| In order to provide theory basis for nitrogen fertilizer reasonable use in winter wheat production in the Huang-Huai-Hai plain of China,This study designs two experiments:The study one were in 2014-2015 wheat growing season set with two wheat cultivars?Shannong8355 and Jimai22?and four nitrogen treatments of without applying N fertilizer?T1?;N application rate of 240 kg hm-2 with fertilizer ratios of base to topdressing as 7:3?T2?,5:5?T3?and 3:7?T4?.The effect of nitrogen fertilizer ratio of base and topdressing on NO3--N time-space distribution in soil,apparent nitrogen surplus and deficit amount in soil and nitrogen use efficiency with various growth stages in winter wheat.The study two were in 2015-2016 wheat growing season set with two wheat cultivars?Shannong8355 and Jimai22?and four nitrogen treatments of without applying N fertilizer?N0?;N application rate of 150 kg hm-2?N1?;N application rate of 225 kg hm-2?N2?;N application rate of 300 kg hm-2?N3?,the all the treatments were with fertilizer ratios of base to topdressing as 5:5.The effect of nitrogen fertilizer application rate on NO-3-N time-space distribution in soil,apparent nitrogen surplus and deficit amount in soil and nitrogen use efficiency with various growth stages in winter wheat.The main results are as follows: 1 The effects of nitrogen management on NO3--N time-space distribution in soilWhen nitrogen fertilizer ratio of base and topdressing is same?5:5?,NO3--N in soil is increasing as nitrogen application rate increase,too much nitrogen fertilizer exceeds the limit of the plant's ability to absorb nitrogen,the accumulation of nitric nitrogen in the soil increased the possibility of nitric nitrogen leaching into the lower soil.When nitrogen application rate is same(240 kg hm-2),nitrogen fertilizer ratio of base and topdressing will significantly influence the content and distribution of nitrate nitrogen in the soil profile,will lead on wheat growth anaphase percentage basal surface soil?0 to 40 cm?nitrate accumulation is less,so the nitrogen in soil is difficult to meet the demand of jointing stage to the mature period of wheat to nitrogen,increasing topdressing nitrogen fertilizer can reduced nitrogen loss before jointing stage,and to ensure the jointing stage to the mature period?n peak demand?soil nitrogen supply.2 The effects of nitrogen management on apparent nitrogen surlus and deficit amount in soilWhen nitrogen fertilizer ratio of base and topdressing is same?5:5?,nitrogen apparent surplus increased with the increase of n application rate increased,high nitrogen application manage has much more soil nitrogen surplus amount than other manage,and surplus of nitrogen mainly to deep soil layer in the form of the NO3--N elution.When nitrogen application rate is same(240 kg hm-2),without applying N fertilizer manage and smaller scale nitrogen fertilizer ratio of base has small amount of nitrogen deficiency in sow to jointing stage with winter,nitrogen fertilizer ratio of base too much will increase the surplus quantity of soil nitrogen and increase the chances of leaching;T4?3:7?treatment has small apparent nitrogen surlus in anthesis and maturity period with wheat,other treatment all have apparent nitrogen deficit.3 The effects of nitrogen management on nitrogen translocation from vegetative organs to grain after anthesisWhen nitrogen application rate is less than 225 kg hm-2,the grain nitrogen accumulation quantity is increased by increase of nitrogen application in maturity period of wheat,when nitrogen application rate is less than 225 kg hm-2,the grain nitrogen accumulation quantity and translocation amountfrom absorbed nitrogen before anthesis to grain all reach the highest.When continue to increase the amount of nitrogen application in the 225 kg hm-2,the grain nitrogen accumulation quantity and the rate of nitrogen transfer in the nutrient organ were decreased.There is a difference between the use and absorption of nitrogen in different wheat cultivars,the rate of nitrogen transfer in the nutrient organ and nitrogen absorption amount after anthesis with Jimai22 is higher than Shannong8355 4 The effects of nitrogen management on nitrogen use efficiency in winter wheatWhen nitrogen fertilizer ratio of base and topdressing is same?5:5?,as the nitrogen application rate is less than 225 kg hm-2,the nitrogen use efficiency of each quantitative index is increased by increase nitrogen application of wheat;as the nitrogen application rate is more than 225 kg hm-2,the nitrogen use efficiency of each quantitative index is reduced by increase nitrogen application of wheat.When nitrogen application rate is same(240 kg hm-2),the nitrogen use efficiency of each quantitative index is increased by increase topdressing nitrogen application amount;when nitrogen fertilizer ratio of base and topdressing is 3:7,the nitrogen use efficiency in winter wheat reach the highest.The nitrogen use efficiency with Jimai22 is higher than Shannong8355.5 The effects of nitrogen management on grain yield in winter wheatWhen nitrogen fertilizer ratio of base and topdressing is same?5:5?,as the nitrogen application rate is less than 225 kg hm-2,the spike number,kernel number and 1000-grain weight is increased by increase nitrogen application of wheat;as the nitrogen application rate is more than 225 kg hm-2,the yield of wheat grains no longer increases,This shows that the nitrogen application rate exceeds the demand for nitrogen in wheat grows,which leads the nitrogen use efficiency of wheat is reduced.When nitrogen application rate is same(240 kg hm-2),the spike number and 1000-grain weight is increased by increase topdressing nitrogen application amount,the differences with kernel number between each treatment were not significant.The nitrogen fertilizer ratio of base and topdressing of 3:7 is the best treatment.Because of the difference wheat cultivars have different nitrogen use efficiency,so the grain yield with Jimai 22 is higher than Shannong8355 at the same nitrogen treatment. |
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