Study On The Mechanism And Regulation Of Nitrogen Assimilation And Sucrose Metabolism Of Sugar Beet

In this dissertation,Tianyan 7 of NZ sugar beet was selected as experimental sample,and experiments were made in the campus and practice base of NEAU from 2006 to 2007. Experimental factors were as follows:NO₃^--N,NH₄⁺-N,MgO and P₂O₅.In experiments the quadratic rotation-orthogonal combination design was adopted.We comprehensively and systematically studied on dynamic changes and regulation approaches of key enzymes and main products of nitrogen assimilation and sucrose metabolism of sugar beet,the mechanism of nitrogen assimilation and sucrose metabolism,further analyzed interaction mechanism between nitrogen assimilation and sucrose metabolism,and announced the regulation effect of nitrogen, phosphorus and magnesium fertilizer on nitrogen assimilation,sucrose metabolism,yield and quality.This dissertation will fill in the infrastructure data of sugar beet physiology,provide theoretical basis for identifying,evaluating,reforming and using germplasm resources,and making reasonable cultivation measurement.Results of this experiment are as following:1.The variation laws of the activities of key enzymes of nitrogen assimilation were different at each stage and location of sugar beet.In leaves the peak values of enNRA,GSA,GOGATA and GDHA were all before the tuber growth stage.In roots GOGATA was higher at the prophase and GSA and GDHA were bigger in the late period.In location,GSA of roots at other stages was much higher than that of leaves besides at seedling stage;GOGATA of leaves was very higher than that of roots besides in the foliage formation period and the end period of the foliage formation;and GDHA of leaves was bigger than that of roots.And the dynamic changes of GSA,GOGATA and GDHA in roots and leaves were all different.The relationships were different among the key enzymes of nitrogen assimilation.Before the foliage formation period there were significantly positive correlations between enNRA and exNRA,NRA and GSA and GSA of roots and leaves. After the foliage formation period there were significantly negative correlations between GSA and GOGATA.At different stages the relationships were different between the activities of key enzymes of nitrogen assimilation and yield and quality.Before the root growth stage there were closely relationships between them and yield and sugar yield,and from the root growth stage extremely correlations were observed with sugar contents.And before the foliage formation period the key enzymes activities of nitrogen assimilation in leaves were significantly related with yield, from the foliage formation period to the end stage of tuber growth there were significant correlations between GSA of roots and yield and quality,and at the sugar accumulation stage NRA became the main factor.In the end stage of tuber growth the effect of GSA of roots on yield and quality were highest.The dynamic changes of the main products contents of nitrogen assimilation of sugar beet were different.The contents of soluble protein of roots slowly decreased before the root growth stage,quickly increased after the root growth stage,and at the sugar accumulation stage got the highest level.The contents of soluble protein of leaves increased with growth and development stage,decreased from seedling stage to the end of August,after the end stage of tuber growth increased.The total contents of nitrogen of leaves decreased from seedling stage to the end period of the foliage formation,from the end period of the foliage formation to the root growth stage increased,and till the sugar accumulation stage decreased.At different stages the correlations among the main products of nitrogen assimilation were different.At different stages the relationships were different between the contents of main products of nitrogen assimilation and yield and quality.From seedling stage to the sugar accumulation stage the main products of nitrogen assimilation were related with yield and quality.And at the root growth stage the correlation coefficients between the contents of total nitrogen and soluble protein and yield and quality attained to the higher level at the same time,so the contents of total nitrogen and soluble protein can be used as reference indexes to predict yield and quality of sugar beet in the root growth period.And at different growth and development stages there were different correlations between the key enzymes and main products of nitrogen assimilation of sugar beet.2.The variation laws of the key enzymes activities of sucrose metabolism were different at each stage.In roots,the dynamic changes of SPSA,NIA,AIA and the decomposition activities of SS were similar,and in leaves the ones of SPSA and SS were similar.The dynamic changes of activities of other key enzymes were different.In sampling location,SPSA,the synthesis activities of SS(besides seedling stage) and NIA of roots were higher than that of leaves at whole growth and development stage;at the middle and late stage the decomposition activities of SS of roots were smaller than that of leaves,at other stages were higher than leaves;AIA of roots were higher than leaves at seedling and late stage,at the middle stage were lower leaves.With SPSA,in roots the synthesis activities of SS at each stage were higher than SPSA except for were lower than SPSA;in leaves the activities of them were very close.With AIA,the maximums of NIA of roots and leaves were all lower than AIA.With NIA and AIA,the decomposition activities of SS of roots were all lower than NIA and AIA besides in the beginning period of