| Cultivated soybean was separated from wild soybean by artificial directional selection under natural environment and cultivation conditions.in the process of evolution,soybean seed vigor and physiological characteristics of seed germination changed.Wild soybean has important utilization value in soybean breeding because of its rich genetic background.In this study,three types of soybean seeds(wild,semi-wild and cultivated)were used as experimental materials to compare the seed vigor and physiological indexes of germination process,and to analyze the changes and differences of seed germination of different evolutionary types of soybean varieties.in order to provide reference basis for soybean variety breeding.The test results are as follows:1.With the extension of germination time,the 100-seed weight,germination index and vigor index of cultivated soybean were the highest,indicating that the germination ability of cultivated seeds was better than that of wild and semi-wild seeds,and the dry weight of cultivated cotyledons was the highest.the Hypocotyl of wild soybean is longer than semi-wild and cultivated,which is more favorable for soybean cotyledon germination.2.During the period of water absorption and germination of soybean seeds,the relevant physiological indexes were compared.in the germination stage,the starch content began to decrease,and the soluble sugar content showed a downward trend,indicating that more soluble sugar was consumed in the germination stage.The content of soluble protein in cotyledons of cultivated type was higher than that of semi-wild type,and that of wild type was the lowest,indicating that soluble protein could provide energy and metabolic intermediates for cultivated soybean seeds during germination.The content of total nitrogen in cotyledons showed a downward trend,the content of total nitrogen was the lowest on the 7th day of germination,the content of free amino acids increased at first and then decreased,and the content of amino acids was the lowest on the 5th day.Among the different evolutionary types,the contents of total nitrogen and free amino acids in cultivated soybean were the highest,followed by semi-wild and wild.3.With the germination of soybean seeds,the content of nitrate nitrogen in cotyledons decreased,the content of nitrate nitrogen had little difference among different evolutionary types,the content of ammonium nitrogen decreased at first and then increased,and the content of ammonium nitrogen was the lowest on the fifth day.the content of ammonium nitrogen was the highest enzymatic activity is revealed in cultivated soybeans,followed by semi-wild type and wild type.4.With the seed germination,the absolute electrical conductivity and Malondialdehyde(MDA)content increased,The highest enzymatic activity is revealed in cultivated soybeans,followed by semi-wild type and wild type.The results showed that the soybean cotyledons gradually senescent with the extension of germination time.The activities of superoxide dismutase(SOD),catalase(CAT)and peroxidase(POD)in wild,semi-wild and cultivated soybean cotyledons increased with the process of germination.The activities of superoxide dismutase,catalase and peroxidase in soybean cotyledons were from the highest to the lowest,the levels of enzymatic activities are in the order of Cultivated soybeans,Semi-wild type,and wild type.5.During seed germination,the activities of key enzymes of nitrogen metabolism in cotyledons of soybean: glutamine synthase(GS),glutamate synthetase(GOGAT)and glutamate dehydrogenase(GDH)showed a downward trend,with the highest activity on the first day;the activity of nitrate reductase(NR)increased at first and then decreased on the fifth day;the activities of GS,GDH,GOGAT and NR in cotyledons were the highest in cultivated soybean,followed by semi-wild soybean and the lowest in wild soybean.The activity of nitrogen metabolism enzymes in cotyledons of cultivated soybean was higher in the process of soybean evolution. |
