Responses Of Physiological-biochemical-characteristic Of Spartina Alterniflora To Nacl Stress

This study was carried out to investigate the effect of NaCl stress on growth, the membrane lipid peroxidation, membrane permeability, chlorophyll content, photosynthetic rate(Pn),transpiration rate(Tr),stomatal conductance (Gs),carbon dioxide between cells (Ci), water use efficient(WUE),Vpdl A-PAR, A-Ci,dark respiratory rate, roots activities, specific leaf area(SLA) and leaf dry matter content(LDMC) of Spartina alterniflora, meanwhile it's response to instant CO2 concentration changes, as well as it's photosynthesis , transpiration and other physiological characteristics were deterred. The major results are summarized as follows:1. When NaCl concentration is higher than 500mmol/L, the height of S. alterniflora was inhibited fiercely, height could take as NaCl stress symptoms; however, leaf length and diameter is no significant difference, so they can't be symptoms under NaCl stress. Chlorophyll content is inhibited fiercely (P<0.05). Chlorophyll content was declined and membrane permeability was increased when NaCl concentration higher than 300mmol/L. Height and leaf length is inhibited fiercely (P<0.05) also, so they can be taken as symptom under NaCl stress.2. Low NaCl concentration can lead to membrane lipid peroxidation. Lower NaCl concentration could decrease the MDA and peroxide content by some protection mechanism. When NaCl concentration is higher than 300mmol/L, NaCl stress can lead to membrane lipid peroxidation fiercely, destroy the protection mechanism and increase the MDA content in the leaves; but the MDA content decreases a little in the roots.3. SOD, CAT and MDA have the same change trend on the basic, it can conclude first increase then decline, and they are positive correlation with NaCl concentration. The protection enzyme has a decline trend when NaCl concentration higher than 500mmol/L.POD has a high value when treated with nothing (CK), and has a peak value when NaCl concentration is 300mmol/L.After that, POD declined fiercely in the leaves cells, however it is not significant in the roots cells.4. Photosynthesis and transpiration rate all changed under NaCl stress. Photosynthesis,transpiration rate and stomatal conductance get their max value when NaCl concentration is 300mmol/L, then decrease as the NaCl concentration getting higher; but WUE keep on a relative high level under the stress, meanwhile NaCl concentration has a small effect on Ci .5. Pn-PAR and A-Ci curves were all changed under NaCl stress. The curves were all declined significantly, so we could inferred that higher NaCl concentration inhibited the curves fiercely. These results could demonstrate by the lower apparent quantum yield and higher light compensate point in the A-PAR curve, as well as lower Vcmax and Jmax.6. Different concentration of NaCl and CO2 affects dark respiraation rate of Spartina alterniflora also, under relative high CO2 concentration, NaCl concentration has a slight influnce on Rd of Spartina alterniflora, so plant just has a low consumption of photosynthesis product. Macro analysis indicates that salt concentration can lead to a high Rd. Meanwhile, high salt concentration could fiercely inhibit the max light quantum of light systemâ…¡.