Studies On Exogenous Silicon On Glycyrrhiza Uralensis Physiological Mechanismunder NaCl Stress

Salt stress is one of the key factors that limit the artificial cultivation of Glycyrrhiza in the northern region. How to alleviate the damage of NaCl stress on the growth of Glycyrrhiza and to stabilize and improve the yield and quality of glycyrrhiza has become an urgent problem to be solved. Using Glycyrrhiza uralensis Fisch as a research material, five salt treatments were designed in this paper to study the effects of different concentrations of Si on the yield, quality, physiology indexes of stress resistance, carbon and nitrogen metabolism, and contents of K+, Na+, and Si of glycyrrhiza by pot experiment. Multi-level comparative analysis was taken to define the influence mechanism of Si on glycyrrhiza growth under NaCl stress and to seek the compositive optimal Si concentration for the growth and development of glycyrrhiza under different salt concentrations, providing an important theoretical basis for the cultivation of high-yielding and high-quality glycyrrhiza in saline environment. The main results of experiment were as followed:1、NaCl Stress lead to the growth retardation of licorice’s growth on aerial part and roots,which Caused by the yield and quality decrease. Application of silicon can significantly increased the plant height, root length, stem diameter, branch number and lateral root number of licorice,also significantly increased the biomass,increase the tree number under theNaCl Stress.In different NaCl Stress, the influence of those index under exogenous silicon different from time and concentration.In all silicon concentration,the maximum of plant height increased 69.32%; stem diameter increased28.63%; root length increased 27.51%; branch number increased 89.09%; lateral root number is increased 2.06 times; root diameter increased 40.74;and biomass can significantly accumulation,the increase of root fresh weight reached 54.57%; root dry weight enhanced 90.06%; stalk fresh weight reached 68.06%;stalk dry weight increased 50.78%; leaves fresh weight reached 2.82 times;leaves dry weight enhanced 79.31%;the tree number ultimate increased 48.48%.2、Comparied with application of silicon and no silicon treatment,which application of silicon can improve the superoxide dismutase(SOD), peroxidase(POD), catalase(CAT) activity of leaves, licorice can remiss injure of NaCl stress by improving the enzyme activity.In all treatments,the SOD activity increased 42.03% in maximum;the POD activity enhanced 55.29%;the CAT activity increased 74.67%.proline decreased 39.72; the content of soluble protein had increased 88.19%; soluble sugar content increased 99.44%; malondialdehyde(MDA) decrease 42.38%; cytomembrane permeability had increased 43.15%.3、Carbon-Nitrogen Metabolism can reflect the status of dry matter accumulation firstly.and completed the metabolism mainly rely on the enzyme.Application of silicon can significantly increased the activity of sucrose synthase(SS)、sucrose phosphate synthase (SPS)、glutamine synthetase (GS) andnitrate reductase(NR) of licorice under the NaCl stress,also can increased the metabolites content significantly.In different concentration of silicon, ,the maximum of SS activity increased 49.64%; SPS activity increased 54,75%,NR activity increased 50.18%;GS activity increased 163.34%.The content of total sugar increased 25.70%; total nitrogen increased 65.89%.4、On the salt-stress caused by NaCl ,the Na+ is the mainly factor damaged licorice, exogenous silicon significantly reduced the content of Na+, promoted rising the content of K+,also increased K+/Na+ in plants. Silicon make the Na+ content decreased of licorice root,and the highest content is 0.74 times for comparison(not adding silicon); the Na+ content of stalk is 0.56 times,the highest content of K+ at the foot is1.16 times for comparison,at stalk increased 60,17%; K+/Na+ in root had increased 64.35%,in stalk increased 100.57% and increased 109.94% la leaves.silicon can promote uptake K+ and inhibit the absorption of Na+, which may he one of the main mechanisms that silicon reduce salt damage of plants,5、Exogenous sillicon alleviates salt-stress caused by NaCl of licorice,and it is the most important factor of the silicon content la conclusion, the highest content of silicon on root is 2.20 times far comparison(not adding silicon), it was 2.38 times on stalk and 2.09 times on leaves, also there would have the correlation of silicon between K+ and Na+,the content of K+ and Na+ have effect on the accumulation of rnetabolites.Thus, adding the silicon can improve the physiological property of licorice under the salt stress. Eventually, the salt stress and the harm would reduced.So,it would promote the licorice to growth under the salt stress, increase the salt-resistant of licorice.