the foliage formation, and the activities of 3 enzymes in leaves were all low,and the diversity were small.At different stages the correlations of the key enzymes of sugar metabolism were different.At seedling stage there were significantly positive correlations among the decomposition enzymes of sugar metabolism of roots;in the beginning period of the foliage formation there were significantly positive correlations between SPSA and the synthesis activities of SS in leaves and the decomposition enzymes of leaves,and in roots there were significantly positive correlations between the synthesis and decomposition activities of SS;in the foliage formation period there were correlations among each enzymes besides the synthesis activities of SS;there were significantly positive correlations among each enzymes of roots and leaves in the end period of the foliage formation and among each enzymes of roots at root growth stage;there were correlations between SPSA and the synthesis activities of SS in roots and each enzymes.In the end stage of tuber growth there were significant correlations between SPSA of leaves,the synthesis activities of SS of roots and each enzymes of sucrose metabolism at sugar accumulation stage.The dynamic changes of the main products contents of sucrose metabolism of sugar beet were different.The total contents of soluble sugar in roots and leaves formed a single peak curve,and their peak values were in roots growth period and the end period of the foliage formation respectively.The fructose contentss of roots changed like wave motion,its troughs were in the foliage formation and roots growth period respectively.The change of fructose contents in leaves was like "V",and its minimum was in the beginning period of the foliage formation.The contents of sucrose in roots gradually increased from seedling to roots growth stage,and in the end stage of tuber growth slightly decreased,but kept higher level till sugar accumulation stage.The contents of sucrose in leaves slowly increased from seedling to the end period of the foliage formation;in the end period of the foliage formation got the maximum;later slightly decreased;from the sugar accumulation stage slowly increased again.At whole growth and development stage the contents of soluble sugar,fructose and sucrose of roots were all higher than those of leaves.At different stages the correlations among the main products of sucrose metabolism were different.And above-mentioned analysis showed:in the foliage formation initial period fructose was the most important product of sucrose metabolism;in the foliage formation period sucrose was uppermost product.At whole stage the contents of fructose in soluble sugar of leaves was higher at all time, and at the same time the contents of sucrose in leaves from the root growth to sugar accumulation stage quickly increased.And at whole stage the contents of fructose and sucrose in roots all changed all together;the contents of fructose and sucrose in leaves all changed together from the root growth to sugar accumulation stage.At different growth and development stages there were different correlations between the key enzymes and main products of sucrose metabolism of sugar beet.To sampling locations there were significant correlations between the key enzymes activities of sucrose metabolism and the main products of sucrose metabolism of leaves at prophase and after the foliage formation period;in the foliage formation period there were significant correlations between the key enzymes activities of sucrose metabolism and the main products of sucrose metabolism of roots.With stages at seedling stage the decomposition enzymes of sucrose metabolism had significant effect on the products;in the beginning period of the foliage formation the contents of main products were affected significantly by the decomposition and synthesis enzymes;in the foliage formation period the effect of the synthesis enzymes was slightly in the ascendant;in the end period of the foliage formation effect of the decomposition enzymes on main products became more important;at root growth stage and in the end stage of tuber growth effect of the synthesis enzymes on main products was higher than the decomposition enzymes.At all stages there were almost significant correlations between the key enzymes activities of sucrose metabolism and yield,sugar contents and sugar yield.At all stages there were significant correlations between the main products of sucrose metabolism and yield,sugar contents and sugar yield besides at seedling stage and in.the end stage of tuber growth.At the same time the main products were all related extremely with sugar contents,and at root growth stage were all significantly related with yield,sugar contents and sugar yield.3.At different growth and development stages there were different correlations between the key enzymes of nitrogen assimilation and of sucrose metabolism of sugar beet.The relationships between NRA and the decomposition activities of SS and SPSA of roots were close at prophase, and at late stage there were significantly positive correlations between NIA and AIA.From the end period of the foliage formation to the end stage of tuber growth there were significantly positive correlations between GSA of roots and the key enzymes of sugar metabolism of roots at different levels.GSA of leaves were closely related with the key enzymes of sugar metabolism at initial and telophase stage,and were related with the key enzymes of sugar metabolism of leaves in the middle stage.At different stages GOGATA of leaves were related with the key enzymes of sugar metabolism