Dynamic variation of nitrogen absorption and distribution of different genotypes in maize under low nitrogen stress

In this investigation,the biomass,nitrogen content,nitrogen accumulation of plant aboveground(whole plant excluding root,WP) and belowground(root) at different developing stages were analyzed under nitrogen applied(N+) and no nitrogen applied(N-) conditions by means of pot cultivation in the field.The results showed that the biomass and nitrogen accumulation of WP and root increased with growth but at different speeds,and from jointing to maturity stage,the WP biomass and nitrogen accumulation were 2~5 and 4~8 times of root,respectively.The mean nitrogen content of WP was higher than that of root but the mean nitrogen content of WP tends to be lightly decreased while that of root maintained stable over stages.The biomass,nitrogen content and nitrogen accumulation were higher or much higher under N+ than N-condition after jointing stage,but the response to low nitrogen stress varied with materials,except the hybrid Nongda 108 appearing obvious heterosis,the inbred line Xu 178 was higher or significantly higher in biomass,nitrogen accumulation in flowering and milk stages than the other inbred lines.The increasing range varied with genotypes,and the coefficient of variations(CV) at flowering stages was 2~3 times higher than that of jointing stage,especially under N-condition and in root,the max CV of root appeared at flowering stage,earlier than that of WP(milk-maturity stage),so the management to promote root system should be earlier.Nongda 108,Xu 178 and L2 had higher biomass than other materials under N-condition,which indicated that they had higher nitrogen use efficiency,and were insensitive to low nitrogen stress.