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Synergistic Effects Of Salt-alkaline Mixed Stress On Seed Germination And Seedlings Growth In Switchgrass

Posted on:2015-12-28Degree:MasterType:Thesis
Country:ChinaCandidate:Y LiuFull Text:PDF
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Bioenergy crop, switchgrass (Panicum virgatum L.) was usually grown in themarginal land to avoid competition with food crops. Salt-affected soils are present in a largeportion of the marginal Land. Therefore, researching the effects of salt and alkaline stress onswitchgrass, exploring the mechanisms of salt-alkaline tolerance and constructing suitablemodels of the effects of salt-alkaline stress on switchgrass are important goals. Using a fullcombination design and one control, seventeen salt-alkaline mixed stress treatments atvarying combinations of salinity and pH were established. The three cultivars of switchgrasswere submitted to the designed treatments. The germination index, the plumular and radicularlength and the contents of soluble sugar, MDA and proline were measured. The equivalentcoupled effects was used to construct the new salt-alkaline mixed stress model.We found that:1)Switchgrass was found to be capable of germinating and surviving well under alltreatments at low pH (pH≤8.3), regardless of the level of salinity.2) The germination and survival of this species is related to its ability to accumulateorganic solutes (proline and soluble sugar).3) The deleterious effects of high pH or salinity alone were significantly less than thecombined effects of high pH and salinity. We conclude that reciprocal enhancement betweensalinity and pH stress is a characteristic feature of salt-alkali mixed stress, which isdemonstrated by the constructed models.4) The salinity and pH had synergetic effects on the germination percentage, germinationindex, plumular length and the contents of soluble sugar and proline, whereas the salinity andpH exhibited antagonistic effects on the radicular length of switchgrass.5) The synergetic and antagonistic effects of salinity and pH are new valuable models,which should be considered when evaluating the strengths of salt-alkali mixed stress.
Keywords/Search Tags:Switchgrass, pH, Seed germination, Synergistic effect, Antagonistic effect
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