et Kir) Regel and Eremurus inderiensis (M.Bieb) Regel were comparatively studied, which wildly grow in Xinjiang. Futhermore, we discussed the unused mechanism of nutriment of E.altaicus, E.inderiensis and E.anisopterus. The main contents include the basic photosynthetic characteristics of Eremurus, the interior and exterior factors affecting the photosynthesis of Eremurus, methods of evaluation on the photosynthesis and technology of chlorophyll fluorescence of Eremurus. The main results showed:1. Under natural condition, the portable photosynthesis system of Li-6400 was used for the dynamic research of photosynthesis of Eremurus altaicus, Eremurus inderiensis and Eremurus anisopterus at seedling and flowering stages, and then we get the diurnal change curves of photosynthesis of every stage and A-light curves. Results indicate that the diurnal changes of net photosynthetic rate of Eremurus inderiensis and Eremurus anisopterus displayed single-peak pattern at seedling stage and two-peak pattern at flowering stage. Both seedling stage and flowering stage, the diurnal changes of net photosynthetic rate of Eremurus altaicus displayed two-peak pattern. The photosynthetic"midday-depression"could be apparent in the three species. The significant difference between A-light curves of the three plants and typical desert plants show that they are all high light saturation point, low light compensation point and strong respiration as C3-C4 intermediate plants, which indict their special way for adaptation to desert habitat.2. Photoinhibition of photosynthesis induced by strong light was related to the inactiveness of PSII reaction center, and xanthophyll cycle played a pivotal role in protecting photosynthetic apparatus. The decline of photosynthesis is due to stomatal limitation. The big CO₂ concentration can increase the Eremurus photosynthesis.3. Stomata controled the carbon–water balance in plants by acting as transport for diffusive CO₂ uptake and water vapor loss. Drought–resistant species should have strong stomata control over gas exchange, stomata maximize the rate of carbon gain while minimizing water loss. Instantaneous control of transpiration flux by stomata often represents an additional constraint to plant productivity. Therefore, poor stomatal control in plants, with leaves continuing to lose water under severe water deficit is inefficient water use types. In our study, we find that Eremurus altaicus use water less efficiently than the other two species of Eremurus .4. During the time of measuring photosynthesis of the three species, the portable chlorophyll fluorescence system of OS5-FL, which is made in USA, were used to measure diurnal changes of chlorophyll fluorescence at the same time. Results show that exposuring the three plants to natural high irradiance induced lowering of photo-chemical quenching (qp), photochemical efficiency of PSII (Fv/Fm), and electron transport rate (ETR) while increasing F0 (minimal ini-tial fluorescence), Yield (Y), and non-photochemical quenching (qN).5. After treated by DTT, Fv/Fm was much lower, but F0 was much higher than those of control. These results indicated that xanthophyll cycle played an important protective role against photo-damage to the photosynthetic apparatus in leaves of the plants during diurnal variation of photosynthetic efficiency.