Establishment Of A Method For Evaluating Low Iron Tolerance In Soybean And Screening Of Germplasm Resources

In recent years,the issue of food security has received increasing attention due to the impact of trade between China and the United States.It is urgent to improve soybean quality and yield.Iron deficiency Chlorosis(ICD)in soybeans due to iron deficiency in alkaline or calcareous soils severely affects soybean yields.Various countermeasures are available,but high costs and low efficiency have prevented widespread dissemination.In order to explore the germplasm resources of low-iron-tolerant soybean,this study was conducted to further analyze the comprehensive evaluation value of different soybean varieties after being subjected to low-iron stress by establishing a method for evaluating low-iron tolerance in soybean seedlings,and to provide a theoretical basis for in-depth research on the selection and molecular mechanism of low-iron-tolerant soybean varieties.In this study,we used artificial greenhouse hydroponics to simulate the iron-deficient environment in soybean fields,and this experiment established a comprehensive evaluation method for low iron tolerance in soybean seedlings based on physiological indicators.The results showed that the low Fe environment significantly affected the relative chlorophyll content and root tip number of soybean seedlings.The coefficients of 10 traits such as leaf area,total root surface area,and biomass were standardized by principal component and affiliation functions to obtain the comprehensive evaluation value of low iron tolerance in soybean seedlings(I),and the 201 soybean germplasm resources were classified into five classes based on the I value for clustering analysis: 2 low iron tolerance types in class I,26 low iron tolerance types in class II,71 conventional types in class III,99 sensitive types in class IV,and 3 sensitive types in class V.Based on the results of comprehensive analysis,three sensitive varieties(ZDD26282,Flyer and Saline)and two low-iron tolerant varieties(Anhui Huang 506 and Changnong 15)were initially selected.The results of the physiological characteristics of the extreme germplasm resources in response to low Fe stress showed that the leaf Fe content and root Fe content of all five varieties decreased to different degrees after low Fe stress.The low Fe tolerant varieties were significantly higher than the sensitive varieties.The high Fe reductase activity in the root system of the low Fe tolerant varieties was significantly higher than that of the sensitive varieties after low Fe stress.In conclusion,this study was conducted to screen several excellent germplasm resources through the establishment of the evaluation system for low Fe tolerance in soybean seedlings,to further resolve the differences in physiological characteristics of low Fe tolerance in soybean seedlings,and to provide a methodological and material basis for the identification of low Fe tolerance germplasm resources and molecular mechanism research in soybean.