| sugarbeet (Beta vulgaris L.) is an economic crop, and its root have been used for extracting sugars. This crop is mainly cultivated in northern China, such as Xinjiang, Inner Mongolia and Heilongjiang. Inner Mongolia is the second growing area in China. Further increasing the yield and sugar content of sugarbeet is significant for the development of sugarbeet production, sugar industry and increasing farmers’ benefits.By using comparative physiology, we reported the pattern and correlations for increasing root weight and sugar content among domestic and foreign varieties of sugarbeet, the role of sucrose metabolism related enzymes activity and their gene expression in increasing root and sugar content, the effect and practice of the related nutrients in increasing root and sugar content. In this study, we aimed to illuminate the relationship between increasing root and sugar content, find out the maximize index of sugar yield and realize the role of increasing root and sugar content from SPS and Nutrition metabolism. The theoretic and practical basis of reasonable cultivation and physiological selection can be provided for high yield and sugar content. The results are as follows:1.Compared to the difference of increasing root and sugar content among domestic and foreign varieties of sugarbeet, the yield of the foreign variety of sugarbeet was5.00to14.13percent higher than that of the domestic variety. However, the sugar content of the foreign variety was0.75to1.66percent lower than that of the domestic variety. Root growth was faster in the early growth period. In the latter period, the large growth quantity and slow accumulation of sugars were the causes for the higher yield and lower sugar content in the foreign variety. The growth of root was slower in the early growth period for the domestic variety. In the latter period, the low growth quantity and high accumulation of sugars were the causes for the lower yield and higher sugar content in the domestic variety. 2.The increase in root weight correlated with the increase in sugar content during the growth period of sugarbeet, we think that increasing in root weight and sugar content conformed to a logistical rule. Basic characterization showed that sugar content increased following the increasing in root weight, but the increase was slow during the initial stage and became very quick from the leaves growth period to the roots and sugar growth period.The relativity between root weight and sugar content were not the same in different growth periods. At the seedling stage, sugar content did not correlate with root weight. During the leaves rapid growth period, the sugar content significantly decreased following the increase in root weight when the root weight exceeded390.63g per plant. In the period of the roots and sugar growth, the decreased amplitude significantly accelerated when the root weight was more than939.95g per plant. In the period of sugar accumulation, the decreased amplitude significantly accelerated when the root weight was more than939.95g per plant. However, a decrease in sugar content occurred when the root weight was over1056.76g per plant.3. It was very important that the enzymes related to sugar metabolism for the root weight and sugar content in different growth stages and different parts of the sugarbeet. We found that sucrose phosphate synthase activity was obviously related with sugar content. In roots, the sucrose synthetase synthesis activity was positively correlated with sugar content. The SS decomposition was markedly lower than the synthesis. The relative activity of invertase in the root was low. In leaves, the invertase and SS decomposition were obviously higher than the SPS and SS synthesis activity. From the leaves rapid growth period, root and sugar growth period to the harvesting stage, the results showed that the sugar content in the roots gradually increased following the development progress, along with a gradual increasing in SPS activity.By qPCR analysis,we found that SPS expression in roots were positively correlated with SPS activity. SS is an enzyme with a high expression level, SS synthesis activity is having dominant effect in bidirectional enzyme characterization, and SS synthesis activity was positively correlated with sugar content. The expression and activity of invertase was low in the roots. The expression of invertase enoding gene in leafstalk also were lower than the leaves, however its activity were similar in them, So phosphorylation modification regulation may be one of the reasons for the high activity in leafstalk. At the same time, high expression of invertase encoding gene showed in group with lower sugar content.4. Through a two-way analysis, root weight was moderately correlated with root Na and K contents at the harvesting stage. Sugar content was positively correlated with root P, Mn, B and Cu contents, and negatively correlated with N, K and Na content. We also found that Mg and Fe affected SPS activity in sugarbeet.5. N, P, K, Cu, Mn, Mg and Zn contents were highest at the seedling stage. Iron content was the highest during the growth period of root and sugar accumulation. The greatest absorption of nutritional ingredients was during the period of leaves growth. To produce1t sugarbeet needed2.69kg N,0.776kg P,4.067kg K, and the ratio among N, P, K was1:3.50:5.30. To produce1t sugarbeet needed377.76g Fe,2.1123g Cu,14.424g Mn,884.050g Mg and5.160g Zn. To produce1g sugar needed15.733kg N,4.484kg P,23.784kg K,2.200g Fe,12.339mg Cu,0.084g Mn,5.160g Mg and32.830mg Zn.6. We also carried out the regulation measures to prove the results according to the absorbing properties nutrients.(1) according to the quantity required of N, P, K, we think that the yield and sugar content can be respectively increased16.10%and0.93°compared with control.(2) During the period of leaves rapid growth, spraying KH2PO4and ZnSO4or KH2PO4and MgSO4had a significant effect; the yield, sugar content and sugar yield were respectively increased from8.88%to9.30%,0.51%to0.55%and12.53%to13.25%. In the root and sugar growth period, spraying KH2PO4and NaB4O7or KH2PO4and MnSO4also had a significant effect; the yield, sugar content and sugar yield were increased from5.89%to6.90%,0.85%to1.04%and12.31%to12.39%, respectively. |
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