Effects Of Low Concentration NaCl On The Growth Of Zea Mays L. And Triticum Aestvum L.

Seedlings of Zea mays L.and Triticum aestivum L. growing in Hoagland nutrient solutions were treated with different low concentrations of NaCl. Then the changes in fresh weight ,dry weight; the content of ion, amino acid, soluble sugar, protein, MDA, chlorophyll; membrane permeability, osmotic potential; the activities of SOD, CAT, MDH, PEPCase,RuBPCase and NR were determined. The purpose of the experiment was to see the changes in growth and physiology between the two species under low NaCl concentrations. Furthermore, the mechanism of low NaCl on the growth of the two species was investigated,too. The main results of the experiment are as follows:1. Effects of Low NaCl on the Growth of Zea mays L.and Triticum aestivum L.Both fresh weight and dry weight of whole plant of the two species were higher than the control under low NaCl concentrations, and the largest biomass of Zea mays L. was at 5mM NaCl, and Triticum aestivum L. was at 2.5mM NaCl. With the increase in salinity, both fresh weight and dry weight decreased respectively.2. Effects of Low NaCl on the content of inorganic ions of Zea mays L.and Triticum aestivum L.The content of Na+ and Cl" in shoots and roots of the two species increased with the increase of NaCl concentration in the external medium. In Zea mays L., the content of Na+ and Cl" in roots were higher than that in shoots. In Triticum aestivum L., the distribution of Na+ and Cl" was the same as that in Zea mays L.. Notably, the absorption of K+ was stimulated under low NaCl oncentration in both species.3. Effects of Low NaCl on the membrane lipid superoxidation of the two speciesMembrane permeability of Zea mays L. and Triticum aestivum L. were lower than the controls under low NaCl concentration, and the content of MDA were lower than the controls, too. Besides, reactive oxygen scavenging enzymes such as SOD.CAT, were stimulated by low NaCl. On the one hand, it may be related to the decrease of the amount of ROS , on the other hand , the activities of reactive oxygen scavenging enzymes were enhanced under low NaCl concentration . Owing to these, the membrane lipid superoxidation was very low.4. Effects of Low NaCl on the photosynthesis rate of the two speciesThe photosynthesis rate of the two species were higher than that of the the control under low salt concentration. The photosynthesis rate of Zea mays L. was highest under 5 mM NaCl treatments, but the intracellular COi was lower than that of the control. Furthermore, there was no difference in stomatal conductance under differentNaCl concentration. The data shows that the increase in photosynthesis rate was independent of stomatal factors . Besides, the activities of PEPCase and MDH were enhanced under low salt, which means that the photosynthesis rate was related to the ability of CO2 fixation in mesophyll chloroplast.The photosynthesis rate of Triticum aestivum L. was highest when the medium NaCl concentration was at 2.5mmol/L and it was consistent with intracellular COjand stomatal conductance. The data shows that the changes in photosynthesis may be related to stomatal factors. 5. Effects of Low NaCl on the activity of NR and the content of organic matterUnder low NaCl concentration, the activity of NR in leaves of Zea mays L. and Triticum aestivum L.has increased. So the ability of nitrogen metablism was enhanced by low NaCl concentration. And that, the content of dissociative amino acid were lower than that of the control in both species. On the contrary, the soluble proteins increased under low NaCl medium. At the same time, the content of soluble sugars were lower than that of control in Zea mays L. and Triticum aestivum L., which means a easier process in carbon conversion was conducted under low NaCl . 6.The examination of ion subcellular location status by X-ray microanalysis under low NaClThe content of Na in vacuole .cytoplasm and chloroplast were measured by X-ray microanalysis. There was no significant difference in Na content among the sub-cellular areas under low NaCl treatment. The Na content in chlo...