| Under the influence of natural environment and cultivation conditions,cultivated soybeans were isolated from wild soybeans by artificial directional selection.During the evolution of soybeans,the nitrogen metabolism level of root bleeding fluid changed significantly.In this study,the activities of key enzymes in nitrogen metabolism,contents of nitrogen compounds and leaf photosynthesis in the root fluid of different evolutionary types of soybeans（wild,semi-wild,semi-cultivated and cultivated）during the whole growth period were compared,and the relationship between the activities of key enzymes in nitrogen metabolism and leaf photosynthesis in the root fluid of soybeans was analyzed,so as to provide theoretical reference for the efficient use of nitrogen in soybeans and the breeding of nitrogen-efficient varieties.The experimental results are as follows:1.Changes in activities of key enzymes in liquid nitrogen metabolism in root wound fluid of soybean of different evolutionary typesNitrate reductase（NR）activity showed a single curve in the reproductive growth stage.The cultivated type was higher than the semi-wild type and the semi-cultivated type,and the wild type had the lowest NR activity.The activity of Glutamune synthase（GS）increased first,then decreased,and then increased and then decreased.The overall activity of cultivated soybean was higher than that of the other three types.The activity of Glutamate synthase（GOGAT）showed a single curve,and the cultivated type was higher than the other three types.Glutamate dehydrogenase（GDH）activity showed a single curve,the overall pattern of soybean wound flow are in the order of cultivated type,semi-cultivated type,semi-wild type,and wild type.2.Changes of nitrogen compounds in root fluid of different evolutionary types of soybeanThe contents of soluble protein,free amino acid and soluble sugar in root fluid from the highest to the lowest,the levels of enzymatic activities are in the order of cultivated type,semi-cultivated type,semi-wild type,and wild type during the whole growth period.The contents of ammonium nitrogen and nitrate nitrogen in V4 stage were in the order of cultivated type,semi-cultivated type,semi-wild type and wild type,and in R2-R8 stage are in the order of wild type,semi-wild type,semi-cultivated type and cultivated type.Total nitrogen content in V4 stage are in the order of wild type,semi-wild type,semi-cultivated type,and cultivated type,and in R2-R8 stage are in the order of cultivated type,semi-cultivated type,semi-wild type,and wild type.3.Changes in leaf photosynthesis of different evolutionary types of soybeanThe leaf net photosynthetic rate（Pn）,transpiration rate（Tr）and stomatal conductance（Gs）of cultivated,semi-cultivated,semi-wild and wild soybean showed the same trend,and the overall curve showed a single peak,with the peak value at R4,which was the highest in cultivated soybean in all periods.The variation trend of intercellular CO2concentration（Ci）in leaves of the four soybean types was basically the same,which showed a trend of decreasing and then increasing.The maximum concentration appeared in R8 stage,and the highest concentration was found in wild type in all periods.4.Correlation between the activities of Key enzymes in liquid nitrogen metabolism and leaf photosynthesis in different evolutionary types of soybeanThere was a positive correlation between the enzyme activity of liquid nitrogen metabolism and net photosynthetic rate（Pn）,transpiration rate（Tr）and stomatal conductance（Gs）during the whole growth period.Semi-cultivated and cultivated soybeans had extremely significant positive correlation with net photosynthetic rate（Pn）,transpiration rate（Tr）and stomatal conductance（Gs）during the whole growth period,while wild and semi-wild soybeans had significant positive correlation or extremely significant positive correlation or positive correlation but no significant correlation... |
