Effects Of Nitrogen Application On Its Absorption And Utilization Of Two Winter Cultivars With Different Spike Types

The population physiological characteristics of both large spike-type cultivar (Lankaoaizao8)and small spike-type cultivar(Yumai 49-198)were stuied under field conditions,and the regulating effects of nitrogen management were investigated as well.The main results are as follows:1.Nitrogen application rates had a direct effect on the development of colony and the same trend in the changes of population was observed in both cultivars.With the increasing of Nitrogen application rates,the colony population and LAL increased during wheat development because of slower senescence,especially N3(180 kg hm^-2)treatment with the highest value(except over winter of Lankaoaizao8),then descending.There were differences between two cultivars in population development.Lankaoaizao8 had fewer culms than Yumai 49-198 per unit area after booting stage,but it could main higher LAI during grain filling because of better light condition in canopy and slower senescing of leaves.2.Nitrogen application rates had a definite effect on on Nitrogen application rates in both cultivars.With the increasing of nitrogen application rates,N accumulated increased at jointing stage,anthesis stage and mature stage,and N4(360 kg hm^-2)treatment reached highest value.N accumulation amount and Protein content had the same trend in mature stage.Protein yield increased with nitrogen level treatments,especially N3(180kg hm^-2) treatment with the highest yield,then descending.Lankaoaizao8 had fewer N accumulation amount,grain N content and protein yield than Yumai49-198.In addition,the relation of N-utilization application and Nitrogen application rates is conic,so is N-harvest index. Value of N-utilization application and N-harvest index is largest on N₃,then descending.That indicated that the right Nitrogen application rates could gain higher N-utilization application and N-harvest index.There were differences between two cultivars in N-utilization application and soil contribution application.N-utilization application of Lankaoaizao8 was distinctly smaller than Yumai 49-198,and its soil contribution application was higher.3.Physiologic accommodation of winter wheat was obviously affected by Nitrogen application rates.Nitapplication reductase(NR)activity,glutamine synthetase(GS)and soluble protein content in flag leaf increased when Nitrogen application rates enhanced,and the value is largest on N₃.The difference between treatments were significant at later stage. That indicated that N metabolic activity was strengthened.There were differences between two cultivars.NR activity of Lankaoaizao 8 descended more quickly at the whole grain-filling stage.GS activity of was very small between two cultivars at flowering stage and early filling stage,and GS activity and solube protein content of Lankaoaizao8 were higher.4.Nitrogen application rates had a evident effect on C-N metabolic characteristics,the fitting Nitrogen application rates increased the amounts of re-transported storage matter and nitrogen and the application of transported storage matter and nitrogen in the leaves and leaf sheaths and the total amounts of re-transported storage matter and nitrogen and the total applications of transported storage matter and nitrogen in winter wheat before flowering, and also increased nitrogen contents in the kernels and contribution of total remobilization of pre-anthesis stored nitrogen to grain.The effect of nitrogen was the most distinct on N₃. There were differences between two cultivars,and amount of post anthesis transferring. intograin and Contribution of post anthesis assimilates to grain weigh of Lankaoaizao8 was higher.5.Nitrogen application rates had a different affected chI,Car,F_v/F_o,F_v/F_m,qp and q_N of flag leaf in two wheat varieties with different spike types to same content.Chlorophyâ…¡contents increased when more nitrogen was applied at a certain range,especially N₃(180 kg hm^-2)treatment with the highest value,then descending.ChI,Car,Ch1a/Ch1b,Ch1/Car of flag leaf in Lankaoaizao8 were higher than in Yummai 49-198 in the late filling stage,which could allieviate the degradation of châ… ,stimulate increasing of photosynthesis. PSâ…¡activity(F_v/F_o)and the maximal quantum efficiency of PSâ…¡photochemistry(F_v/F_m) increased when more nitrogen applied,especially N₃(180kg hm^-2)treatment with the highest value,then descending.In addition,qp of flag leaf in two varieties increased when nitrogen applied was more,but q_N descended.F_v/F_o,F_v/F_m and q_P of flag leaf in Lankaoaizao8 than in Yumai 49-198 in the whole filling stage,but q_N of Lankaoaizao8 was lower at heading and flowering stage.6.The grain yield characteristics were obviously affected by nitrogen.Both cultivars showed N3＞N2＞N4＞N1.When Nitrogen application rates increased,the kernels per united area and per spike increased,and N₂,N₃treatment with the highest value,then descending.When Nitrogen application rates enhanced,1000-kernal weight descended,and N₁ treatment with the highest value.The kernels per united area of Lankaoaizao8 was fewer 234.89×10⁴ than those of Yumai 49-198,and 1000-kernal weight was lower 1.68 g.But per spike was more 7.06 than that of Yumai 49-198.Although per spike of Lankaoaizao8 had evident advantage,the grain yield was lower 678.9 ha^-1than that of Yumai 49-198 with the higher kernels per united area and 1000-kernal weight.Based on the above results,the culturing technique suitable to different spike-type cultivars were presented to obtain the high-yield and low cost.As for Lankaoaizao8,seeding was opeapplicationd with enough soil moisture so that seed could sprout wholly and sufficient seedings could be guaranteed.Nitrogen should be applied at the jointing stage to enhance the ratio of effective tillers to take the advantages of its higher photosynthesis capacity.As to Yumai 49-198,basic seedings should be controlled properly to reduce the ineffective tillers in the initial period.Nitrogen should be applied at jointing stage to stimulate polarization processes,harmonize the relationship of colony and individual, decrease the sterile spikelets and raise effective ones,improve photosynthesis capability in the late filling and prolong grain-filling duration.