at different levels. At different stages the relationships between the key enzymes of nitrogen assimilation and the main products of sucrose metabolism were different.NRA of leaves was related significantly with the fructose contents of roots.The correlations of GSA of roots and the main products of sucrose metabolism were not remarkable.There were significant correlations between GSA of leaves and the contents of fructose and soluble sugar of leaves at the initial and late stage,and in the middle period the relationships between the contents of fructose and soluble sugar were close.GOGATA of leaves were related significantly positively with the main products of sucrose metabolism of roots in the beginning period of the foliage formation,were related extremely negatively with the main products in the end period of the foliage formation,and were related extremely positively with the fructose contents of roots in the end stage of tuber growth.At different stages the relationships of the main products of nitrogen assimilation and the key enzymes of sucrose metabolism were different.At whole growth and development stages there were extremely significant negative correlations between the contents of soluble protein of roots and the enzymes activities of sucrose metabolism of roots.The contents of soluble protein in leaves were related significantly negatively with the enzymes activities of sucrose metabolism of leaves,were related significantly positively with the enzymes activities of sucrose metabolism of roots except for at the foliage formation period were related extremely significantly negatively with the synthesis activities of SS of roots.The correlations between the total contents of nitrogen in roots or leaves and the key enzymes of sucrose metabolism were similar.Effect of SSA and NIA on the total contents of Nitrogen in roots and leaves were all significant.At different stages the relationships of the main products of nitrogen assimilation and the ones of sucrose metabolism were different.In the middle stage the contents of soluble protein in roots were related significantly with the main products contents of sucrose metabolism,in the beginning period of the foliage formation and the foliage formation period there were significantly positive correlations between the contents of soluble protein in leaves and the contents of sucrose and soluble sugar in leaves.The total contents of N in roots were related significantly with the main products contents of sucrose metabolism from seedling to foliage formation period,were related remarkable only with the main products contents of sucrose metabolism from the end period of the foliage formation to the turb growth period.The correlations between the total contents of N in leaves and the main products contents of sucrose metabolism were close from the beginning period of the foliage formation to the end stage of tuber growth.4.The dynamic changes of related physiological indexes of nitrogen and sucrose metabolism in sugar beet were all different.The dynamic changes of C/N in roots and leaves were similar. From seedling stage to root growth stage C/N all increased,decreased slightly after the end stage of tuber growth.At all stages C/N of roots were higher than that of leaves.The contents of chlorophyll decreased from seedling stage to the beginning period of the foliage formation,later quickly rose,in the foliage formation period got the peak value,from 9^th July descended again,till sugar accumulation stage attained to the lowest level.The dry weights of roots increased with the growth and development stage;the dry weights of leaves enhanced from seedling stage to root growth stage,later decreased,after the end stage of tuber growth little increased.The ratio of crown and root decreased with the growth and development stage,was near 1 in the end period of the foliage formation.So it can be used as reference indexes to reflect the status of growth and the center growth of sugar beet.At different stages the relationships between related physiological indexes of nitrogen and sucrose metabolism and yield,sugar contents and sugar yield were different in sugar beet.In the beginning period of the foliage formation and the end period of the foliage formation related physiological indexes were significantly related with yield and quality,and effects of chlorophyll contents,dry weight of roots and ratio of crown and root on yield and quality were larger.And at whole stages related physiological indexes were related extremely significantly with the sugar contents,were related significantly with yield,were related with sugar yield at different levels.5.At different stages regulation effects of NO₃^--N,NH₄⁺-N,MgO and P₂O₅ on the key enzymes activities of nitrogen assimilation and sucrose metabolism were different.There were obvious interactions between two factors,and in interaction the main factor were different.At the same time the contributor of four treatments on the key enzymes activities of nitrogen assimilation and sucrose metabolism were different.And we obtain the different treatment combinations at the highest activities of key enzymes of nitrogen assimilation and sucrose metabolism of sugar beet when the effects of four factors were outstanding.6.Effects of different treatment factors on yield,sugar contents and sugar yield were different. Contributors on yield and sugar yield were all in order:MgO＞NO₃^--N＞NH₄⁺-N＞P₂O₅,and contributor on sugar contents were in order:MgO＞NH₄⁺-N＞NO₃^--N＞P₂O₅.And we obtain the different treatment combinations at the highest yield,sugar contents and sugar yield of sugar beet.