Evaluation Of Strain Traits Of Northeastern Soybean Core Germplasm And Photosynthesis-related Traits Of High Photosynthetic Rate Varieties

Among more than 10,000 soybean cultivated germplasm resources collected by the Jilin Academy of Agricultural Sciences,a set of 724 soybean core germplasm resources in northeast China was constructed based on basic information such as variety origin,variety type,and agronomic traits.In this study,the core germplasm of soybean in Northeast China was evaluated for plant type and photosynthetic physiology-related traits,and 38 single-leaf high-photosynthetic rate soybean varieties were selected from them.From these,four were selected to analyze photosynthetic physiological characteristics of single-leaf high photosynthetic rate soybean varieties.1.Photosynthetic physiological characterization of soybean core germplasm.The mean values of net photo synthetic rate,stomatal conductance,intercellular carbon dioxide concentration,transpiration rate,instantaneous water use efficiency and transpiration efficiency in the R4 stage of the material population were 22.68 μmol m2 s-1,0.43 mol m-2 s-1,and 255.72 μmol mol-1,7.39 mmol m-2 s-1,54.99 μmol mmol-1 and 3.15 μmol mmol-1,respectively.The initial slope a,half-saturation light intensity Ik and maximum electron transfer rate ETRmax of chlorophyll fluorescence parameters were higher in PS Ⅰ than in PS Ⅱ.The mean value of maximum light absorption Pm in PS Ⅰ was 1.58 and the mean value of maximum quantum efficiency Fv/Fm in PS Ⅱ was 0.843.The mean chlorophyll value of the R5 phase population was 4.33 mg dm-2 and the ratio of chlorophyll a to chlorophyll b was 2.97.2.Soybean core germplasm was studied for plant traits.The varieties with nodes distributed at 9 to 12 nodes had the highest number of nodes.inverted 5,inverted 7 and inverted 9 nodes of varieties with nodes at 5 to 8,9 to 12 and 13 to 16 nodes had the highest correlation with total leaf area with correlation coefficients of 0.792,0.763,and 0.757,respectively.total leaf area was strongly correlated with mean leaf width.3.Photo synthetic physiological studies on high photo synthetic rate varieties.The net photosynthetic rate of high photo synthetic rate varieties reached significant difference from the control after R4 stage.The daily variation of photosynthesis during the pod period showed that the high photosynthetic rate varieties were single-peaked and did not take a lunch break at noon,while the common varieties showed single or double-peaked with a lunch break.The results of light response curves and CO2 response curves showed that the light saturation point of most varieties was around 1500 μmol m-2s-1,and the light saturation point of some high photosynthetic rate varieties could reach 1600 μmol m-2s-1,and the light compensation point of high photosynthetic rate varieties at R4 stage was significantly lower than that of The light compensation point of R4 high photosynthetic rate varieties was significantly lower than that of common varieties.There was no difference between the two groups under both light and CO2 saturation conditions,when the net photosynthetic rate reached about 40 μmol m-2s-1.4.Fluorescence parameters of the high photo synthetic rate varieties were studied.The results of the light energy conversion analysis of PS Ⅱ and PS Ⅰ at the photoresponse stage showed that there was no difference in the actual photosynthetic efficiency between the high photosynthetic rate variety and the common variety PS Ⅰ after the R4 stage,while the actual photo synthetic efficiency Y(Ⅱ)and the relative electron transfer rate ETR(Ⅱ)of PS Ⅱ were significantly different.The results of energy dissipation analysis showed that the fraction of light energy captured for heat dissipation in the high photosynthetic rate varieties after R4 stage was significantly lower than that in the common varieties,and the proportion of active heat dissipation was significantly higher than that in the common varieties.Compared with the common varieties,the high photo synthetic rate varieties had higher net photosynthetic rate,did not take a lunch break at noon,possessed lower light compensation point,higher light saturation point,had stronger light energy utilization ability after R4 phase,stronger light energy conversion ability of PS Ⅱ,stronger ability of light active dissipation of excess energy under strong light,and higher light energy utilization efficiency.