| In order to investigate the effects of spraying urea on the growth among various Genetic wheat under different nitrogen nutrition levels,two field experiments were conducted in Yuzhou,Henan province.The first study was undertaken on wheat urea with mass concentration of 0%,4%(pure N 1.8%)was sprayed on Huaimai 28,Longping 1302,Taixue 12,Pingan 8,Wenmai 19,Yumai 49-198,Zhoumai 16,Fengdecun 1,Longping 9987 at their different growth stages under N application level of 180 kg·ha-1,to explore foliar application of urea on nitrogen concentration,population quantity,population quality and yield in wheat.The second study was undertaken on wheat Yumai 49-198(N high efficiency cultivar)and Zoumai 16(N low efficiency cultivar)which was foliar sprayed 0% and 4% under five nitrogen nutrition levels of N1,N2,N3,N4,N5(0,120,180,240,360 kg·ha-1)to investigate spraying urea on nitrogen concentration,population dynamics and yield of in wheat of different nitrogen efficiency.The result is as follows:1.The effects of foliar application of urea on different organs were different.The variation of nitrogen concentration in stem and sheath was mainly affected by genotype.The wheat population quantity was related to the time of spraying urea.The effects of spraying urea on leaf area index,yield,1000-grain weight and tiller ear rate of different genotype wheat were different.2.The tested wheat were analyzed by cluster analysis according to the urea absorption and utilization efficiency of wheat leaf after spraying urea,and divide them into high nitrogen efficient varieties(Wenmai 19,Longping 1302,Longping9987,Taixue 12,Yumai 49-198 and Fengdecun 1)and low nitrogen efficient varieties(Zhoumai 16,Huaimai 28 and Pingan 8).3.The effects of foliar application of urea on plant nitrogen concentration of Yumai 49-198(N high efficiency cultivar)and Zhoumai 16(N low efficiency cultivar)were distinct under different N nutrition levels.Low nitrogen levels(N1,N2),foliar application of urea could increase the leaf nitrogen concentration of Yumai 49-198,but leaf nitrogen concentration of Zhoumai 16 was decreased.There was same trend between N high efficiency cultivar and N low efficiency cultivar under the conditionof medium nitrogen levels(N3,N4)and high nitrogen level(N5),the leaf nitrogen concentration was decreased,the stem and sheath nitrogen concentration,nitrate content in the stem base and population quantity were increased.4.Foliar application of urea could significantly increase the yield under low nitrogen levels(N1,N2),but the yield was not significantly increased under medium and high nitrogen levels.5.The ability of redistribution of nitrogen in leaves was increased,and the ability of nitrogen redistribution in stem sheath was decreased by foliar application of urea.The ability of nitrogen uptake and utilization of wheat plant was decreased with the increase of nitrogen levels.The nitrogen use efficiency of plant which was spraying urea was significantly higher than that of CK under low nitrogen level.6.The critical nitrogen concentration dilution curve of dry biomass of wheat leaf of different N efficiency cultivar was established: Nc=2.92LDM-0.49(N high efficiency),Nc=2.54LDM-0.24(N low efficiency);and the critical nitrogen concentration dilution curve of wheat leaves of Yumai 49-198 and Zhoumai 16 after spraying urea were: Nc=2.54LDM-0.24(N high efficiency),Nc=2.63LDM-0.27(N low efficiency).7.We can find out the tiller critical nitrogen concentration of different vegetative organs of wheat in different N efficiency when the population quantity began to decline.By comparing the fitting results,we found that there was a polynomial relationship between the tillers number and tillers death critical nitrogen concentration of leaves;there was a power function relationship between tillers number and tillers critical nitrogen concentration of stem and sheath. |
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