| In the paper, in order to understand the changes of root system activity and correlation between root system activity with biomass of up-ground parts of the soybean cultivar during different years, so root system bleeding sap weight (BSW) was used as an index of root system activity, In order to understand the changes of root bleeding sap weight (BSW) and organs biomass of above-ground parts during flowering stage (R2), pod setting stage (R4) and seed filling stage (R6) in different years, we chose22soybean cultivars which were bred during in1923～2004. Our aim is to achieve results that can provide useful information to cultivation and the soybean genetic improvement.Under natural conditions in the field, we system at9am to11am of flowering(R2), pod growth(R4)and seed filling stage(R6)of soybean, later sheared cotyledon node of plant to collect bleeding sap and measured its weight. While the up-ground parts of the organ collection, and weighing the fresh weight and dry weight.The results were showed:Root bleeding sap weight (BSW) and organs biomass of above-ground parts had significant difference in soybean cultivars released in different years. Root BSW and biomass of up-ground parts were both increased with years. There was a significant positive relationship between BSW and biomass. The genetic improvement of soybean cultivars had increased of biomass of each organ up-ground parts, as the same time, had led to improve root activity. Root BSW at R2, R4and R6with the biomass of each organ up-ground parts was a positive correlation, and a significantly positive correlation was observed at R4. In addition, root BSW was also significantly positive correlated with biomass of leaf and stem at R4. The ratio of biomass up-ground and BSW were no significant changes at different growth stages, this result showed that root and up-ground parts were coordinated evolution in genetic improvement of soybean cultivars. |
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