| In order to provide the information for improving grain quality and economic benefit of large-scale wheat production in the rice-wheat rotation system,a field experiment was conducted under the conditions of rice straw returning into the field in the full quantity with a medium-gluten variety Xumai 818 as material. Using nitrogen rate of 225 kg·hm-2 applied at pre-sowing and jointing with the ratio of 5∶5 as the control,the effects of reducing topdressing-nitrogen and reducing basis- and topdressing-nitrogen in balance(reducing nitrogen in balance for abbreviation) on grain yield,quality,nitrogen efficiency and economic benefit of wheat were investigated. The results showed that reducing topdressing-nitrogen by 10%-20% could improve nitrogen efficiency and did not significantly affect on spike number,kernel number per spike,grain yield,economic benefit,grain bulk density,hardness,flour yield,wet gluten content,sedimentation value,protein and its component content,starch and its component content,starch gelatinization characteristics and flour quality characteristics. The reducing basis- and topdressing-nitrogen in balance by 10% each could improve nitrogen efficiency,economic benefit,dough stability time and flour quality parameters,but did not significantly affect on grain yield,yield components and the other grain quality parameters. The model of reducing nitrogen by 20% in balance and the topdressing-nitrogen even at jointing and booting stages could significantly improve 1 000-grain weight,grain yield,economic benefit,nitrogen apparent utilization rate,nitrogen agronomic utilization efficiency,grain bulk density,wet gluten content,dough stability time and flour quality parameters. Excessive nitrogen reduction led to various degrees of reductions in grain yield,grain quality,nitrogen physiological utilization efficiency,nitrogen agronomic utilization efficiency and economic benefit. In conclusion,under the conditions of this experiment,20% nitrogen reduction do not cause yield losses but can achieve the goal of good quality and high efficiency. The results also indicated that nitrogen reduction in balance can be recommended in wheat production. |
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