Effects Of Basal-topdressing Ratio And Topdressing Time Of Nitrogen Fertilizer On Growth And Development And Grain Yield Of Super High-yielding Winter Wheat

In order to clarify the effects of basal-topdressing ratio and topdressing time of nitrogen fertilizer on the growth and development and grain yield, and to provide the theoretical basis and technical support for nitrogen regimes of winter wheat, the experiments were carried out during 2010-2011 in Gaocheng city with local winter wheat cultivar Shixin828. The experiments were arranged as split plot arrangement, with nitrogen fertilizer basal-topdressing ratio as main plots (including 3:7, 5:5 and 7:3), and nitrogen topdressing time as split plots (including 4th, 5th and 6th spring-born leaf stage) with total N 240 kg/hm2 applied. The main results were summarized as follows:1. The difference of the number of the culm or spike of winter wheat. The number of culm or spike was increased with the increasing basal-topdressing ratio of nitrogen fertilizer, but the difference of the number of culm or spike among different treatments was not statistically significant. The number of the culm or spike was reduced significantly with the passage of the topdressing time of nitrogen fertilizer.2. The difference of the LAI of winter wheat. The LAI was reached maximum at booting stage. LAI and the maximum of LAI were increased with the increasing basal-topdressing ratio of nitrogen fertilizer, but the difference of the LAI and the maximum LAI among different treatments were not statistically significant. The LAI was reduced obviously with the passage of the topdressing time of nitrogen fertilizer. The LAI of the period from the 20 days post-anrhesis to maturity was increased significantly with the passage of the topdressing time of nitrogen fertilizer.3. The difference of dry matter accumulation. The dry matter accumulation was increased with the increasing basal-topdressing ratio of nitrogen fertilizer, but the difference of dry matter accumulation among different treatments was not statistically significant. The change trends of dry matter accumulation before anthesis and post anthesis were different. The dry matter accumulation before anthesis was reduced significantly with the passage of the topdressing time of nitrogen fertilizer, but the the dry matter accumulation after anthesis was increased with the passage of the topdressing time of nitrogen fertilizer.4. The difference of the leaf chlorophyll SPAD and photosynthetic rate of flag leaf. The leaf chlorophyll SPAD and photosynthetic rate of flag leaf were not influenced with the basal-topdressing ratio of nitrogen fertilizer, but were affected by the topdressing time of nitrogen fertilizer, and the change rules of leaf chlorophyll SPAD and photosynthetic rate of flag leaf were basically the same among the different treatments. The appeared time of the maximum flag leaf chlorophyll SPAD was not same because of the difference of the topdressing time of nitrogen fertilizer, and that of topdressing on 4th spring-born leaf stage was earlier than that of topdressing on 5th spring-born leaf stage and topdressing on 6th spring-born leaf stage. The chlorophyll SPAD and photosynthetic rate of flag leaf increased with the passage of the topdressing time of nitrogen fertilizer after anthesis, and the photosynthetic rate of flag leaf of topdressing on 4th spring-born leaf stage was lower significantly than that of topdressing on 5th spring-born leaf stage and topdressing on 6th spring-born leaf stage in the 30 days post-anthesis. The photosynthetic rate of flag leaf decreased slowly with the passage of the topdressing time of nitrogen fertilizer, and the descend speed of the SPAD after anthesis was different: that of topdressing on 4th spring-born leaf stage>that of topdressing on 5th spring-born leaf stage>that topdressing on of 6th spring-born leaf stage.5. The difference of individual character. The effects of the basal-topdressing ratio of nitrogen fertilizer on the characters of wheat plant was not statistically significant, but the topdressing time of nitrogen fertilizer had statistically significant effect on the characters of wheat plant. The plant height and the numbers of secondary roots were gradually decreased with the passage of the topdressing time of nitrogen fertilizer.6. The difference of grain yield and yield components. The difference of the grain yield, spikes per hectare and grains per spike among the different treatments were statistically insignificant, but 1000-grain weight of wheat was decreased with the increasing basal-topdressing ratio of nitrogen fertilizer. The influence of the topdressing time of nitrogen fertilizer on grain yield and yield components was different among the three levels. Grains per spike and 1000-grain weight of wheat were increased with the passage of the topdressing time of nitrogen fertilizer. Spikes per hectare was reduced with the passage of the topdressing time of nitrogen fertilizer, but the difference of spikes per hectare among different treatments was statistically insignificant. Considering the grain yield components, the grain yield of topdressing on 6th spring-born leaf stage was higher statistically significant than that of topdressing on 4th spring-born leaf stage and topdressing on 5th spring-born leaf stage.7. The difference of water use efficiency(WUE). WUE was not affected significantly by the basal-topdressing ratio of nitrogen fertilizer. For the topdressing time of nitrogen fertilizer, the WUE of topdressing on 6th spring-born leaf stage was higher than the other levels. The interaction of the basal-topdressing ratio and topdressing time of nitrogen fertilizer was not statistically significant, and that showed WUE can improved by adjusting the topdressing time of nitrogen fertilizer in order to achieve the purpose of water saving production.Based on the study, as the basal-topdressing ratio of nitrogen fertilizer was not the main factor, and the interaction of the basal-topdressing ratio and topdressing time of nitrogen fertilizer was not statistically significant, the optimum nitrogen regime for super highly yielding winter wheat in Hebei province is the basal-topdressing ratio 5:5 to 7:3 and topdressing on 6th spring leaf stages with total N 240 kg/hm2 applied.