Study On Growth Adaptability Of Switchgrass In Saline-alkali Land Of Northwest Arid Area

In the context of decreasing fossil energy,shortage of arable land resources and environmental protection,the utilization of saline alkali land resources in northwest China to grow energy plants is of great significance to national energy security,land sustainable utilization and ecological environment construction.Switchgrass is considered as one of the most promising energy plants.To clarify the growth adaptability of switchgrass in the saline-alkali environment of the northwest arid area,this study in different ecotype switchgrass as the research object,through field and laboratory test,analyzed the different ecotype switchgrass growth physiological adaptability,water and nutrient absorption and utilization of features,and discussed the effects of different varieties of switchgrass and management mode of saline soil physical and chemical properties.It is expected to reveal the saline alkali land in arid northwest switchgrass growth adaptability of rules,which provides for the theory basis development and utilization of plant resources.The main results are as follows:(1)Switchgrass could adapt to the environment by adjusting its own growth physiological characteristics.Compared with artificial control mode,plant height of lowland and upland switchgrass under natural maintenance mode decreased by 28.59%and 27.89%,tillers decreased by 16.75%and 33.33%,and biomass yield decreased by 23.89%and 27.33%,respectively.In addition,the leaf area,1000-grain weight,and chlorophyll content decreased,proline and malondialdehyde contents accumulated to different degrees,and the enzyme activity of antioxidant system increased accordingly.Lowland switchgrass had stronger growth adaptability than upland switchgrass.Under artificial control,the average plant height,leaf area and dry weight of the upland switchgrass were 80.26%,58.12%and 90.66%of the lowland switchgrass,respectively.Under natural maintenance,the results were 88.02%,76.50%and 86.56%,respectively.Plant height,1000-grain weight and yield of switchgrass were significantly affected by management mode and ecological mode,and their interactions significantly affected tillering and POD activity of switchgrass,thus affecting the growth adaptability of switchgrass.(2)Under the arid saline alkali environment,the water and fertilizer utilization characteristics of switchgrass of different ecological types were significantly different,and the management mode had a significant influence on the water and fertilizer utilization characteristics of switchgrass of saline alkali land.Under the natural maintenance mode,the water consumption of different ecological switchgrass decreased,but the water use efficiency increased significantly.The nutrient content and nitrogen accumulation of switchgrass of different ecological types increased significantly.The phosphorus accumulation in lowland switchgrass increased,but the potassium accumulation in lowland switchgrass decreased.The accumulation of phosphorus and potassium in upland switchgrass was opposite to that in lowland switchgrass.The phosphorus utilization efficiency in different ecological switchgrass decreased significantly,the nitrogen and potassium utilization efficiency of lowland switchgrass increased,and the nitrogen and potassium utilization efficiency of upland switchgrass decreased.(3)The ecological mode and management mode of switchgrass had significant effects on biomass ash and calorific value of switchgrass in saline alkali land.Compared with the manual control mode,the ash and calorific value of lowland switchgrass increased by 8.86%and 2.82%respectively under natural management mode,while that of upland switchgrass decreased by 3.20%and 1.44%respectively.The management mode had no significant effect on the cellulose,hemicellulose and lignin content of switchgrass,indicating that the lignin content of switchgrass was less affected by the environment.(4)The ecological type and planting management mode of switchgrass had obvious influence on the physical and chemical properties of saline and alkaline soil in arid area.Lowland switchgrass cultivars had a great influence on the physical and chemical properties of soil in saline alkali land.The soil pH and total salt content of lowland switchgrass were significantly lower than that of upland switchgrass,and the soil alkali-hydrolyzed nitrogen and available phosphorus content were significantly higher than that of upland switchgrass.Compared with the natural maintenance model,the artificial control and management model could significantly reduce the soil pH and total salt content,and had a better effect on the saline alkali land improvement in the northwest arid region.Therefore,the growth adaptability and ecological effect of switchgrass should be considered comprehensively when it is planted in saline alkali areas of northwest China.