Study On Water Utilization Characteristics And Adaptability Of Agropyron Mongolicum Under Drought Stress

Taking the dominant species of desert grassland in Ningxia,Agropyron mongolicum,as the research object,the soil moisture was controlled by potted water control in 60-70%,50-60%,40-50%,30-40%and 30-20%in the five levels.The growth and biomass distribution characteristics,stable carbon isotope(?13C)value characteristics,water use efficiency,nutrient accumulation and photosynthetic physiological characteristics of Agropyron mongolicum were studied to explore different water stress.The changes and characteristics of physiological and ecological parameters of different conditions and different stress days preliminarily revealed the water use characteristics and adaptation mechanism.The main findings are as follows:(1)In the growth characteristics of plant,the growth characteristics of the plant increased the growth rate and biomass accumulation rate of the plant,promoted the growth rate of roots and increased the ratio of root to shoot to adapt to water stress.When the soil water content is 50-60%of the field water holding capacity,it is most suitable for the growth and biomass accumulation of the grass.(2)The water use efficiency of Agropyron mongolicum under water stress is to reduce the leaf water content,relative water content and chlorophyll content,increase the water saturation deficit and proline content,and the ?13C value of roots and leaves to maintain strong penetration.The ability to adjust and the ability to resist dehydration,to a certain extent,promote the improvement of water use efficiency of Agropyron mongolicum.(3)The photosynthetic physiology of Agropyron mongolicum decreased Pn,Tr,Fm,Fv/Fm,Fv/Fo,Y and qP,increased NPQ,and adjusted the inflection point of Ci,Gs and Ls,so that Ci and Gs decreased first with the degree of water stress.After rising,Ls rises first and then falls to adjust the factors affecting the decline of Pn.When the soil water content is less than 40%of the field water holding capacity,it is dominated by non-porosity limitation.When the soil water content is greater than 50%of the field water holding capacity,it is restricted by the pores.Leading,ensuring that all photosynthetic physiological activities are carried out underwater stress conditions.(4)Under drought stress,the nutrient elements of Agropyron mongolicum will be gradually distributed to the leaves,and the accumulation of N,P and K contents will be increased under severe water stress.The high K content is balanced by osmotic adjustment and the high N and P contents are promoted to promote leaf photosynthetic The action and accumulation of photosynthetic products adapt to the arid living environment.(5)Plant height,underground biomass,leaf water content,net photosynthetic rate(Pn),chlorophyll b content,PS? potential activity(Fv/Fo),root total N content,leaf full P,these eight indicators in the evaluation of the Agropyron mongolicum.It is preferred to choose drought resistance.The comprehensive analysis showed that the Agropyron mongolicum can increase the root utilization,increase the water use efficiency of leaves and roots,promote the accumulation of nutrients to the leaves,and reduce the activity of photosynthetic physiological activities to maintain high water content and penetration in the body.It has the ability to regulate,endure dehydration,ensure the water state and physiological activity of the aboveground part,promote root water absorption and water use,has excellent water holding capacity and drought resistance,and is suitable for vegetation restoration in arid areas.