Effects Of Seeding Rate And Nitrogen Topdressing On Fertility Characteristics,Yield And Quality Of On Winter Wheat Xinong 805

In order to tap the yield-increasing potential of the winter wheat Xinong 805,the effects of different seeding rates and top-dressing nitrogen amounts at jointing stages on its agronomic characteristics,spikelet seed setting characteristics,yield and quality were studied,and a theoretical basis was provided for the integration and extension of the fertilizer and density supporting technologies of Xinong 805.This experiment adopted a two-factor split zone design,the seeding rate is the main area,four levels are respectively set as D1(112.5kg·hm^-2),D2(150 kg·hm^-2),D3(187.5 kg·hm^-2),D4(225 kg·hm^-2);the amount of nitrogen fertilizer applied at the jointing stage is secondary area,four levels are respectively set as N1（no urea topdressing）,N2(topdressing urea 60 kg·hm^-2),N3(topdressing urea 120kg·hm^-2),N4(topdressing urea 180 kg·hm^-2).After two years of experimental research,the main results of the study were as follows:1.The seeding rate has a significant effect on the leaf area of the flag leaf of Xinong805.With the same nitrogen topdressing rate,the flag leaf area at filling stage decreases with the increase of the seeding rate,and when the seeding rate is 112.5 kg·hm^-2,the leaf area of the flag leaf at filling stage reach the maximum.With the increase of the seeding rate,the plant height,the awn length,the flag leaf sheath length and the length of sub-spike all increase.There is a significant difference of all treatments between the high seeding rate(225 kg·hm^-2)and the low seeding rate(112.5 kg·hm^-2).Increase the amount of nitrogen topdressing can increase spikelet length.2.The number of grains at each spikelet position shows a quadratic curve that first increased and then decreased from the base to the top of the spikelet position,and reach the maximum at 7-10 spikelet positions.The fitting equations of different seeding rates and nitrogen topdressing treatments reached extremely significant levels,and the R² values are all greater than 0.781.The number of fertile spikelets,the number of florets,and the floret setting rate in different ear positions are distributed asymmetrically,and the grain development show a near-medium advantage.The number of fertile spikelets,florets and the floret setting rate at different ear positions all show the order of middle>top>bottom.Increasing the seeding rate can increase the number of fertile spikelets and the floret setting rate in different ear positions,especially in the top and bottom ear positions.The high seeding rate(225 kg·hm^-2)and the low seeding rate(112.5 kg·hm^-2)are different significantly The high-density planting is beneficial to improve spikelet seedsetting characteristics.With the increase of nitrogen topdressing,the number of grains in different ear positions,the number of top fertile spikelets,and the floret seed-setting rate of bottom all increase.The number of bottom fertile spikelets reaches the maximum when nitrogen topdressing is at the level of 180 kg·hm^-2（N4）,there are 2.07 and 1.75 respectively in2018-2019 and 2019-2020.3.Seeding rate can significantly increase the spike number and the number of groups.In2018-2019 and 2019-2020,the high seeding rate(225 kg·hm^-2)is higher than the low seeding rate(112.5 kg·hm^-2)increase significantly by 39.13%and 21.47%about the number of spike per hectare,and the thousand-grain weight decreases with the increase of seeding rate.Appropriately increasing the amount of topdressing nitrogen can increase the number of grains per spike.Increasing the amount of topdressing nitrogen can increase the number of effective spike under low seeding rate(225 kg·hm^-2),but the effect of topdressing nitrogen is not obvious under high seeding rate(225 kg·hm^-2).In 2018-2019 the yield reached the maximum value of 8438.67 kg·hm^-2 in D4N4(seeding rate was 225 kg·hm^-2,base fertilizer180 kg·hm^-2,and topdressing nitrogen amount 180 kg·hm^-2),In 2019-2020 the yield reaches the maximum value of 10136.40 kg·hm^-2 in D4N3(seeding rate is 225 kg·hm^-2,base fertilizer 180 kg·hm^-2,and topdressing nitrogen amount 120 kg·hm^-2).4.The seeding rate has a significant or extremely significant impact on the protein content,wet gluten content and sedimentation value.In the same nitrogen fertilizer treatment.the high seeding rate(225 kg·hm^-2)is reduced by 6.20%and 3.56%respectively than the low seeding rate(112.5 kg·hm^-2)about the protein content in 2018-2019 and 2019-2020.Reducing the seeding rate can optimize the processing quality of winter wheat.In different nitrogen topdressing treatments,the sedimentation value N4 is significantly increased by3.08%compared with N1 in 2019-2020.To sum up,the results of this experiment conclude that to fully tap the production potential of Xinong 805 winter wheat,field production can use 225 kg·hm^-2 seeding rate,as well as 750 kg·hm^-2 base fertilizer and 120-180 kg·hm^-2 topdressing nitrogen.