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Northwest University for Nationalities (2017)

The Physiological Mechanism of Stronger Salt Tolerance of Tall Fescue Cause by Silicon Application

宋锐;

Titre : The Physiological Mechanism of Stronger Salt Tolerance of Tall Fescue Cause by Silicon Application

Auteur : 宋锐;

Grade : Master’s Theses 2017

Université : Northwest University for Nationalities

Résumé
Tall fescue is characterized by development of fibrous root,rapid growth,strong regeneration capacity,and strong resistance to heat,salt,cold,drought and disease.It is the main grass species of artificial grassland and lawn green land in arid and semi-arid area of northern of China.Irrigation is one of the principal measures to maintain high yield pasture and healthy lawn green land.However,long-term irrigation has usually resulted in the secondary salinization and affected the healthy pasture.Therefore,improving tolerance ability to salt of artificial grassland and lawn green land is an urgently scientific issue in the pasture management.Previous studies indicated that addition of silicon significantly improves the tolerance of plants.But its physiological and ecological mechanisms are still well-know.Accordingly,In the study is combined water culture and pot experiment,effect of silicon application to emergence,growth of aboveground and underground,photosynthesis,antioxidant system,adjusting osmotic substance concentration and peroxidation of tall fescue under the different salinization conditions.Disclosing the physiological mechanism of stronger salt tolerance of tall fescue cause by silicon application,and main conclusions are drawn as following.Firstly,addition of silicon encourager the emergence and increased the aboveground growth of tall feasure under the different salt conditionsWith the increasing of salt concentration,the germination,biomass,height,leaf number and tiller of tall fescue decreased.Silicon application significantly increased germination,biomass and leaf number.When the salt concentration is less than 200mmol/L,silicon addition significantly increased the height of tall fescue(P<0.01).when the salt concentration is 100mmol/L,the height increased to its maximum value of 15.89%,However,tillers per plant were not influenced by Si application.Si application possibly enhances cell elongation and cell division of tall fescue,and encourage the cell growth,and increase the growth of tall fescue under salinization conditions.Secondly,addition of silicon encourager the underground growth of tall feasure under the different salt conditionsIt is decreased with the increase of salt concentration that the root biomass,the total surface of roots,root bulk,the total length of roots and the average root diameter of tall fescue.Exogenous silicon addition the root dry weight,the root shoot ratio,the total surface of roots,root bulk,the average root diameter and the total length of roots was increased.When the salt concentration was less than or equal to 150mmol/L,silicon addition have significantly increased the root biomass,the total surface of roots and the total length of roots of tall fescue roots(P<0.01).The salt concentration of 150mmol/L,meanwhile,the root biomass increased to its maximum value of 34.4%.The increased amplitude firstly decreased and then increased.The salt concentration of 100mmol/L,the total surface of roots increased to its maximum value of 31.3%.The increased amplitude firstly increased and then decreased.The salt concentration of 150mmol/L,the total length of roots increased to its maximum value of 36%.These results suggested that silicon supply could improve the adaption ability of tall fescue in given salinization conditions by altering the root biomass and root features.Third,addition of silicon increased.tall fescue tolerance by improving photosynthetic characteristics,adjusting osmotic substance concentration and oxidation resistance of tall fescue under salt concentrationSilicon application significantly increased photosynthetic rate,stomatal conductance and intercellular CO2 concentration,and decreased transpiration rate with the increase of salt concentration which ranged from 0 to 300mmol/L.Silicon application significantly increased the activity of SOD,CAT and POD.However,Silicon application significantly decreased the malondialdehyde,proline,water soluble sugars content and relative conductivity under salt stress.The salt concentration of 1 OOmmol/L,meanwhile,the content of MDA declined to its minimum value of 18.05%,when the salt concentration ranged from 50 to 200mmol/L,the content of the proline decreased to its value of 23.63%,16.77%,12.25%and 2.78%.The decreased amplitude declined.The result indicated that addition of silicon increased tall fescue tolerance by improving photosynthetic characteristics,adjusting osmotic substance concentration and oxidation resistance of tall fescue,and demonstrated that silicon directly involved in the physiochemical process of tall fescue,and improved the adaption ability of tall fescue in salinization conditions

Mots clés : Silicon; salt concentration; tall fescue; morphological characteristic; biomass; physiologic properties;

Présentation (CNKI)

Page publiée le 10 septembre 2017