| Soil salinization is a serious problem affecting China's agricultural production and ecological environment.Saline-alkali land,which of great strategic significance for amelioration and utilization,is not conducive to the growth of crops and garden plants,resulting in a considerable waste of land resources that can be used for arable land and landscaping in our country.Flue Gas Desulfurization Gypsum?simplified as FGDG?is a by-product of scrubbing sulfur from combustion gases in coal-fired power generation plant.As a chemical soil amendment,it has the advantages of low cost,simple operation,and quick effect in improving saline-alkali soil.Scholars at home and abroad have carried out a large number of theoretical and practical researches on the saline-alkali soil amelioration with FGDG,showing broad application prospects.At present,the saline-alkali soil amelioration with FGDG is mainly used in agricultural arable land,focusing on the soil remediation effects and plant growth,and the test plants are mainly crops.However,in addition to planting crops,there is still a large demand for landscaping in saline-alkali areas.The application of FGDG in saline-alkali landscape construction,and the research on garden plants as experimental materials,is still less involved.Besides,the degree of saline-alkali is also quite different,it is necessary to apply an appropriate amount of FGDG in the practical remediation of saline-alkali areas.Therefore,the research takes the different levels of saline-alkali soil in Zhangbei County of Heibei as the research object,plants perennial flowers on the ameliorated soils with FGDG,and focuses on the plant growth and physiology characteristics,to explore the feasibility of planting perennial flowers on the ameliorated soils with FGDG.According to the results of soil indexes in the research,soil with different saline-alkali degrees was collected and divided into three types of soil?moderately salinity soil,heavily salinity soil,and saline soil?.At the same time,three perennial flowers,Hemerocallis hybridus,Aster dumosus and Sedum spectabile,which widely used in Beijing with high ornamental value and plant stress resistance,are selected as test plant materials.Pot experiments were carried out at different application levels according to the theoretical calculation formula of FGDG application amount for saline-alkali soil amelioration.Through analyzing soil indexes,plant growth and physiological indexes,the improvement effect of FGDG on soil with different saline-alkali levels and its influence on the growth and physiological characteristics of the test plants were comprehensively evaluated.The main conclusions are summarized as follows:?1?After applying FGDG,the soil conditions of three different saline-alkali levels have been significantly improved,reducing the soil p H and improving the soil water-soluble components effectively.The content of water-soluble Na+harmful to plant growth is significantly reduced,thus reducing or eliminating ion toxicity to plants.Meanwhile,the content of Ca2+beneficial to plant growth is increased significantly,which improves the soil nutrient.Through multivariate statistical analysis of soil indexes,correlation analysis shows that the application of FGDG significantly affects the changes in the content of water-soluble ions(K+,Ca2+,Mg2+),which beneficial to plant growth.Principal component analysis?PCA?shows soil p H,EC and water-soluble Ca2+indexes are the main factors that affect the comprehensive evaluation.Comprehensive evaluation of the improvement effect of FGDG on three different saline-alkali soils by subordinate function values analysis:saline soil>heavily salinity soil>moderately salinity soil.?2?After planting perennial flowers on the ameliorated soils with FGDG,the plant growth and physiological index data directly proves the feasibility.The three perennial flowers can all survive on the three types of soil.FGDG effectively promotes the plant height growth,improves the photosynthesis and osmotic regulation in cells,reduces the degree of plasma membrane peroxidation,improves the activity of active oxygen scavenging enzyme,increases the absorption of beneficial mineral elements(K+,Ca2+,Mg2+)by plants,and reduces the absorption of Na+,and improves the salt tolerance of the three perennial flowers.Through multivariate statistical analysis of plant and soil indexes,correlation analysis and PCA shows that FGDG significantly improves the salt tolerance of plants through the improvement of saline-alkali soil.Soil water-soluble calcium,antioxidant enzyme systems?SOD,POD,CAT activity?,mineral elements(K+,Ca2+,Mg2+)in plant roots and leaves are the main factors that affect the comprehensive evaluation.Comprehensive evaluation of the planting effects of three perennial flowers on the ameliorated soils with FGDG by subordinate function values analysis:Hemerocallis hybridus>Sedum spectabile>Aster dumosus.?3?The appropriate application amount is the key to give full play to the role of FGDG in improving saline-alkali soil,and different application amount should be set according to plants and soil conditions.The application of FGDG improves the conditions of the three saline-alkali soils while increasing the content of soil water-soluble ions.In addition,only the application of FGDG within a certain concentration range can effectively improve the plant growth and physiological index,and too much or little FGDG will produce inhibition effect instead.The optimum application amount of FGDG for planting three kinds of perennial flowers on moderately salinity,heavily salinized soil and saline soil is 7.5t·hm-2,9t·hm-2 and 15 t·hm-2 respectively. |
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