Effect Of Manganese Stress On Nitrogen Accumulation And Activities Of Key Enzymes In Nitrogen Assimilation Of Soybean

It is of both theoretical and practical significances to study the effect of manganese stress onnitrogen accumulation and activities of key enzymes in nitrogen assimilation of soybeansystematically for improving soybean yield and quality, and also enrich knowledge aboutnitrogen metabolism because of the important role of manganese in inorganic nitrogenassimilation and nodulation.This work was conducted from2012to2013in Heilongjaing Bayi Agriculture Universityby using sand culture and15N labeling method. Optimal Mn concentration was used as control,and4manganese stress treatments including2manganese deficiency treatments(includingserious stress and light stress which were1/25and1/5of optimal Mn concentration respectively)and2excess stress(including serious stress and light stress which were5and5times of optimalMn concentration respectively) were set to study the effect of manganese stress on key enzymesin nitrogen assimilation, content of related production of nitrogen assimilation, nitrogenaccumulation and composition of soybean on the premise that all soybean could be maturenormally. And the results showed that:Effects of manganese stress on different key enzymes in nitrogen assimilation weredifferent. Compared to control, manganese stress significantly inhibited NR activities in leaves,especially for Mn excess treatments. There were no significant effects of manganese stress onGS activities in leaves, stems and roots and GOGAT activities in in leaves and stems, butdecreased the GOGAT activities in roots. GDH activities in stems and roots were inhibited bymanganese stress, and GDH activities in leaves were increased by Mn excess treatments, the Mndeficiency treatments was opposite.Manganese stress produced certain influence on ammonia nitrogen content. Compared tocontrol, Mn deficiency treatments decreased the ammonia nitrogen content in leaves, stems androots at later development period, and Mn excess treatments was opposite. Manganese stressdecreased the ammonia nitrogen content in pod at pod setting stage, and did not affect that atseed filling period.Manganese stress produced certain influence on ureide contents. Compared to control, Mn deficiency treatment increased the ureide contents in leaves, stems and roots, and Mn excesstreatments was opposite. Manganese stress besides light Mn excess treatment increased theureide contents in pod at pod setting stage, and did not effect that at seed filling period.Manganese stress inhibited nitrogen accumulation of soybean, and changed the distributionproportion of nitrogen among different organs. Compared to control, Manganese stressdifferently inhibited nitrogen accumulation in leaves, stems and roots during the period fromfull-bloom stage to seed filling stage and in pod at seed filling stage, and significantly reducednitrogen accumulation in the whole plant, and the inhibition degree increase with an increase instress degree. The ratio of nitrogen in pod was decreased by manganese stress, then that ofvegetative organs was opposite.Manganese stress inhibited fertilizer nitrogen accumulation in soybean plant and allocationproportion at mature stage. Compared to control, fertilizer nitrogen accumulation in leaves androots during the period from full-bloom stage to seed filling stage and in pod at seed fillingperiod, also reduced the fertilizer nitrogen accumulation in whole plant during the period fromseed filling period to mature, and the inhibition degree increase with an increase in stress degree.The ratio of fertilizer nitrogen in pod was decreased by manganese stress, then that of vegetativeorgans was opposite.Manganese stress significantly inhibited nodulation nitrogen accumulation and allocationproportion at mature stage. Compared to control, nodulation nitrogen accumulation in leaves androots during the period from full-bloom stage to seed filling stage and in pod at seed fillingperiod, also reduced the nodulation nitrogen accumulation in whole plant during the wholegrowth period, and the inhibition degree increase with an increase in stress degree. The ratio ofnodulation nitrogen in pod was decreased by manganese stress, then that of vegetative organswas opposite.Manganese stress significantly reduced the seed yield of soybean. Compared to control,yield component factors including pods per plant, seed per plant,100-seed weight were inhibitedsignificantly by manganese stress(P﹤0.01), which lead to decrement of seed yield. And and theinhibition degree increase with an increase in stress degree.