Morphological And Physiological Responses Of Chenopodium Album L. To Salt Stress

Chenopodium album, belonging to genus Chenopodium, widely distributes all over the world. It is meaningful to investigate comprehensive responses to NaCl stress at different levels in Chenopodium so as to make a better understanding of the salt-tolerance mechanisms of the salt-tolerant species. The present study focused on the morphological, physiological changes in C. album under short- and long-term stress of different salt concentrations, by using paraffin sections, SEM, stereomicroscope methods, and measurement of various physiological parameters. The key results are as follows:1. Under short-term salt stress, the contents of relative water, electrolyte, MDA and betaine were not significantly affected under different concentrations of NaCl. However, the contents of soluble sugar and free proline were increased with the increasing of salinity. The results showed that there was no significant difference of various parameters between low and high salt concentrations treatments. The growth and development of plant were not affected over a short period of NaCl stress.2. After a long-term of salt stress, the height of plant and diameter of stem decreased with the increasing salinity. The leaf area and anatomic structure were not affected, while the thickness of meristem and medulla in stem anatomic structure were increased; in root, the trachea density was reduced while lignification was strengthened. Furthermore, large number of salt bladders were observed on leaves, the number of which seemed not to increase with the increasing salinity. Crystals were observed in leaf and stem cells. The results indicated that during a long-term salt stress, the morphological structure of C. album was changed in some extent.3. During a long-term salt stress, the chlorophyll and relative water content of C. album were decreased more significantly in anthesis than at seedling stages. Marked increments were observed in relative electric conductance, proline and betaine contents at both seedling and anthesis stages. The content of soluble sugar was notably elevated during seedling stage, but decreased to the control level at anthesis stage. The content of MDA was not affected at both anthesis and seedling stages. The results suggested that during a long-term salt stress, C. album adjusted itself at physiological level to adapt the stress.By analysis of the responses of C. album to short- and long-term salt stress on the morphological and physiological levels, suggesting that the physiological parameters were not significantly changed except for soluble sugar with which an increment was observed under short-term salt stress; while exposed to long period NaCl stress, significant changes were observed in both structural and physiological levels. Although the growth of C. album was suppressed under long term of high salt stress, C. album could adjust itself at both morphological and physiological levels to adapt the stress, and completed the life cycle. Taking together, it imply that C. album is a salt-tolerant species, and such salt-resistant property was attributed, at least partially, to the changes in structure and the adjustment at physiological levels.