Response Differences Of Different Stay-green Maize Inbred Lines Under Nitrogen Stress

Based on the stay-green phenotypic identification and clustering analysis of our countrycommonly used by predecessors in the production of82different types of maize inbred lines.We chosed strong stay-green maize inbred lines178and premature aging type K12asmaterials. The field experiment was set up normal nitrogen (HN) and low nitrogen stress (LN)two processes. Studied the photosynthetic characteristics, the aging process, nitrogenassimilation, the differences of nitrogen use efficiency and their influence on yields andquality of inbred after silking stay-green and non-stay-green maize, further to reveal thephysiological mechanism of stay-green and the relationship between the Stay-Green andmaize nitrogen efficiency. The main results are as follows:1. The influence of nitrogen stress on the stay-green and non-stay-green maize inbredlines of yields reached extremely significant level. Under low nitrogen stress, the yield ofstay-green maize178lower11.32%, while the non-stay-green K12lower19.05%, whichindicates that the stability of yield on stay-green maize was better. However, the performanceof all yield-related traits affected by nitrogen stress is not consistent. In addition, nitrogenstress limit dry matter transportion of different stay-green maize after silking, nitrogen stresson dry matter of K12transit impact was greater, low nitrogen stress made transfer rate of drymatter of178fell1.78%and7.69%drop in K12.2. Nitrogen stress significantly effect green degree of different stay-green maize.Stay-green maize178of green degree was affected by nitrogen stress than non-stay-greenmaize K12smaller. At low nitrogen treatment, the stay-green-degree of178was58.19%,K12was11.41%.0to28days after silking, under nitrogen stress conditions, the solubleprotein content of K12decreased52.80%,178fell46.30%. The high green degree ofstay-green maize inbred lines178that is the hysteresis of ageing process was confirmed thematerial basis of obtain high yield.3. Different stay-green maize protective enzymes SOD, CAT, POD activity in bothnitrogen conditions, the change after silking showed a trend of firstly increased and thendecreased, and reached the peak at14days after silking, but then the protective enzymesactivity of stay-green was significantly stronger than Non-stay-green. The malondialdehyde (MDA) content continue to increase.4. Two types of maize inbred lines K12and178after silking its ear leaf photosynthesiskey carboxylase RUBPCase and PEPCase, both activity show unimodal curve approximationand change. Where in RUBPCase peak appears after7days after silking, while PEPCasemaximum appears in about14days after silking, delayed peak compared RUBPCase,PEPCase peak and longer duration. Two maize inbred lines K12and178, compared over thesame period, the RUBPCase and PEPCase activity of178were stronger than K12, and thisdifference reached a significant level (P<0.01). Indicating that178has strongerphotosynthetic performance, this was also one of the reasons why stay-green maize inbredlines has higher yield than non-stay-green maize nitrogen can improve photosyntheticcarboxylase activity of the two maize inbred lines, but the increase amplitude and period existdifferences. For178, nitrogen on the activity of RUBPCase improve more mainly embodiedin the grouting to maturity, and enhances the activity of PEPCase until late mature was stillobvious. For K12, nitrogen improved RUBPCase more performance in the filling stage.5. Under the condition of low nitrogen stress, the activity of NRA in178still maintain ahigh level, the NRA activity of non-stay-green maize inbred lines K12significantly lowerthan178in low nitrogen. The low nitrogen tolerance index of178was88.68%, K12was80.95%, resistant to the nitrogen of178significantly stronger than K12. In addition, thechanges of NR in ear maize leaf similar to GS,0to14days after silking gradually increasedand then decreased. The peak appeared about two weeks after silking. But under normalconditions of nitrogen, the difference of NR activity in178up to80.25%after silking, whileK12was88.02%. The difference of GS activity in178and K12were46.93%and50.0%,respectively. It suggested that NR was more likely to be affected by nitrogen than GS, and theinfluence of two kinds of enzyme activity showed obvious genotype difference and theinfluence of two type of enzyme activity of nitrogen showed obvious genotype difference.6.Stay-green maize inbred lines178nitrogen partial productivity, nitrogen physiologicalefficiency and resistance to low nitrogen partial productivity index respectively were23.37kg kg-1,29.06kg kg-1and88.68%, were significantly higher than that K12of19.87kg kg-1,24.19kg kg-1and80.95%. This suggested that178had higher nitrogen use efficiency, andmore resilient in low nitrogen environment. But K12has higher nitrogen agronomicefficiency, it show that the nitrogen stimulation effect of K12is better. Under the twonitrogen levels,178grain trans-shipment capacity of various organs to organic nitrogen wasalso stronger.