Effect Of Light,Nitrogen And Their Interaction On Matter Production,Carbon And Nitrogen Metabolism Of Maize

Field experiment was conducted using maize cultivar YY22 with three nitrogen levels(N1:0 kg ha-1,N2:120 kg ha-1,N3:240 kg ha-1)and two light treatments(L1:no shading,L2:shading 14 days after the day 3 days before tasseling)to study the effects of light,nitrogen and their interaction on carbon and nitrogen metabolism,matter production of maize.The main results are as follows:1.The photosynthetic rate(Pn)of ear under leaf L2 was lower than L1,and the intercellular CO2 concentration(Ci)was higher than that of L1;At the same time,with the increasing of N application,the Pn was rising and Ci was falling under different light processing.2.Compared with L1,the content of chla was lower,chlb and total chlorophyll content were increased,chlorophyll a/b value was smaller under L2.But the content of chla,chlb,total chlorophyll and chla/b were increased with the increased of N application under L2.3.Compared with L1,the activity of nitrate reductase(NR),glutamine synthetase(GS)and sucrose synthetase(SS)were decreased of L2 under the same N application.And the capacity of nitrogen absorption and assimilation of plant were reduce,the plant nitrogen accumulation in quantity and soluble sugar content in leaf and stem were reduce too.Under L2,with the increase of N application,the activity of NR,GS and SS were increased,which kept the plant have a capacity of nitrogen assimilation during the period of shading,soluble sugar content in leaf and stem were increased too.4.The dry matter accumulation of maize was L1 > L2 under the same N application.With increasing of N application,the dry matter accumulation increased significantly under the same light processing.The dry matter distributed in corn grain under L1,but it was main corn main distributed in stem under L2.And with increasing of N application,the proportion of dry matter in stem was reduced and the grain percentage increased.Which showed the dry matter would be increased under a high N application during weak light.5.Light,nitrogen and their interaction has a significant influence on corn yield.The yield of corn was L1 > L2 under the same N application;corn yield was N3 > N2 > N1 under the same light processing.Under the L2,with the increase of N application,the yield increased more significant.The kernels per row and kernels per ear were decrease but with the increase of N application it would increase under L2.6.Nitrogen treatments had no significant effect on the grain quality,light treatments had significant impact on grain protein and starch content.L2 grain protein content increased and the starch content decreased under the same N application.