Influence Of Nitrogen Control On The Key Enzymes Of Sugar Beet(Beta Vulgaris.L)Nitrogenous Assimilation And Sugar Metabolism

Abstract There are great influences of different forms, different levels nitrogen on the yield and quality of sugar beet, the mechanism lies that nitrogen plays an important role in nitrogenous assimilation and sugar metabolism. The results showed that there were different influence of nitrogen sources on nitrogenous assimilation enzymes. Nitrate reductase activity raised with the nitrate nitrogen raised. In whole growth duration, nitrate reductase activities have the same M梥hape trend in endogenous or exogenous substrate. Ammonium nitrogen inhibited NR activity: NR activity was lower in endogenous substrate when ammonium nitrogen was used, and the correlation between NR activity and ammonium nitrogen levels wasn?t positive. But NR activity raised with the anunonium nitrogen levels raised in exogenous substrate. Glutamine synthetase activity raised with the nitrate nitrogen raised too, In whole growth duration, Glutaniine synthetase activities have the single peak curve trend in roots or leaves. Animonium nitrogen prompted GS activity: the correlation between GS activity and ammonium nitrogen was positive, GS activity in roots was higher than in leaves. NR activity of different proportion of NOb/NH~4 was different: NR activity raised when proportion of N03 in mixed nitrogen source raised, and NR activity of N&3/NH~4?:O was highest, but NR activity of NO7NH~4?:l was highest in period of peak absorbed nitrogen. In roots and leaves, GS activity change of different proportion of NOb/NIt4 was different: GS activity raised when proportion of N03 in mixed nitrogen source raised in leaves, but its activity raised when proportion of NH~4 in mixed nitrogen source raised in roots. Influence of the nitrate nitrogen levels on synthesis activity of SS (sucrose synthase )and decomposition activity of SS, nitrate nitrogen can improve the synthesis and decomposition activity of SS to different degree, but nitrate nitrogen can increase the decomposition activity of SS even more. The activity of SS is much higher in roots than in leaves, this accounts that synthesis activity of SS is main to synthesize sugar in sugar beet roots. But the activity of SPS (sucrose phosphate synthetase) is main to synthesize sugar in leaves and the activity of SPS is much higher than that of SS in leaves, that is inverse in roots. Compared to nitrate nitrogen, ammonium nitrogen can increase the synthesis activity of SS in roots and leaves, but its activity decreased when aminonium nitrogen concentration exceed 8.0 mmol/L, SPS activity of roots or leaves decreased when nitrogen concentration reached 12.8mmollL. The change trend of SS activity of roots or leaves was similar to that of sole nitrogen source when different nitrogen sources were mixed. Compared to the sole nitrogen source, enhanced ammonium nutrition(EAN) could increase SS and SPS activities of roots or leaves, enzymes activity of NOb/NH~4?:1 were the highest In sugar beet growth duration, a 梐mino nitrogen concentration in roots reached its peak at ii the stage of root growth. a -amino nitrogen concentration raised with the sole nitrogen source concentration raised. The influence of different nitrogen source on a 梐mino nitrogen was different: the effect of ainmonium nitrogen on a -amino nitrogen was bigger than that of nitrate nitrogen, and in similar nitrogen levels, different proportion of nitrate nitrogen and animonium(NOb/NH~4), a -amino nitrogen raised with the rate of ammonium raised. The influence of different nitroge...