The Physiological Mechanism Of Coix Aquatic Roxb Responding To Different Chromium (Ⅵ) Concentration

In this study,1/2hoaglands nutrient solution culture were used with different concentrations of Cr6+ (0.5,1,10,40 mg·L-1),in order to study the physiological mechanism of Coix aquatic Roxb responding to different Cr6+ concentration with the following aspects,such as the purification effect of Cr6+,the effect of Cr6+ on the root physiological indices.the effect of Cr6+ and inhibitors LaCl3, Nif on root exudates, the attribution and position of Cr6+ in the body, as well as provided phytoremediation of chromium pollution of water the basis for the theory and application. Here, the main results of this study are summarized as follows:1.There is a certain effect to wetland plants under different concentration of Cr6+, mainly showed that promoted under low concentrations, and inhibited under high concentration; The treatment effect in different concentration of Cr6+ declined with the experiment time went.Coix can clean the low concentration of Cr6+ well, the removal was stable, and the removal of 1 mg/L Cr6+ was better than 0.5mg/L.In the beginning of this experiment, the revomal of 40mg/L Cr6+ was better than 10mg/L2.Under chromium stress, the net photosynthetic rate, stomatal conductance, transpiration rate at low concentrations (0.5mg/L,1 mg/L Cr6+) is showed promotion when high concentration (1 0mg/L, 40mg/L Cr6+) treatment was restrained, and became significant with the treatment time went, and 0.5mg/L Cr6+ handling role in promoting higher than 1mg/L Cr6+ treatment; intercellular CO? concentration was in contrast with the above three, being increased with increasing concentration, and being reduced with time.3. Under chromium stress, low concentration (0.5mg/L, 1mg/L Cr6+) treatment inhibited root iron plaque number, high concentration (10mg/L,40mg/L Cr6+) but stimulated root iron plaque formation, membrane adsorption of chromium iron iron film with the number of environmental chromium content and the growth of the processing time increase. Root activity in the pilot phase, in addition to 40mg/L Cr6+ treatment decreased, other concentrations were higher than those in control at all times, heavy metals have shown to stimulate the role of root activity. Stress in barley by Cr6+, various concentrations of root membrane permeability is increased, especially 40mg/L treatment, show significant differences. The level of increase as the extension of test time and growth.4. Under the stressof chromium, the trend of citrate exudation generated by roots is also guided by the "promote at low concentration (0.5mg/L, 1mg/L Cr6+) and inhibite at high concentration (10mg/L,40mg/LCr6+) "phenomenon, the secretion increased with the extension of test time, and the secretion under 0.5mg/L Cr6+ treatments greater than 1mg/L Cr6+ treatment. After adding calcium channel blockers did not significantly different, but the added anion channel inhibitors reduced the secretion of citrate.5. Under the stressof chromium, the secretion of amino acids in roots at low concentrations is higher than the control, expressed as a catalytic role in the treatment of high concentration lower than the control, expressed as inhibition. And calcium channel inhibitors and anion channel inhibitors on the secretion volume of amino acids have a greater impact.6. Under chromium stress, low concentration (0.5mg/L, lmg/L Cr6+) in root exudates when the soluble sugar content variation with time is not strong, with the regularity of concentration is not strong, but high concentration (10mg/L,40mg/L Cr6+) showed inhibitory effect, and when it had seldom significant change with the addition of calcium channel blockers, but it showed a catalytic role the added anion channel inhibitor.7,Under chromium stress, Coix roots, stems and leaves as the chromium content within the extension of test time increases, and with the increasing concentration showed a significant increasing trend, the performance of the cell wall of root (including the intercellular spaces) is greater than the vacuole, organelles, cell wall (including the intercellular spaces) and the vacuole is much higher than the chromium content in the vacuole in the item, leaf showed higher content of low concentrations, high concentration of organelles more content phenomenon. The oxalate substances of chromium in root was not detected under low concentration, they mainly were alcohol-soluble chromium proteins, amino acids and salt-based water-soluble organic acid-based substances in item, and the chrome was mainly existed pectate, and protein bound chromium and heavy metals insoluble in water and other forms of phosphate present in leaf.8. Under transmission electron microscope, heavy metal existed in radicle, caulicle, young leaves was mainly in the cell wall and cell space, the vacuole was also presented a small amount of chromium.