| Sugar beet(Beta vulgaris L.) is one of the most important economic crop in north China. At present, many factors greatly hampers the development of sugar beet's production and sugar refinance industry, such as lower single production, un-steady total production, lower sugar content et al. Improving beet production and sugar content can benefit not only the farmers but also the sugar refinance factories. So, making known the mechanism of sugarbeet with high yield and sugar content and putting forward corresponding methods is great significantly.The paper got further research on source-sink metabolism of sugarbeet in different excellent variety, based on the crop source-sink theory and comparative physiology methods. Clarified the characteristics of source-sink relationship and its physiological basis, provided theory elements for breeding new variety with higher yield and sugar content by physiological methods and taking regulator measure. The major results studied in the paper are abstracted as follows:1. LAI and LAD can be regarded as the index of the source capacity of sugarbeet. For the variety with high yield, the stronger source is benefit for morphochoresis of the sink, but shorten the time to achieve the higher photosynthetic fountain. Yet the variety with higher sugar content lasted longer, that is good for enriching of the sink. The key stage for sink capacity foundation is the period of root and sugar grow fast and prophase of sugar accumulation, but in the anaphase the variety with high yield has the faster grow speed and slower sugar accumulation, which leads to the higher water and lower sugar content.2. The peak value of LAI(〉4.3) appeared at the accumulation stage of root and sugar for the beet with yield of 75000kg/hm2 and sugar content of 16%, and descended to 2.4 in telophase after lasted for 20 days. The colony leaf area duration achieved 19.3 m2·d in above stage. In the early stage of root & sugar accumulation, the sink capacity achieved to 700cm3/plant and the enlarging speed of the sink capacity declined rapidly in the evening.3. The chlorophyll content, specific leaf weight, photosynthetic rate had little affection on the foundation of and yield, quality and sugarbeet source.4. The transferring period of organic center had great significance for foundation of the sink. The variety with high yield transferred earlier (in end of July) than which with high sugar.5. The key enzymes activities for sucrose metabolism had difference in defferent organ. SPS is lower in leaves than in root and green-crown and Inv showed the highest activity in petioles. At the same time reducing sugar content is the highest in petioles. The petioles is the important organ in transportation of assimilation product, which transported mainly reducing sugar which synthesized sucrose quickly in the green-crown, then was transported to the root.6. The SPS activity has the same changed trend with the SS and opposite trend with Inv. The Inv activity can be regarded as the index of sink capacity for sugarbeet because of its corresponding change with root increasing speed. The sucrose accumulation was regulated together by SPS, SS reduced activities and Inv synthesis activity. The SPS showed important role in sugar accumulation in root.7. The SPS, SS, Inv gene expressing showed difference in time, space and genotype. Although in the same organ, the enzyme gene expressing showed difference in different variety, and key enzymes for sucrose metabolism showed different expression activity in different growth stage, the same as in different growth stage but in the same organ. The higher enzyme activities are consistent with higher mRNA content. The enzyme with higher activities showed stronger gene expression capacity. The key enzyme for sucrose metabolism can be regulated in transcription level in sugarbeet.
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