A Comparative Study On Nitrogen Efficiency Of Different Genotype Spring Maize Varieties

In order to explore the difference of nitrogen use efficiency of different genotype maizevarieties and reasonable nitrogen fertilizer application,28spring maize varieties in the secondaccumulated temperature zone (2500-2700℃) was used in this study. A split-plot experimentaldesign was conducted, using fertilizer as the main plot and the varieties as the sub-plot. Thenitrogen was applied at6different levels starting from the local experience nitrogen rate (360kghm-2) with a20%reduction to no nitrogen, which were: N5(360kg·hm-2), N4(288kg·hm-2),N3(216kg·hm-2), N2(144kg·hm-2), N1(72kg·hm-2), N0(0kg·hm-2). Acluster analysis ofnitrogen efficiency was made on28spring maize varieties, and the low nitrogen efficiency andlow nitrogen sensitive varieties were determined. Under different nitrogen levels, thephotosynthetic characteristics, agronomic traits, vegetative organs dry matter and nitrogenaccumulation and transfer characteristics, grain yield and quality of maize were analyzed and thedifferences between low nitrogen efficiency genotype and low nitrogen sensitive maize varieties,and the reasonable experience nitrogen level were discussed. The results show that,1. Through cluster analysis of the correlation of nitrogen fertilizer and grain yield, the28maize varieties were classified into high, middle and low yield cluster under each treatment.Depending on According to yield changes of the different maize varieties with differentnitrogen treatment could divide them into different types:(1) low nitrogen efficiency genotype:Zhengdan958(ZD958);(2) low nitrogen sensitivity. Dongfanghong1(DFH1);(3) the doublelow: Huanong101;(4) low nitrogen medium type.2. The yield of low nitrogen efficient variety ZD958maximized at10308.58kg·hm-2underN4treatment, N4application increased grain yield by31.9%; while the yield of low nitrogensensitive variety DFH1maximized at9032.86kg·hm-2under N5treatment, N5applicationincreased grain yield by54.2%. With the decreased nitrogen application, the nitrogen harvestindex (NHI) and nitrogen agronomic efficiency (AEN) of ZD958reached the highest number as46.79%and8.66kg/kg under the treatment of N4, respectively. The highest NHI and AEN ofDFH1were47.11%and12.44kg/kg under the treatment of N5, respectively. For ZD958,nitrogen partial factor productivity (NPFP) and nitrogen use efficiency (NUE) decreasedgradually increased with the decrease of nitrogen; while for DFH1, NPFP gradually increased,but NUE decreased gradually.3. At silking and mature stage, the vegetative organs dry matter accumulation and nitrogenaccumulation of ZD958and DFH1decreased gradually with nitrogen decreasing. The vegetativeorgans (leaf, stem and sheath) dry matter accumulation of ZD958showed increased and then decreased change with the reduction of conventional nitrogen application, and peaked under N4treatment; while those of DFH1were gradually decreased. The nitrogen translocation amount invegetative organs (leaf, stem and sheath) of ZD958and DFH1gradually decreased with thedecreasing of nitrogen amount. With the reduction of the conventional nitrogen application, thetransferred dry matter and their grain contribution rate in vegetative organs of ZD958were:synthesized after anthesis> stem> leaf> sheath, the nitrogen translocation and theircontribution rate to grain in vegetative organs were: synthesized after silking stage> leaf>sheath> stem; while it was different for DFH1, under the N5treatment, it showed: synthesisafter silking> stem> sheath> leaves, and for N4, N3, N2treatments:synthesis after silking>stem> leaf>sheath, while for N1and N0showed: synthesis after silking> stem> leaf> sheath.The nitrogen translocation in vegetative organs and their grain contribution rate of DFH1was:synthesis after silking> stem> sheath> leaf.4. The plant height of ZD958and DFH1reached the highest for265.07cm and257.50cmunder N5treatment, respectively. The total leaf area and stem diameter of ZD958reached thehighest for7051.33cm2and33.00mm under N4treatment, respectively. While the total leafarea and stem diameter of DFH1maximized at6632.13cm2and30.60mm under the treatment ofN5. The agronomic traits of two varieties were similar under the treatment of N5, but thedifferences increased with the amount of nitrogen decreased.The leaf SPAD value and net photosynthetic rate(Pn) of ZD958and DFH1during thewhole growth period maximized on the80d after germination. Underdifferent nitrogentreatments, leaf SPAD value and Pn of DFH1decreased more than ZD958, indicating that theSPAD and Pn of low nitrogen efficiency genotype did not change much under decreasingnitrogen treatment, while it was opposite for the low nitrogen sensitive variety.5.With reduced nitrogen application, obvious effects of grain protein content and littleeffects on starch content and seed oil of both ZD958and DFH1were observed. The the oilcontent and starch content of ZD958was low and protein content was high compared withDFH1.6. For low nitrogen efficiency spring maize varieties, reducing the amount of fertilizer toan appropriate level(N4) did not affect the yield, agronomic traits and the green leaves andphotosynthesis strength of cultivar ZD958, which suggested that the experience fertilizationlevel was higher than needed.