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The Effects Of Four Salt Stresses On The Solute Accumulation In The Shoots Of An Alkali-resistant Hapophyte K.sieversiana

Posted on:2008-05-13Degree:MasterType:Thesis
Country:ChinaCandidate:D W ZhangFull Text:PDF
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Kochia sieversiana, a naturally alkali-resistant halophyte, was chosen as the experimental plant species for this research. According to the salt components of salt-alkalinized soil in the northeast of China, four kinds of salt stresses, NaCl, Na2SO4, NaHCO3 and Na2CO3, were set up. According to the tolerability of K. sieversiana to the four kinds of salt stresses, we designed different concentration ranges for each stress group, which were 0~1000mM for NaCl, 0~800mM for Na2SO4, 0~600mM for NaHCO3, and 0~175 mM for Na2CO3. By determining the accumulations of inorganic ions such as K+ and Na+ and organic solute such as proline, the differences of the effects of the four salt stresses on the solute accumulation in K. sieversiana shoots were analyzed and compared, then the traits of various anions (Cl-, SO42-, HCO3-, and CO32-) stressing on K.sieversiana and the physiological responses of K. sieversiana to these stresses were further explored. The main results and conclusions from the experiment were showed as follows:1. The tolerabilities of K. sieversiana to various salt stresses are dissimilar. The highest treatment concentrations of that K. sieversiana can tolerate to Na2CO3, NaHCO3, NaCl and Na2SO4, are 175 mM, 600mM, 1000mM, and 800mM respectively. It is obvious that the stress intensities of the four salts to plant are very different. Under the same Na+ concentration, the order of stress intensity from strongth to weakness is Na2CO3 >NaHCO3 >NaCl >Na2SO4. The stress intensity of alkaline salt is stronger than that of neutral salt; CO32- is stronger than HCO3-; Cl- is stronger than SO42-.2. The physiological responses of solute accumulations in K. sieversiana shoots to four salt stresses have shown their similarities not only, but also shown their respective traits. Under four salt stresses, the contents of Na+, SO42-, K+, proline, betaine, and organic acid all increased with increasing the concentration of stress salts. But the contents of K+, Ca2+, and Mg2+ showed a tendency that decreased first and then increased rapidly with increasing of the concentration of stress salts.Under the same Na+ concentration, the increasing extents of Cl-, Na+, and proline and the decreasing extent of K+ in the seedlings stressed by NaCl were greater than that by Na2SO4. However, under stronger stress (generally over 400 mM of Na+ concentration), the contents of betaine and organic acid accumulated caused by NaCl stress were lower than that by Na2SO4 stress. The increasing extents of divalent cations, Ca2+ and Mg2+, under NaCl stress were slightly higher than that under Na2SO4 stress. The SO42- as the anion of Na2SO4 stress, its content was higher in Na2SO4 stress group than that in NaCl stress group.Under NaHCO3 stress, the content of Na+, organic acid, proline, and betaine all increased with increasing the concentration of NaHCO3; the decreasing extent of K+ was similar with that under NaCl stress; whereas the increasing extents of divalent cations, Ca2+ and Mg2+ were greater than that under NaCl stress.Under Na2CO3 stress, the eight strain indexes, Na+, organic acid, proline, betaine, SO42-, K+ , Ca2+, and Mg2+,all increase sharply, and their increasing extent is obviously greater than other stress groups. It indicates that there are differences among the actions of various salt stresses on K. sieversiana not only, also among the responses of K. sieversiana to these stresses.3. Under the four salt stresses, the mechanisms of osmotic adjustment in the shoots of K. sieversiana are similar. Their shared essential features were that organic acid and inorganic ions accumulated largely in the vacuoles, and betaine as an organic osmolyte accumulated largely in cytoplasm.4. Under the four salt stresses, the characteristics of ion balance, especially the sources of anions, in the shoots of K. sieversiana are different. Cl- is main anion for NaCl stress, but the contribution of organic acid to anion is more significant for Na2SO4, NaHCO3, and Na2CO3 stresses.
Keywords/Search Tags:Kochia sieversiana, salt stress, inorganic ions, organic osmolyte
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